Lawnmower question

How do I get the flywheel off my 4-stroke Lawnboy mower; model 10360? I need to replace the ground wire, and I can’t reach the plug under the flywheel. My FIL suggested getting a 3-prong tool with a center stud to pull it off, like a gear puller. Any suggestions? The grass is growing, and the Mrs likes a neatly trimmed lawn.

He’s right. You could try using a torch to heat it up, then smacking it with a rubber mallet. Put a little penetrating oil on the crankshaft end while you debate your next move. Or, you can try my system, which involves beer, swearing a lot and eventually damaging the engine.

There Must Be Some small Threaded Holes In The Flywheel Top That Will Accept The Screws On A Harmonic Balancer Puller.

Get a puller (many come with different screws and will adjust). If it doesn’t come with the right thread on the screws then get some at a hardware store. The screws should turn into the flywheel by hand. Turn them in evenly, but don’t tighten them too much. Then tighten the center bolt on the puller and when it’s pretty tight smack the end of the center bolt with a mallet or dead-blow hammer. It’ll sound like a train wreck and pop right off.

Oops. I should have mentioned to loosen the flywheel center nut several turns before doing the above. Sometimes the threaded holes are hiding under a little tin cover.


When I worked for two years fixing lawn mowers and snow blowers (37 years ago), I removed many flywheels - and never once had to use a pulley, or ever saw one used.
The methods risk damaging the motor, so if your not comfortable, get a pulley.

I recall using two methods.

1: Insert a big long screwdriver under the flywheel and apply steady lifting pressure to it with one hand. In the other hand, tap the flywheel on the side.

2: Screw on the crankshaft nut so that the shaft end and nut are flush with each other. In one hand, use the long screwdriver (as above) and apply lifting pressure. In the other hand, use a hammer to hit the crankshaft-and-nut squarely. Hit it softly because you don’t want to damage the threads (though you need to hit it hard to damage the threads).

You will find the above procedure in no book, but it was commonly used back then, and probably still is today in small motor repair shops. Someone please let me know if it isn’t.

Yes, you should use a flywheel puller, but I’ve been working on small engines since I was 12, which is about 50 years and never used one yet. If you would like, put the nut back on the spindle so you don’t wreck the threads, put a little pry bar or screw driver under the flywheel and put some pressure on it and give the spindle a whack or two with a hammer. Some are harder than others but usually a wrap or two is all it takes to pop it loose.

If you pry, align the screwdriver with the flywheel key so that there is less chance of breaking the flywheel. I broke one on a Tecumseh once. Never broke a Briggs & Stratton. I recommend the puller, but if you don’t use it right, same thing happens.

I used the following technique to remove the flywheel: Remove the nut that holds the flywheel to the shaft. Screw the nut back on so that the shaft is well below the top of the nut. Have someone tap on the nut with a hammer while you pull up on the flywheel. This has worked for me and I have never damaged the flywheel or the key.
Incidentally, this was the suggested technique recommended in the owner’s manual of the LawnBoy mower that my Dad purchased in 1955. The engine was a 2 stroke, but I have used this same method on 4 stroke engines. The owner’s manual for this lawnmower was great. It showed how to completely disassemble and reassemble the engine. I was in high school and did a lot of mowing. At the end of the season I would replace the magneto points, needle and seat valve in the carburetor and, in addition, every other year replace the piston rings.

They sell brass and lead hammers for work like this…

Thanks for the responses. I got a harmonic balancer puller and it worked fine. I needed to get 3x 1/4"-20 bolts that are 4" long; the puller didn’t have bolts that small. I also had to tap the 3 holes to accept the 3 bolts. But I have a tap set and that was quick. Unfortunately, when I hooked up the new ground wire, the mower wouldn’t start. I removed the wire under the flywheel before I pulled the flywheel, and it’s not easy to spot the plug. I suppose all I have to do is ground it to the engine block. It’s a
Tecumseh 5 HP engine, LEV-120. I’ll search the internet, too.

Good luck on getting your mower running. I understand that Tecumseh went out of business last year.

IIRC that ground wire goes over to the speed lever and is grounded when the lever is moved to the ‘off’ position. Therefore, the engine will probably not run if the wire is permanently grounded.

I read a bit more on line, and I agree with you. The lawn mower shop didn’t have a ground wire in stock, so I made one. I plugged it into the back end of the stop wire assembly, and I think that is where it belongs. I’m going to look more closely at it next week. I had a more important job today: I replaced the rear pads and rotors on my Accord. And I found my new, favorite too! I’ll tell you about it in a new thread.

I mentioned my favorite tools in your new thread. These are the tools I would use on any lawnmower.