Group 3 - Homelite Fluid Pump (Gasoline Powered) - Product Dissection

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Contents

Product Dissection (Product Archaeology)

This component of Product Archaeology includes an overview of the product\'s disassembly followed by reflections upon the connections of the product\'s subsystems that are found through disassembly, and finally we conclude with comments regarding the factors influencing design.

Disassembly

This section chronicles the disassambly of the Homelite fluid pump by first providing some background information on the serviceability of engineered products, and then a detailed account of the disassembly process.

Serviceability

Before a successful dissection can be accomplished, it\'s very important to know exactly what is expected of the dissection personnel in performing each step of disassembly. This section will explore these expectations as they can be inferred by the type of connection to be dismantled and also by a difficulty scale that has been designated for the process.

Connection Types

The first way we look at the serviceability of a product is by classifying connection type. Many products are designed such that only a technical expert can repair certain parts. There can be many different reasons for designing this way (for instance, safety). Certain parts must to be removed in a very specific way or they could cause injury to the user, for example spring loaded ball bearing could cause the balls to become projectiles if taken apart incorrectly. Another reason for designing this way is to protect the user from damaging the product. Certain products if taken apart incorrectly could damage the product therefore are not intended to be taken apart, for example an iPhone.


The following table \'\'(Serviceability of Connections)\'\' defines the serviceability of connection types in terms of the ability of typical users and repair technicians separate them. Care should be taken to notice the denotations in square brackets (e.g. [U],[R],[P]) as this nomenclature will be used as shorthand in the disassembly process to remark on the serviceability of connections.

Serviceability of Connections
Connection Type Description Examples
User Serviceable

[U]

Intended for user to remove connection with basic tools or no tools at all.

  • nuts
  • bolts
  • screws


Repair Serviceable

[R]

Intended to be removed only by a technician with proper tools and equipment.

  • clearance fits
  • tamper resistant screws


Permanent

[P]

Not intended to be removed by the user nor a technical expert. These connections can not be separated without damaging the parts.

  • force fit
  • rivet
  • weld


Permanent Connections

Considering the three established connection types, one may notice that connections of the permanent type don\'t directly fit into the framework of this section, titled "Disassembly." Even though permanent connections are not to be disassembled, it is still important to remark on their presence in the product\'s design, and that is the purpose of this section. Here are a few examples of permanent connections in the Homelite fluid pump:


\'\'\'Valve Cover:\'\'\'
Picture 1: Valve Cover (Permanent Assembly)
This component consists of two thin, stamped sheet metal halves which are assembled by the crimping of tiny tabs. It\'s suspected that attempts to separate this enclosure may result in the permanent damaging of the tabs, in which case the parts could not be satisfactorily reassembled. It\'s also noted that there seem to be two more parts contained within this enclosure assembly. The yellow part appears to be plastic, and may be a some sort of baffle, while the other part may be a filter. The part serves as a port to a metal ventilation tube that connects the carburetor to the crankcase.
It is inferred because of the permanent connection either that the contained components were not considered to require replacement within the product\'s life-cycle or that if replacement is required, it would be preferable to replace the entire assembly compared to inividual parts.
\'\'\'Flywheel Magnet:\'\'\'
Picture 2: Flywheel Magnet (Permanent Assembly)
The connection between the magnet (light gray) and the flywheel (rusty brown) is identified as permanent due to the rivet fasteners observed (red arrows).
It is believed that because of the dynamic motion of the flywheel (direct rotation with the engine\'s crankshaft along with other vibrations) a permanent connection is necessary to guard against the possibility of a non-permanent fastener failing during operation. Also, the magnet is not believed to be a wear item that might require replacement, so then there is little to no need for it to be removable.
\'\'\'Coil:\'\'\'
Picture 3: Coil Assembly (Permanent Assembly)
Both the coil itself (red arrow) and the junction between te spark plug wire and the coil (green arrow) are discussed here as permanent connections. There is no observable way to disassemble either component.
The coil may quite possibly require permanent assembly because of certain tolerances, and insulative property requirements. Also, the intricacy of small gauge wire inside the coil would suggest that the skill required to repair such a part would dictate part replacement as preferential to repair should the coil fail.
The spark plug wire junction may be designed as inseparable from the coil to contain similar components in one assembly thus simplifying the design. Also, the permanent connection may increase product reliability because the wire is less likely to open circuit with the coil since it\'s glued. However, a negative aspect to this design detail is the inability to replace a spark plug wire alone should the insulation be damaged. Instead, a damaged spark plug wire may need to be replaced as an entire unit including the coil.
\'\'\'Base Foot:\'\'\'
Picture 4: Base Foot (Permanent Assembly)
The Base Foot contains three individual parts. There is the actual foot, and also two springs. The springs are assembled to the foot first by locating a loop in the spring around a stud on the base foot. Then the springs are tack welded in place.
The purpose of the welded permanent connection is evident in the functionality of the base. The springs are included in the design as a means to smooth out the vibrations of the product during typical operation. The same vibrations that caused need for the springs are the reason that permanent welds are required to hold them in place. Otherwise, a non-permanent joint could be vibrated free.
Difficulty Scale

An important scale to accurately judge difficulty is an important part in any proper dissection or assembly. The table below (\'\'Difficulty Scale\'\') is designed to give the user an accurate idea of each step\'s difficulty. The chart is divided into five different categories ranging from 1 (easily achieved) to 5 (specialist required). Any step can be placed into the appropriate difficulty based on one, or all of the following: tools required, experience and or physical effort.

Difficulty Scale
Difficulty
Requirements
Tools/Equipment Technical Experience Physical
L
E
A
S
T


















G
R
E
A
T
E
S
T
1

No tools

General household tools
(e.g. screw driver, hammer, etc.)

Requires little to no technical experience

Very minimal


2

General mechanics tools
(socket, ratchet ext.)

Minimal

Minimal


3

Multiple tools required, used together or separate

Moderate
(must exhibit the coordination to use tools simultaneously)

Moderate


4

Requires specialty tools
(e.g. mechanical pulley puller)

Technical Experience

Maximum


5

Requires specialty machinery
(e.g. hydraulic press)

Specialty Training

Machine Assistance

Disassembly Process

This section applies the previous content of this report to practical demonstration of product disassembly. It is imperative that the following sections, preparation and how-to guide be read in full, and in order, for the reader to be successful in proper disassembly.

Preparation

Proper disassembly preparation consists of thorough reading, comprehension, and execution of the following sections. Important information regarding the required tools and equipment, nomenclature, and common tasks of disassembly follows.

Tools & Equipment Required

Be sure to gather the Items listed in the following table:

Required Tools & Equipment
Item Details


Work Table
  • 3ft x 8ft area
  • Waist-Height
  • Sturdy and Stable
Bench Vise
  • 4in jaw
General Equipment
  • Spring Clamp
  • Funnel
  • Oil Pan
  • Fuel Container
General Hand Tools
  • Hammer
  • Rubber Mallet
  • Punch
  • Chisel
  • Pry Bar
Screwdrivers
  • Flat Head, 3/16 in
  • Flat Head, 3/8 in
  • Number 2 Philips
Wrenches and Pliers
  • 3/8 in Combination Wrench
  • 8 in Adjustable "Crescent" Wrench
  • Channel-Lock Pliers
  • Needle Nose Pliers (with side cutter)
Sockets

3/8 in Drive:

  • Metric (mm): 10, 11, 13, 14
  • Standard (in): 1/4, 1/2

1/2 in Drive:

  • Metric (mm): 13 (deep-well)
  • Standard (in): 3/4 (deep-well), 7/8
Sockets Drivers:
  • 3/8 in Drive Ratcheting Wrench
  • 1/2 in Drive Ratcheting Wrench
  • 1/2 in Drive Impact Gun
Specialty Tools
  • Pulley Puller
  • Valve Spring Compressor
  • Flywheel Wrench
Nomenclature

Refer to the tables above for the denotation of product serviceability in terms of connection types and difficulty. Care should be taken by the dissection personnel to be aware of personal strengths and limitations (e.g. in experience, physical strength, etc.) in completing the steps of disassembly.

Common Tasks of Disassembly
\'\'\'Threaded Fasteners:\'\'\'
A great majority of the procedures detailed in the how-to guide involve separating threaded connections. Whenever the part to be removed is referred to as a nut, bolt, or screw it may be assumed that the connection is threaded.
All threaded connections in this product are right-hand threaded. To remember how to disassemble a right-handed threaded connection, it may be helpful to refer to the mnemonic, "Righty-tighty, lefty-loosy," where right and left determine which way to rotate the fastener when looking at the head of the fastener. Right corresponds with rotating toward the right, or clockwise (CW), whereas left corresponds with rotating toward the left, or counterclockwise (CCW).
\'\'\'Using Sockets & Socket Wrenches\'\'\'
Whenever instructed to use a socket to remove a fastener, it may not be explicitly stated that a socket wrench is to be used. In these cases, it is to be assumed that for a 3/8 in drive socket, a 3/8 in drive socket wrench is required (and similarly for 1/2 in drive). It is important also to be sure that ratcheting socket wrenches are set to ratchet in the proper rotational sense to remove a fastener. Become familiar with the ratcheting socket wrench before attempting to use it in this disassembly process.
\'\'\'The Use of Required Tool & Equipment\'\'\'
It is imperative that for all tools and equipment utilized in this disassembly process, the user must be fully aware of proper usage. If the user requires information regarding proper use of any tools, he/she should consult the tools\' owner\'s manuals for proper usage procedures.
How-To Guide
The Disassembly Process
Number Description Procedure Image
1 \'\'\'Remove Base Feet\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 13 mm Socket (3/8 in drive)
  • 14 mm Wrench
For (2) Nut & Bolt connections below the Engine
  1. Locate the circular access hole (green arrow) in the bottom of the Base Foot
  2. Place the 13 mm socket (with socket wrench attached) through the access hole and seat it firmly on the bolt head
  3. Place the 14 mm wrench on the nut (red circle)
  4. Turn the socket wrench while holding the combination wrench still to loosen the connection and remove the fasteners

For (2) Bolt connections below the Pump

  1. Locate the circular access hole in the bottom of the Base Foot (green arrow)
  2. Place the 13 mm socket through the access hole and seat it firmly on the bolt head
  3. Turn the socket wrench to loosen the connection and remove the bolt
  4. Now that the fasteners are all removed, the product can be lifted off of the Base Feet
G3 diss 1a.png


2 \'\'\'Remove Pump Housing Cover\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 11 mm Socket (3/8 in drive)
  • Rubber Mallet (if required)
For (4) Bolt connections
  1. Locate the (4) bolts to be removed (two bolts picture - red circles - The other two bolts are symmetrically located on the other side of the product)
  2. Place 11 mm socket firmly on bolt head
  3. Turn the socket wrench to loosen the connection and remove the bolt

Remove the Pump Housing Cover

  1. Grasp the pump housing cover with two hands and wiggle it while pulling it away from the product
Note: \'\'If the Pump Housing Cover does not easily separate, then tap around its edges with the rubber mallet and repeat step 1\'\'
G3 diss 2a.png


3 \'\'\'Remove Pump Drain Plug\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Bench Vise (4 in or larger)
  • Adjustable Wrench


  1. Mount the Pump Housing Cover in the bench vise (green arrow)
  2. Locate the pump drain plug (red circle)
  3. Place the screw driver shank across the head on the drain plug between the two protrusions (as pictured)
  4. Using the screwdriver as a lever, turn to loosen the plug and remove it
G3 diss 3a.png


4 \'\'\'Remove the Primer Port Plug\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Bench Vise (4 in or larger)
  • Adjustable Wrench
Locate the Primer Port Plug (red circle)
  1. Mount the Pump Housing Cover in the bench vise
  2. Adjust the wrench so that it fits snugly onto primer port plug
  3. Turn the wrench to loosen and remove the primer port plug
Note: \'\'If the Pump Housing Cover moves in the vise when the wrench is turned, then it may need to be reposition in the vise, or the vise may need to be tightened\'\'
G3 diss 4a.png


5 \'\'\'Remove Pump Housing Gasket Plate\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Hammer
  • Chisel
  1. Locate the seam (green arrow) between the gasket plate (red arrow) and the product
  2. While holding the chisel firmly in one hand, place the chisel edge on the seam
  3. Tap the chisel with the hammer 3 to 5 times
  4. Move about 2 in along the seam and repeat steps 2 & 3 until the seam has separated all the way around
  5. When the seam has fully separated, grasp the gasket plate with two hands then wiggle it while pulling away from the product to remove it
G3 diss 5a.png


6 \'\'\'Drain Oil\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 8 in Crescent Wrench
  • Oil Pan


  1. Locate the oil drain plug (red circle)
  2. Position the oil pan (yellow arrow) underneath the drain plug so that it will catch all drained oil when the plug is removed
  3. Adjust the crescent wrench so that it fits snugly on the oil drain plug
  4. Place the crescent wrench on the oil drain plug
  5. Turn the wrench to loosen and remove the oil drain plug
  6. Observe the oil draining (blue circle) adjust the position of the oil drain pan if necessary to catch all oil.
Note: \'\'It may be preferred to remove the wrench from the drain plug once the plug turns freely enough to remove by hand. Removing the plug by hand will minimize the chance that it will be dropped into the oil pan (this can be very messy).\'\'
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7 \'\'\'Remove Oil Fill Plug\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Screwdriver (with suitable shank)
    • \'\'no. 2 Phillips can be used\'\'
  1. Locate the Oil Fill Plug (red circle)
  2. Place the screw driver shank across the head on the fill plug between the two protrusions (as pictured)
  3. Using the screwdriver as a lever, turn to loosen the plug and remove it
G3 diss 7a.png


8 \'\'\'Remove Air Filter Box\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 3/8 in Flat-Head Screwdriver
  1. Locate the air filter box and its mounting screw (red circle)
  2. Place the flat-head screwdriver on the mounting screw head
  3. Turn the screwdriver to loosen and remove the screw
  4. With one hand, grasp the air filter box and lift straight up to remove it
G3 diss 8a.png


9 \'\'\'Disassemble Air Filter Box Contents\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • None (only hands required)
  1. Separate the two halves of the air filter box
  2. The foam filter element and spacer parts can now be separated.

Exploded view pictured and described left-to-right: Bottom Row: air filter box bottom, foam filter element, air filter box top Top Row: spacer, air filter box mounting screw

G3 diss 9a.png


10 \'\'\'Remove Fuel Tank\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 10 mm Socket (3/8 in Drive)
  • no. 2 Phillips Screwdriver
For (1) 10 mm Bolt below fuel tank:
  1. Locate the fastener (green arrow)
  2. Place 10 mm socket firmly on the bolt head
  3. Turn the socket wrench to loosen the bolt and remove it

For (3) no. 2 Phillips screws above fuel tank

  1. Locate the three fasteners (red circles)
  2. Place the no. 2 phillips screwdriver on any one of the three screws
  3. Turn the screwdriver to loosen the screw and remove it
  4. Repeat steps 2 & 3 for a second screw
  5. Before removing the third screw we must use one hand to grasp and support the fuel tank (when the third screw is removed it could fall otherwise)
  6. While supporting the fuel tank with one hand, repeat steps 2 & 3 for the third screw
  7. Now that the fuel tank is no longer fastened to the product, lower it about 4 inches until the fuel tank clears the fuel straw (blue arrow) which was previously inserted into the fuel tank
Note: \'\'Refer to the bottom picture to see how the fuel tank (yellow arrow) must be lowered to clear the fuel straw (blue arrow) upon removal.\'\'
G3 diss 10a.png
G3 diss 10b.png
G3 diss 10c.png


11 \'\'\'Remove Fuel Fill Cap and Drain Fuel\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Approved Fuel Container
  • A Suitable Funnel (optional)
Locate the fuel fill cap (red circle) on the fuel tank
  1. Twist the fuel cap by hand to loosen and remove it
  2. Pour the fuel out of the fuel tank into a suitable storage container. In this step, the optional funnel may be placed on the storage container opening to make pouring easier.
G3 diss 11a.png


12 \'\'\'Remove Crankcase Ventilation Tube\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • None (only hands required)
The tube consists of a metal tube (blue arrow) and a rubber fitting (yellow arrow) on one end
  1. Grasp the rubber fitting with one hand and twist it back and forth while pulling gently away from the product to separate it from the carburetor
  2. Grasp the tube with one hand and twist it back and forth while pulling away from the product to separate it from the crankcase
G3 diss 12a.png


13 \'\'\'Remove Recoil Starter Housing\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 11 mm Socket (3/8 in Drive)
Locate the (3) Bolts (red circle & blue circle - one on each side)

For each of the (3) Bolts:

  1. Place the 11 mm socket firmly on the bolt head
  2. Turn the socket wrench to loosen and remove the bolt
  3. With two hands, grasp the recoil start housing and pull away from the product to remove it
G3 diss 13a.png
G3 diss 13b.png


14 \'\'\'Disassemble Recoil Starter\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Spring Clamp
  • Needle Nose Pliers
  • Pry Bar
First remove the pull handle from the rope
  1. Pull on the handle to expose at least one foot of rope, then pinch the rope with a spring clamp to prevent the roper from winding back into the recoil mechanism. (This will provide slack in the rope to make it easier to work on the handle)
  2. Hold the rubber handle (green arrow) firmly with one hand
  3. Using needle nosed pliers in your other hand, grasp the metal bar (red arrow) that is recessed in the rubber handle
  4. Pull the metal bar out of the rubber handle
  5. Untie the rope from the metal bar
  6. Pull the rope through the rubber handle (as pictured)

Now remove the recoil mechanism (yellow arrow) from its housing

  1. Locate (2) metal tabs (blue arrow - one on each side)
  2. For each of (2) metal tabs, seat the pry bar under the tab and pry up on the tab until it is vertical
  3. While holding the exposed rope firmly in one hand, remove the spring clamp (used in the previous steps)
  4. Slowly feed the rope back into the recoil housing until all of the rope is wound back into the recoil mechanism
  5. With caution, lift the recoil mechanism up just high enough to get your fingers underneath it
  6. While holding the recoil mechanism in one hand, reach the fingers of your other hand underneath the recoil mechanism to grasp the recoil spring
  7. Carefully remove the recoil mechanism and spring taking care not to allow the spring to unwind
  8. The spring can be wound tightly by rotating it clockwise and then it can be taped for storage
G3 diss 14a.png
G3 diss 14b.png


15 \'\'\'Remove Governor Plate\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Needle Nose Pliers


Locate two tabs at bottom of governor plate (red arrows - top picture)
  1. Using needle nose pliers, bend the bent tab straight
  2. With hands, slide the governor plate to the left and then pull toward you to remove it

Locate the throttle linkage connected to the top of the governor plate (red arrow - bottom picture)

  1. Hold the throttle linkage in one hand
  2. Hold the governor plate in your other hand
  3. Rotate the governor plate around the bend in the end of the throttle linkage (green arrow) to separate the connection
G3 diss 15a.png
G3 diss 15b.png


16 \'\'\'Remove Throttle Linkage\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Needle Nose Pliers
Separate the throttle return spring from the throttle adjuster arm
  1. Locate the throttle return spring (red arrow - top picture)
  2. Grasp the big loop in the end of the throttle return spring with needle nose pliers (as pictured)
  3. Pull the loop through the throttle adjuster arm (green arrow - top picture) to separate the parts

Separate throttle Linkage bar (red arrow - bottom picture) from the throttle arm (green arrow - bottom picture)

  1. Grasp the throttle linkage bar in one hand
  2. With the throttle linkage bar horizontal, lift it up until it stops
  3. While gently applying upward force, rotate the throttle linkage bar until it is vertical
  4. The throttle linkage bar should now be free, if it isn\'t then repeat steps 1-3
G3 diss 16a.png
G3 diss 16b.png


17 \'\'\'Remove Carburetor\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 3/8 in Combination Wrench
Locate (2) carburetor mounting bolts (red circle & green arrow - not visible)
  1. Place the 3/8 in combination wrench on one of the two carburetor mounting bolts
  2. Turn the wrench to loosen the bolt and remove it
  3. Grasp the carburetor assembly with one hand (it will be free when the second bolt is removed)
  4. Repeat steps 1 & 2 for the second bolt
G3 diss 17a.png


18 \'\'\'Disassemble Carburetor\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 1/2 in Socket (3/8 in Drive)
  • 3/16 in Flat Head Screwdriver
  • 1/4 in Flat Head Screwdriver
Remove Air Inlet Gasket (green arrow)
  1. Using hands, pry the rubber gasket off of the carburetor

Remove Throttle Adjuster Arm

  1. Locate the throttle adjuster arm (blue arrow)
  2. Using the 3/16 in flat head screwdriver, remove the throttle adjuster arm mounting screw
  3. Lift the throttle adjuster arm off of the carburetor to remove it

Remove Idle Adjustment Components (middle picture, exploded view shown)

  1. Use 1/4 in flat head screwdriver to loosen and remove the idle adjustment screw (and the spring beneath it) (red circle)
  2. Use 1/2 in Socket to loosen an remove the idle adjustment cap, which the idle adjustment screw was threaded into (red circle)
  3. Use dental pick to remove o-ring
  4. Use 3/16 in flat head screwdriver to loosen and remove idle valve jet

Remove Throttle Arm Minimum Throttle Adjusting Screw (white arrow)

  1. Use 3/16 in flat head screwdriver to loosen an remove the adjusting screw

Remove Cover Plate (red arrow) and Contained Components

  1. Use 3/16 in flat head screwdriver to remove (4) screws (orange circles)
  2. The fasteners are removed, but the cover is still held on by a locating pin
  3. Rotate the cover back and forth about the locating pin while pulling it away from the carburetor to remove it
  4. Remove the contained metal ring and spring by hand



G3 diss 18a.png
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G3 diss 18c.png
G3 diss 18d.png
G3 diss 18e.png



19 \'\'\'Remove Spark Plug\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 3/4 in Deep-Well Socket (1/2 in Drive)
Remove Spark Plug Wire (green arrow)
  1. Using your hand, rotate the end of the spark plug wire back and forth while pulling it away from the spark plug.

Remove spark plug (red arrow)

  1. Place the 3/4 in deep-well socket on the spark plug firmly
  2. Turn the socket wrench to loosen and remove the spark plug
G3 diss 19a.png
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20 \'\'\'Remove the Exhaust Manifold (Muffler)\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • Channel-Lock Pliers
Locate the Exhaust Manifold (green arrow)
  1. Adjust the channel-lock pliers to fit onto the narrow part of the exhaust manifold near the engine (silver pointer)
  2. Place the pliers on the exhaust manifold and grip firmly
  3. Turn the pliers to loosen and remove the exhaust manifold from the head of the engine


G3 diss 20a.png


21 \'\'\'Remove the Carry Handle\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 3/8 in Combination Wrench
For each of (2) mounting bolts:
  1. Place 3/8 in combination wrench on the bolt head (red circles)
  2. Turn the wrench to loosen and remove the bolt
  3. The handle (green arrow) is free to be removed after the bolts are removed
G3 diss 21a.png



22 \'\'\'Remove Engine Head\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 13 mm Socket


For each of (8) Head Bolts (red circles):
  1. Place 13 mm socket on the head of the bolt
  2. Turn the socket wrench to loosen and remove the bolt
  3. Remove head shroud (thin piece of metal on top of the head
  4. The head and head gasket (below the head) now free to be removed by hand
G3 diss 22a.png



23 \'\'\'Remove Pump Impeller\'\'\'

\'\'\'Difficulty:\'\'\' 4

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 7/8 in Socket (1/2 in Drive)
  • Impact Gun
  1. Place 7/8 in socket on the hexagon head of the impeller (green arrow)
  2. Use impact gun to remove impeller from the engine crankshaft
G3 diss 23a.png



24 \'\'\'Remove Pump Housing\'\'\'

\'\'\'Difficulty:\'\'\' 4

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 13 mm Socket (1/2 in Drive)
  • Impact Gun
  • Pry Bar

For each of (4) mounting bolts (red circles)

  1. Place 13 mm socket firmly on bolt head
  2. Use impact gun to remove the bolt
  3. Use pry bar to slide the steel collar and spring (green arrow) off of the crankshaft
  4. Firmly grasp the pump housing with two hands
  5. Rotate the housing back and forth while pulling away from the engine to remove it
G3 diss 24a.png



25 \'\'\'Remove Front Shroud\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 1/4 in Socket (3/8 in Drive)


Locate Front shroud
  1. Use 1/4 in socket to remove one cap screw (green circle)
  2. Remove the front shroud by hand


G3 diss 25a.png


26 \'\'\'Remove Governor Mounting Plate and Coil\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 1/4 in Socket (3/8 in Drive)
  • Wire Cutters (Optional - Not Typical)


Locate two mounting screws (yellow and red circles)

To remove the governor mounting plate (green arrow)

  1. Use 1/4 in socket to remove the left screw (yellow circle)
  2. Lift the governor mounting plate up and to the left so that the hole clears the pin (red arrow)

To remove the coil (white arrow)

  1. Use 1/4 in socket to remove the other screw (red circle)
  2. The coil now lifts off by hand, but is still connected to the engine by a wire that cannot be disconnected
  3. (Optional) Cut the wire with wire cutters in order to separate the component from the assembly
G3 diss 26a.png



27 \'\'\'Remove Mesh Flywheel Shroud\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 1/4 in Socket (3/8 in Drive)


Locate Mesh Flywheel Shroud
  1. Use 1/4 in socket to remove (2) cap screws (red circles)
  2. Remove the mesh flywheel shroud by hand
G3 diss 27a.png



28 \'\'\'Remove Side Flywheel Shroud\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 11 mm Socket (3/8 in Drive)
Locate the mounting bolt (red circle)
  1. Use 11 mm socket to remove the mounting bolt
  2. Remove the side flywheel shroud (green arrow) by hand
G3 diss 28a.png



29 \'\'\'Remove Crankcase Cover\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 11 mm Socket (3/8 in Drive)
  • Pry Bar
  • Rubber Mallet (if required)
  1. Use Pry Bar to remove rubber gasket (green arrow)
  2. Use 11 mm socket to remove (6) crankcase mounting bolts (red circles show bolt locations - bolts not pictured)
  3. Use two hands to grasp the crankcase cover (blue arrow) and rotate it back and forth while pulling away from product to remove
Note: \'\'The rubber mallet may be used to tap around the edges of the crankcase cover if it is stuck in place during step 3\'\'
G3 diss 29a.png


30 \'\'\'Remove the Engine to Base Bracket\'\'\'

\'\'\'Difficulty:\'\'\' 2

\'\'\'Connection Type:\'\'\' [U]

\'\'\'Tools Required:\'\'\'

  • 1/2 in Socket (3/8 in Drive)
  1. Use 1/2 in socket to remove (2) nuts (red circles)
  2. Remove the bracket (green arrow) by hand
G3 diss 30a.png



31 \'\'\'Remove Crankshaft Support Bearing\'\'\'

\'\'\'Difficulty:\'\'\' 4

\'\'\'Connection Type:\'\'\' [R]

\'\'\'Tools Required:\'\'\'

  • Suitable Pulley Puller


  1. Mount the puller (read arrow) on the bearing crankshaft assembly as per the tools instructions for use
\'\'This typically involves retracting the tool\'s threaded ram enough to seat the end of the threaded rod on the end of the shaft and close the jaws around the object to be pulled off of the shaft\'\'
  1. With the puller mounted, tighten the implement to pull the bearing (green arrow) off of the crankshaft (yellow arrow)
G3 diss 31a.png



32 \'\'\'Remove Camshaft\'\'\'

\'\'\'Difficulty:\'\'\' 1

\'\'\'Connection Type:\'\'\' [R]

\'\'\'Tools Required:\'\'\'

  • None - Only Hands


Locate the Camshaft (green arrow)
  1. With one hand, grasp the gear end of the camshaft
  2. Rotate the camshaft as you pull it toward yourself out of the assembly
Note: \'\'The camshaft must be rotated in order to manipulate its eccentric lobes (arrows - b) past internal components. This can be somewhat tricky, but patience will prevail.\'\'
  1. Now the lifters (arrows in the lower picture) can be removed by hand. They are located inside the engine cavity just above where the camshaft was located.
G3 diss 32a.png
G3 diss 32b.png



33 \'\'\'Disconnect Connecting Rod from Crankshaft & Removing Piston/Connecting Rod\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [R]

\'\'\'Tools Required:\'\'\'

  • Suitable Flat Head Screwdriver (3/8 in can be used)
  • 10 mm Socket (3/8 in Drive)
Locate (2) bolts (red arrows)
  1. There are tabs surrounding the bolt head that must be bent down using the flat head screwdriver
  2. Using the 10 mm socket, remove (2) bolts
  3. Remove the free parts (red circle)
  4. Using your hand, push the connecting rod (green arrow) up, forcing the piston (blue arrow) out the top of the engine
  5. When the piston is exposed, grasp the piston and pull it out all the way
G3 diss 33a.png
G3 diss 33b.png



34 \'\'\'Disassemble Piston/Connecting Rod Assembly\'\'\'

\'\'\'Difficulty:\'\'\' 3

\'\'\'Connection Type:\'\'\' [R]

\'\'\'Tools Required:\'\'\'

  • Needle Nose Pliers
  • Small Hammer
  • Punch


Locate (2) Wrist Pin retaining clips (green arrow - one pictured, one symmetrically located on the other side of the piston [blue arrow])
  1. Using needle nose pliers, grasp the spring clip and pry it free (for each clip)
  2. Using a hammer and punch, set the punch through the hole in the piston, resting on the end of the wrist pin (red arrow)
  3. Gently tap the punch to force the wrist pin out of the piston
  4. Once the wrist pin is free, the piston, wrist pin, and connecting rod can be separated by hand
G3 diss 34a.png



35 \'\'\'Remove Valves\'\'\'

\'\'\'Difficulty:\'\'\' 4

\'\'\'Connection Type:\'\'\' [R]

\'\'\'Tools Required:\'\'\'

  • Valve Spring Compressor
  • Needle Nose Pliers
For each of (2) assemblies:
  • Use the valve spring compressor tool according to it\'s instructions for use to compress the valve spring (green arrow)
Note: \'\'This will move the bottom edge of the spring up toward the top edge of the spring\'\'
  1. Use needle nose pliers to grasp the spring retainer clip (blue arrow)
  2. Manipulate the spring retainer clip so that it passes over the bottom end of the valve stem (red arrow)
G3 diss 35a.png



36 \'\'\'Remove Flywheel\'\'\'

\'\'\'Difficulty:\'\'\' 4

\'\'\'Connection Type:\'\'\' [R]

\'\'\'Tools Required:\'\'\'

  • Hammer
  • Punch
  • Flywheel Wrench
  • Wooden or Plastic Shaft (non-marring)

(a wooden hammer handle can also be used to keep the shaft from spinning)

Remove the aluminum nut (red circle)
  1. Apply the flywheel wrench to keep the flywheel (red arrow) from turning
Without access to the flywheel wrench, a wooden hammer handle (blue arrow) can be inserted through the engine cylinder to keep the flywheel and crankshaft from rotating as pictured
  1. Place the punch (white arrow) on one of the tabs on the aluminum nut.
  2. Hit the punch with the hammer to loosen the nut, then remove it.

Remove the flywheel (red arrow)

  1. Position the assembly as shown in the third picture with the end of the crankshaft (orange arrow) resting on a stable surface (workbench)
  2. Using the hammer, hit the backside of the flywheel (black arrow) until it drops to the table, free from the crankshaft.
  3. Separate the parts by hand recovering the following (listed in the order pictured, left-to-right and top-to-bottom):
  • Crankshaft
  • Key (orange circle)
  • Crankcase
  • Flywheel
  • Nut
G3 diss 36a.png
G3 diss 36b.png
G3 diss 36c.png
G3 diss 36d.png

Challenges Faced With Disassembly

Through the disassembly process group 3 encountered just a handful of small challenges, and more notably, one substantial challenge pertaining to the completion of the final step of disassembly.

Small Challenges

Two cases of small challenges faced include the following:

  • \'\'\'Partially seized (due to corrosion) fasteners\'\'\'
    • Penetrating oil used to facilitate removal of fastener
  • \'\'\'Positioning Components with Stability to Perform Disassembly\'\'\'
    • Alex and Mark (Technical Team) had to work together with simultaneous coordination to perform some disassembly tasks.
Substantial Challenge

Upon the final step of disassembly, group 3 encountered the first and only major challenge with dissection. Contrary to the proper disassembly method depicted in \'\'Step 36\'\' of the how-to guide, the initial approach to removing the flywheel was problematic.

Challenge
Pictures
Initial Method of Flywheel Removal
Damage to Pulley Puller Tool
Damage to Crankshaft

The group\'s technical assistant, Mark, decided upon inspection of the connection to assume that both the nut and the flywheel were pressed onto the crankshaft. Based upon this assumption, a Pulley Puller was implemented to pull both of the components off of the crankshaft. This configuration is shown in the picture \'\'Initial Method of Flywheel Removal\'\'.

You will recall that the nut is threaded onto the crankshaft, such that this method could only possibly succeed in separating the nut and flywheel from the crankshaft if every thread between the nut and crankshaft fails. Fortunately, in our experience the threads did not fail (which would result in critical damages to the affected parts). However, damages were indeed incurred as a result of the faulty method.

There are two reasons that the threads did not fail. Both the tool used and the crankshaft itself were damaged to the point of halting the faulty removal method before the threads could be damaged. The picture \'\'Damage to Pulley Puller Tool\'\' shows the damage to the pulley puller tool which suffered a fracture failure due to excessive forcing. The damage incurred to the crankshaft is depicted in the picture \'\'Damage to Crankshaft\'\'. The crankshaft suffered damage in the way of flaring at the end of the shaft (from the point on the pulley puller tool) and also a slight bend in the crankshaft\'s axis. It\'s apparent that the crankshaft was not designed to withstand the forces applied using this removal method, so possible conclusions might be:

  • The part is not intended to be removed
  • The method being used is incorrect

It was the opinion of group 3 that these parts should indeed be separable, and so we turned to our instructors for assistance.

Resolution

Immediately upon discovering the problems with disassembling these components, group 3 decided that the best course of action to take toward resolution demanded communication with instructors Phil Cormier and Andrew Olewnik. In order to effectively communicate the problem, Mark Tomaszewski (\'\'Communication Liaison\'\'), drafted a G3_dissectionIssueRequestForAssistance.pdf

including a brief and concise description of the problem, an annotated photo for visual reference, and a specific request for assistance.  The document was then attached to an e-mail which was promptly sent to both instructors.

In timely fashion, e-mail response was received from both instructors. Mark communicated further with Phil Cormier toward orchestrating a hands-on assessment of product disassembly in person. Mark soon met with instructor Cormier in his office (off office hours) from where Phil generously provided Mark with individual attention by escorting him to the Engineering Machine Shop, and subsequently taking the lead in assisting with product disassembly.

Through the assistance of instructor Cormier and personnel in the machine shop, it was learned that the nut actually is a nut. A punch and dead-blow hammer were acquired along with a steel scrap (to keep the crankshaft from rotating) and the disassembly procedure for \'\'Step 36\'\' of the how-to guide was performed for the first time. In less than five minutes the proper procedure was successful in disassembling the components.

In reflection, instructor Phil Cormier can be quoted, "Hindsight is 20/20." It surely is true that learning the hard way provides those who struggle with a clearer view of proper procedure upon resolving faulty methods. But group 3 realizes that a valuable extension to Phil\'s quotation would speak toward the value of the foresight that can be accomplished through research. If group 3 had performed adequate research of the product (possibly including the acquisition of a service manual for the product\'s engine), then that sort of foresight may have allowed the group to avert this challenge before it could have been encountered.

Connection of Subsystems

The connection of subsystems in the Homelite fluid pump involves analysis of its energy, signal, and mass flows as well as consideration of the global, societal, economic, and environmental (GSEE) factors that may have been considered with the product\'s engineering development. Many of these aspects have been previously considered by Group 3. Chronologically, the G3_ProductProposal.pdf

was the first time that both functional flows of the product\'s subsystems and influence of the GSEE factors were explored.  Further insight has been gained in these topics with the revisiting of energy flows in Gate 1 with the  

Initial Assessment - Energy Profile. This history has led the group to unfold successive interpretations of the product\'s energy and mass flows as well as the influence of the GSEE factors in its design.


Energy Flows

The product as a whole undergoes a specific series of energy flows so that the product can function properly. Refer to the \'\'Energy Flow\'\' Flow Chart in the following paragraphs.

Energy Flow (Flow Chart)
\'\'\'Fuel Tank & Carburetor\'\'\'
The predominant energy source for the fluid pump is in the form of stored chemical potential energy (CPE) in the fuel. The fuel travels through the carburetor on its way to the combustion chamber, along which path CPE isn\'t modified.
\'\'\'Combustion Chamber\'\'\'
The combustion chamber consists of a couple basic components which define its volume, the cylinder and the piston. In order to describe the energy flow through the combustion chamber, the contained process of combustion will be considered chronologically. The combustion chamber receives CPE input in the form of fuel from the carburetor which occupies the volume contained by the cylinder. Next, an additional input of electrical energy (EE) from the \'\'Spark\'\' Plug is introduced to the cylinder volume. The combination of CPE and EE begins the combustion process which transforms the combined energies into translational kinetic energy (TKE) of the combustion chamber\'s piston component (Note: the Combustion process is considered here on a higher level, the intermediate energy conversion through thermal energy is omitted as is the resultant waste heat). And thus, TKE is the form of the combustion chamber\'s energy output.
\'\'\'Crankshaft\'\'\'
The TKE of the combustion chamber\'s piston is then passed on to the crankshaft. The physical connection between the piston and the crankshaft can be described in terms of the actual physical connection (via the connecting rod component and a couple of bearing interfaces), and also more importantly, the geometric (or kinematic) nature of the connection. The physical geometry of the connection between the translating piston and the rotating crankshaft is characterized by axial eccentricity in the crankshaft\'s shape. This is critical to the crankshaft\'s function in transforming TKE into rotational kinetic energy (RKE).
\'\'\'Pump\'\'\'
The final node in the energy flow for the product involves the pump subsystem. The pump receives a RKE input from the crankshaft via a rigid physical connection. The pump uses the RKE energy input to perform work. Theoretically, the work performed by the pump in pumping fluid is considered to be internal to the pump system block, and so no energy output is shown.

Mass Flows

Two mass flows have been identified in this product. They are the air/fuel and the fluid mass flows. The following picture diagrams should be used as reference in the next two sections.

Mass Flows
Air/Fuel Mass Flow (Diagram)
Fluid Mass Flow (Diagram)


Air/Fuel Mass Flow
Air/Fuel Mass Flow (Flow Chart)
\'\'\'Fuel Tank & Air Filter Box\'\'\'
The air/fuel mass flow begins at the fuel tank, and at the air filter box where the two masses exist separately. The fuel is stored in the fuel tank, which imposes physical requirements on the tank to contain some adequate volume of fuel, and also be accessible for the purposes of refueling by the user. At this step, the air is continuously flowing into the air box, which demands that the air box be open to atmosphere (the source of air).
\'\'\'Carburetor\'\'\'
Simultaneously, both the air and the fuel travel from their respective initial locations to a similar component, the carburetor. It might be suggested that the air filter box and fuel tank both are placed within relative proximity of the carburetor, but this doesn’t seem to be a constraint that is necessary for the product’s functionality. Within the carburetor, air and fuel are mixed through a process called atomization, so from here the mass will be referred to as an air/fuel mixture.
\'\'\'Combustion Chamber\'\'\'
From the carburetor, the air/fuel mixture flows into the combustion chamber, and it is critical to the engine’s functionality that the air/fuel mixture still be atomized. With this in mind, it follows that a physical design constraint is that the carburetor must be directly connected to the combustion chamber such as to prevent the condensation of the atomized air/fuel mixture. From the combustion chamber, the last step of this mass flow involves the exiting of waste exhaust gases which are the byproducts of the air/fuel mixture’s combustion. It may be desirable for the design of the product for the exhaust outlet to be free from obstruction such that the exhaust can exit the product without impediment.
Fluid Mass Flow
Fluid Mass Flow (Flow Chart)
\'\'\'Pump\'\'\'
The pump system performs a simple function in terms of mass flow. However simple, this functionality should be regarded with importance as it is the main functional purpose of the product. The pump operates with fluid as its input and also as its output. The process is pretty straight-forward at a high level in the sense that the pump\'s main function is to draw in the fluid to be pumped from some source, for instance a flooded ditch, and transport is to another more desirable location. But more specifically, the ways in which the pump performs this function are a bit mysterious. The physics involved with creating the necessary negative pressure at the pump\'s inlet (such as the suck fluid) and positive pressure at the pump\'s outlet (such as to eject fluid) constitute the physical nature of the system\'s design. Without specific understanding of the physics mentioned it is quite unreasonable to speculate much further with respect to the ways in which the pump\'s physical connections influence mass flow functionality.

Factors Influencing Design

Some of the factors that may influence a design in general include those that are the four GSEE factors. Of these four factors, global, societal, and economic are focused upon in this section.

Global

\'\'Global factors are influences on the design that result from cultural and geographic features specific to a region or originating from the interaction of two or more culturally/geographically distinct regions.\'\'

\'\'\'Choice of Fuel Source\'\'\'
This product has been found to have been developed in its time period for use in the Northern American geographic location. As such, the fuel choice was obvious. Gasoline is used in gross majority compared to other fuels (even the number one runner-up, diesel) in small machinery such as this fluid pump. Though fuel choice may also be influenced by the societal impact on consumers because of the availability of the fuel required, it\'s proposed that fuel choice is firstly, and mostly, a global factor. The reasoning applied to make this determination is based upon the rationale that is the prodcut were developed in other areas of the world, it may have been designed to run on petrol in areas of Europe, and maybe even lesser quality fuels for under-developed nations.

Societal

\'\'Societal factors are influences that result from considering the impact (e.g., safety, lifestyle, etc.) on the people and society within which a product is being used.\'\'

\'\'\'Tool Requirements for Routine Maintenance\'\'\'
In particular, one routine maintenance procedure involves cleaning the air filter. And the design influences regarding this task relate specifically to the impact on those individuals who use the product. The procedure for cleaning the air filter requires performing \'\'Step 8\'\' & \'\'Step 9\'\' of the how-to guide from which it can be noted that this procedure requires a flat head screwdriver. A label on the product recommends cleaning the air filter periodically through typical usage conditions such that it must be cleaned at least once with every use. Other products with similar frequency of routine maintenance tasks may be designed with tool-less disassembly to facilitate performing such tasks. But the Homelite fluid pump is not. This may be indicative of the designers\' intention for the air filter box to be more ruggedly connected with the effect that it can be more reliable for demanding operational circumstances. But also, the designers may have suspected the users of this product to be more mechanically inclined than typical consumers in that they own general hand tools. This design, which incorporates an off-the-shelf fastener was probably less time-intensive to conceive and thus the preferable choice for designers in the absence of the demand for tool-less assembly.

Economic

\'\'Economic factors are influences that result from the economic conditions at the time of a product’s development and its past, present, projected sales and support life cycle.\'\'

\'\'\'Material Choice: Steel\'\'\'
The gross majority of power-transmission components internal to this product\'s engine and pump subsystems are manufactured from steel. Although it can be argued that steel is chosen because of its resilience to high pressure and high temperatures among other material properties, that is not the last line of reasoning in selecting steel as a core material for this product. The bottom line is that steel is the most ideal choice of material that satisfies the material requirements for functionality while also being \'\'affordable\'\' to manufacture, and thus \'\'affordable\'\' for consumers to purchase.