Gate 4 for Group 4

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Reassembly Steps

We have included a step by step chart to reassemble our lawn mower motor. We have outlined each step according to what our reassembly procedure was. Included in this list is a set of tools that was necessary to have available in order to reassemble the motor properly.

Easy = Direct access to components, using hands or tools to insert screws/bolts.

Medium = Less direct access to components, using tools only to insert screws/bolts.

Hard = Indirect/difficult access to components using tools, and sometimes application of force in order to indirectly insert screws, bolts, and components.

Step Description Tool Easy Medium Hard!
1 Insert piston into engine block (Figure 7). Hands X
2 Insert oil filter (top and bottom components) (Figure 11 and 12). Hands X
3 Rescrew top cap into engine block, re screwing two 5/16” bolts. Nutdriver X
4 Insert three piston rings (Figure 7). Small screwdriver and piston ring remover. X
5 Insert two piston clips (Figure 7). Pliers X
6 Put in cam shaft (Figure 10). Hands X
7 Put in crank shaft (Figure 9). Hands X
8 Insert flywheel (Figure 8), applying much force. Hands X
9 Insert piston valve with spring from engine block, applying moderate force. Hands X
10 Insert piston arm into piston (Figure 7), re- screwing two ¼” bolts. Nutdriver X
11 Insert valve lifters into engine block. Hands X
12 Put together top black engine cover, re screwing six 3/8” bolts. Nut driver X
13 Insert engine gasket. Hands X
14 Insert engine head (Figure 3), re screwing eight ½” bolts. Nut driver X
15 Insert spark plug into head. Hands X
16 Re screw valve gasket, screwing two 5/16” bolts. Nut driver X
17 Insert carburetor (Figure 5 and 6) into intake tube with gasket, screwing in two bolts. Nut driver X
18 Hook gas line to carburetor (Figure 5). Pliers X
19 Insert muffler (Figure 4), screwing two 7/16” bolts. Nut driver X
20 Insert coil into top, screwing in two 5/16” bolts. Nut driver X
21 Insert gold cap into top of flywheel (Figure 3), screwing in a ¾” bolt. Nut driver X
22 Put on fan cover (Figure 2), screwing in two 3/8” bolts. Nut driver X
23 Insert oil dipstick. Hands X
24 Insert plastic gas tank (Figure 1). Nut driver X
25 Insert air filter lid, screwing in one Phillips-head screw. Screwdriver X
26 Insert air filter, screwing in two ¼” bolts. Nut driver X
27 Insert pull chord, screwing in two ¼” bolts. Nut driver X
28 Hook carburetor lines. Pliers X
29 Insert pulley bracket onto bottom of crankshaft. mallet X


DSC00177.JPG DSC00183.JPG
Figure 1 – Plastic gas tank. Figure 2 – Fan cover.
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Figure 3 – Gold cap and engine head. Figure 4 – Muffler(exhaust)
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Figure 5 – Carburetor with gas line. Figure 6 – Carburetor.
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Figure 7 – Piston and piston arm.F Figure 8 – Flywheel.
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Figure 9 – Crank shaft. Figure 10 – Cam shaft.
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Figure 11 – Oil Filter on top of engine block. Figure 12 – Oil filter.
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Figure 13 – Bottom of Engine block with cam shaft. Figure 14 – Broken gear.

Other Points

 Does the product still run?

Our product still runs, even though we took it apart. We were able to restore the engine to its original condition. We were happy with this result because it shows that we were able to dissect and put the product back together correctly.

 What was different than the dis-assembly?

We were able to completely reassemble the product without much trouble, except for the valve springs, which were very difficult to put back on. It was difficult because of the small space we had to get into, where the springs and valves were supposed to go. When we reassembled the product, we used all the same screwdrivers and socket sets. One tool we didn’t use was the puller that we used to pull the belt pulley bracket off of the crankshaft. We had to put the bracket back on, so we used a mallet to tap the bracket back on. The piston was much harder to put back into the cylinder than to take out. We were able to just pull it out when we disassembled the engine, but when we put it back together, the piston rings kept getting in the way. So we had to push the rings in so we could push the cylinder in, and that was hard because we had to press all around the ring. Other than most of the steps being in the reverse order, there weren’t any more notable differences between the disassembly and the reassembly.


We recommend that the oil filter be moved to a different position, because the place it is in now is underneath the flywheel. This makes it difficult to get to if you are just replacing the filter. Given the choice, we believe that most people would rather replace an oil filter than buy a whole new lawnmower. However, with the inconvenient position of the oil filter, many people will probably not think about it or bother with changing it. This may have been done purposely by the manufacturer in order to sell more lawnmowers, but we suggest this in order to improve product efficiency and quality.

Main Page

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Group 4 - Lawn Mower Engine