Flywheel removal 40 HP Evinrude

[outbdnut2]

Hi, I finally found a flywheel I can’t get to come off. 1961 40 HP Evinrude Lark. I’ve had a bolt puller on it for a week. Have put liquid wrench on it, and the last couple days I tried transmission fluid. I have hit the center bolt on the puller with a hammer a couple times every day, and have tightened it a bit each day. I don’t know if I dare tighten the puller any tighter – afraid puller bolts might rip out – or does this never happen? Any tips on how to break this loose would be great! The last couple times I tightened the canter bolt, I had to put a long crescent wrench on it and hit the handle with a hammer to make it move. I don’t like to use heat on these things, but I could heat around the center with a propane torch if that is acceptable?? Ideas??
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Help!
Thanks!
Dave

[garry-in-michigan]

When Flywheel problems showed up on the 1960 Evinrude Bigtwin/Lark 40 horse, they changed the crankshaft and flywheel. The crankshaft and flywheel is heaver and the flywheel key is smaller. The key is only there to locate the flywheel so it is synchronized with the breaker points. The flywheel has a slightly different taper than the crankshaft and when the Flywheel is properly torqued to the required 105 foot pounds, The flywheel hub will expand to tightly grip the crankshaft. For this reason, this is one of the most difficult flywheels to remove. Standard quarter twenty bolts will break. Schedule 8 bolts must be used.

If less torque is used, moisture can creep in and as iron expands as it oxidizes, the rust will weld the two together. Less torque will shear the key, which was never designed to hold the flywheel. Many have lapped the damaged flywheel to the crank to avoid the cost of new parts. It will be very difficult to get the tight grip of the original coupling. It will involve using more compound at the top of the crank to get the proper taper. Yes, heat is often needed.

I recall one motor I had worked on for an hour with a strap wrench, heat and penetrating oil. I decided to take a lunch break and when I slammed the shop door there was a loud report. When I checked to see what had happened, I found the flywheel had popped loose with such force that it was now balanced on TOP of the crankshaft. So, had I just lifted the flywheel and tapped the center bolt one more time, it would have come loose. However it may have ended up on the floor . . . . 😆

[frankr]

That isn’t even one of the most difficult ones. The 1962-up had a bigger shaft. Anyhoo, the only ones I have ever been unable to remove were where some fool had put Locktite on the tapers. As Garrry said, use Grade-8 bolts, and screw them in 7/16", no more and no less. The bolts thread into the steel hub and should not pull out. Use your flywheel puller and give it heck. If the puller breaks, get a better puller.

[auldscott]

Might be a long shot, but try the hot wax method: warm the flywheel enough to melt candle wax (remove the heat source first) into the joint. Let cool. Warm again, and try your puller/knocker. It might take several attempts.

[joecb]

A suggestion… when you "whack" that puller to try to break loose the flywheel be sure that someone is lifting up on the flywheel and the nut is still in place buy loose a few threads. On a really stubborn wheel the lifting part can best be done by supporting the weight of the motor with two lengths of 2X4 under the flywheel rim and extending down to the concrete floor.

Joe B

[outbdnut2]

Thanks for the info guys! I’ll have to check just what grade bolts I have in my puller. A year ago I asked my local hardware store for the strongest bolts they had, but never checked what the grade was. When I know I have grade 8, I’ll tighten the puller more…..and I’ll try some heat too.
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Just a thought – would it help to put an air impact wrench on the puller center bolt? Will that repetitive shock force help? It will solve the problem of the flywheel turning while I tighten it. I use the air impact wrench to loosen flywheel nuts, and it takes them right off without holding the flywheel.
Dave

[lindy46]

I just had a stubborn one like that and an impact wrench took it right off. Make sure to leave the flywheel nut on loosely.

[fleetwin]

I hope you are using the OMC puller, which has the good bolts and solid disk, most other pullers just aren’t strong enough to do the job, the puller will bend/yield/break before that flywheel gives way. But, more importantly, you run a real risk of being badly injured using some other type/style puller.
I certainly can not provide anymore info that Frank and Garry have already supplied, except to agree that a big impact gun may help, but only if you are using the OMC puller.

[outbdnut2]

I don’t have the OMC puller – I use a cheapie Harbor Freight bolt puller. I did some searching online and found several places selling OMC 0378103 puller. It looks heavy duty. I will order one since I have 7 or 8 old 35-40 HP OMCs here.
Thx for the info.
Dave

[vintin]

quote outbdnut2:

I don’t have the OMC puller – I use a cheapie Harbor Freight bolt puller. I did some searching online and found several places selling OMC 0378103 puller. It looks heavy duty. I will order one since I have 7 or 8 old 35-40 HP OMCs here.
Thx for the info.
Dave

I anyone has this puller for sale I’m in the market for one. Please PM me details.

Thanks,

Dan

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