Replacing the Flywheel Nut?

[KVH]

My manual says that when you remove the flywheel you should "replace" the flywheel nut, a nyloc nut, with a new one.

Is that a bit overkill if it's only been removed once before? Is it really necessary to buy a new one? 200 hp Evinrude. thx

 

[Daviet]

Re: Replacing the Flywheel Nut?

Never heard of it before, but I don't work on those engines. It might be something special for that engine, I am sure someone will come along and confirm it.

 

[jimmbo]

Re: Replacing the Flywheel Nut?

A lot of fasteners are one use only. If the manufacturer says replace they must have their reasons. Either the worn nylons allows the nut to back off, or it affects how stressed the top of the crankshaft gets when the flywheel is tightened down. Too tight and the crank can crack

 

[KVH]

Re: Replacing the Flywheel Nut?

What's that saying about advice no one likes to hear? OKAY, off it comes and back to the order desk!

 

[woody66912]

Re: Replacing the Flywheel Nut?

No you don't, That's just engineering side talking. Remember they work in a world of numbers and theory, I have these off and on many times.

 

[jimmbo]

Re: Replacing the Flywheel Nut?

That's just engineering side talking.

Yeah, what do they know about the engine they designed?

 

[woody66912]

Re: Replacing the Flywheel Nut?

OK hear is a test. If you can spin that nut all the way down by hand then the nyloc is toast.

 

[boobie]

Re: Replacing the Flywheel Nut?

I've always used blue loctite on them, torqued to the PROPER Spec and never had a problem.

 

[clanton]

Re: Replacing the Flywheel Nut?

What kind of manual do you have, after market or OEM? 1995 OEM manual does NOT require nut replacement. Crankshaft and flywheel taper must be clean and dry. Coat threads of flywheel nut with OMC gasket sealer, torque to 140-150 ft.

 

[MikeB0307]

Re: Replacing the Flywheel Nut?

I'm with boobie, loctite is your friend. As Woody said, if you cannot spin it down by hand, nylon is ok, add a bit of loctite and torque to spec. Run it up to temp, let her cool back down and verify torque if your worried. But one you loctite it and torque it, it'll be fine.

 

[KVH]

Re: Replacing the Flywheel Nut?

The manual I have is after-market, SELOC.

I lubricated the upper crankshaft a bit, but it was already a bit "lubed" from the head bearing assembly I'd just re-installed. I then fit the flywheel on and tightened to 140 lbs per the manual.

Then I noticed that my manual had said in ALL CAPS 'NEVER' to re-use the nyloc nut. It says a new one must be used, along with gasket sealant. So, being neurotic, I've removed it and I'm ordering a new one. I tend to agree with those of you who say that is overkill. At 140 lbs torque, I'd also tend to think that blue thread lock might make it nearly impossible to get that thing back off. I think gasket sealer is a good idea.

Thanks for the help.

 

[KVH]

Re: Replacing the Flywheel Nut?

OK, I put the flywheel back on. The nyloc part was still good and the nut is tight, with a bit of loctite.

I'd like not to be a worrier, but two questions. First, I see some play in the flywheel as I rotate it. There is about 1/64th play at the woodruff key. The key looked good. The flywheel has been off once in its life, and I looked at the key--it seemed fine. Is that play OK?

Next, let's assume the worst. If that nyloc nut were to loosen up, can I assume I'll know it before it saucers out of the cowl and heads for my boat guest? I can't believe that there is some kind of sudden catastrophe.

Thanks.

 

[jimmbo]

Re: Replacing the Flywheel Nut?

I was riding in my dads boat in 1974. a 1963 40hp Johnson. My grandpa and were going along at a blistering 25mph. I was faced backwards. The motor suddenly flipped forward about 1/2 way up like it had hit something and quit. I lifted the engine up and saw no damage to prop or skeg. I lowered the moter and restarted it. well now it had no power and then it quit and wouldn't crank. We got a tow back and put the boat on the trailer. My dad spent some time looking at it and determined the flywheel was jammed up against the recoil starter. He removed the recoil and I remember looking at flywheel nut sitting at the top of the crankshaft, the top a little chewed up. I reached for it and I only had to turn it less than a 1/4 turn and it lifted off. If the recoil had not been there I'm pretty sure the nut would have come off completely and the flywheel would have been in the lake or in the boat. I doubt a fiberglass cowl would have contained it.