| Lawnmower Engine Repair -- Engine Removal |
From "Weekend Mechanic"
episode WKM-104 |
|
|
|
advertisement
|
In this episode, Weekend Mechanic Bruce Bonebrake shows how to repair a lawnmower engine that' s seen better days. The problem: The engine in our riding mower has logged more than 1100 hours of duty, and has basically worn out. The engine has begun to emit some smoke, and starting has become difficult. However, after initial inspection, it's determined that the engine is not fully beyond repair. DIY Difficulty-Rating for Repair: A complete overhaul and rebuild on a riding-mower engine is a two-day job. However, it is a fairly easy and straightforward project compared to larger engine repairs. In fact this is recommended as a good project for the family, and can help budding weekend-mechanics learn some engine basics. An experienced mechanic could complete the project in a single day, but we took our time, completing the repair in two days. We give this project a difficulty rating of 1 on a 5-point intermediate-level scale. Important: Included below are the steps in this mechanical repair procedure as shown in the episode. These steps are general guidelines that are applicable to most riding mowers. With any particular model, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that model. Always consult your owner's manual or service manual when undertaking significant mechanical repairs. In addition to standard mechanic's tools, some of the specialty tools that will be needed for this project include a dial caliper (figure A), telescopic gauge (figure B), strap wrench, piston-ring compressor, ring expander, pounds-per-inch torque wrench, feeler gauge, valve-lapping tool, flywheel puller, telescopic gauge, and valve-spring tool. There are three basic choices for this engine repair, depending on the severity of the problem: - Replace the entire engine assembly (figure C), at a cost of $550 to $750.
- Replace the short block (figure D) -- the portion of the engine with the essential moving parts -- at a cost of about $350.
- Rebuild the existing engine, using a variety of replacement parts (figure E). The rebuild option should cost in the neighborhood of $100 for parts.
We opted for the third, least expensive option since this single-piston engine is still in reasonably good shape. Engine Removal - Before beginning the engine repair, disconnect the battery cables (figure F), including the ground cable where it attaches to the metal body.
- Detach the wiring harness and throttle cable, and clamp and disconnect the fuel-supply hose (figure G). Be sure to clamp the hose before disconnecting, to avoid a gasoline spill. Note that the wires and hoses on old mowers may be worn, so use caution when detaching them. Some may need to be replaced. The ones on the mower in our demonstration were in good shape, so they were retained for re-use.
- Unbolt and remove the hood and grill assembly (figure H) for better access to the engine.
- With help from an assistant, raise and set the front axle of the mower on jack stands (figure I).
- Remove the bolts that hold the engine on the mower, unbolting the engine mounts from below (figure J).
- With the engine lines disconnected and engine unbolted, and with the help of an assistant, carefully lift the engine off of the mower (figure K).
- Important: Be sure that, before removing the engine, you have a secure place to rest it while you work on it. This means you'll need to have a way of setting the engine down on a surface that allows the crankshaft to extend down below the surface, without damaging the crankshaft. To do this, we modified a heavy-duty plastic crate -- cutting a hole in the upturned bottom into which the crankshaft to extend (figure L).
In the segment that follows, the engine is disassembled and checked to see exactly what repairs are necessary.
RESOURCES :
The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books
Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896
The Haynes Small Engine Repair Manual
ISBN: 1850106665
Author: Curt Choate, John H. Haynes
Haynes Publishing Group
Chilton's Small Engine Repair Up to 20 Hp
Model: 0801983258
Author: Kerry A. Freeman
Nichols Publishing
Small Gas Engine Repair
Model: 0830641424
Author: Paul "How to Troubleshoot" Dempsey
| 
)
)
)
)
)
)
)
)
)
)
)
)
