Cutting Off a Flywheel? 1974 Johnson 4HP

[Doolin]

Hi all,

I've got a seriously stuck flywheel. I followed advice here and got a harmonic balancer puller and 3", grade 8, 1/4 X 20 bolts. When it took all the torque I could muster with a 2' breaker bar I looked here and saw a suggestion for Transmission Fluid and Acitone as a penetrant that had worked for others.

Over a 2 day period I applied the penetrant and further snugged up the main puller rod with an impact hammer.

I continued doing this until the Grade 8 bolts busted. The end of the crank shaft also shattered in the process.

So, I'm ready to take the die grinder to spit it from the side to center... unless someone has a better idea?

Also, anyone have a flywheel for a 1974 Johnson 4HP for a reasonable price?


Thanks in advance for any help you can offer,


Ben

 

[tashasdaddy]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

i have had them take a week to come off.

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

And I thought I was being patient.

Any options to cutting it off?

 

[jonesg]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

there are better ways than destroying it.

drill a 1/4 inch hole next to the hub to relieve the pressure, after its removed tap the hole 1/4 x 28, using red loctite screw a 1/4 x 28 bolt in and cut if off flush. Be aware you need to follow the taper of the shaft with the drill.

I would retry the puller ....with the blue wrench before drilling.

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

The blue wrench?

2 of the 3 Grade 8 bolts broke off just inside the flywheel. There was about 1 1/4 inch of threaded section on the bolts... where the threads stopped is where they broke.

Not sure I'm going to be able to get those out to try the puller again.

 

[cadet917]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

maybe try putting a bolt back in the crank and weld a nut to the top of it in an attempt to get the corrosion to ash?

 

[samo_ott]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

You said the end of the crankshaft shattered? If it's toast then there's not much point in taking the flywheel off unless you're planning a full rebuild.

I've had the 1/4" holes strip before... Re drill and re tap to 5/16" or 3/8" if need be. I have a '54 J25hp that has one 1/4" hole, one 5/16" hole and one 3/8" hole. It will come off eventually. The bigger bolts grip a lot more.

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

Yes, the end of the crank shaft did shatter... but the threads are good about 1/8th of an inch. I'm hoping to be able to grind off the bad section and still have a good grip with what's left. Should be close to 1/2 inch left.

The Grade 8 1/4 inch bolts are broken off in the holes... I don't think I'm going to be able to get those out.

I did as one of the previous posts suggested to drill along the shaft to relieve the pressure. I then drilled 2 new 5/16 holes for new bolts to use with the puller. I applied more penetrant and put some pressure on the puller.

I'll be patient this time

 

[atengnr]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

Can you get some heat on the flywheel to open that pilot diameter? Not sure if this could be done without damaging coils, etc.

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

I think I'll try that in the morning. I'm not too concerned about the contents underneith... they must have been stuck under there for so long that it's time for new anyway.

Thanks for the suggestion.

 

[F_R]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

I think I'll try that in the morning. I'm not too concerned about the contents underneith... they must have been stuck under there for so long that it's time for new anyway.

Thanks for the suggestion.

When it's all said and done, I'm betting some yeahoo put locktite on the tapers. It takes about 300 degrees to soften Locktite.

 

[jonesg]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

The blue wrench...propane torch.

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

Ah.... Yeah... I'll give that a shot. I assume the crank shaft should get the heat... so it'll expand... then shrink as it cools loosening it's grip on the flywheel?

Or maybe the other way arround... heating the flywheel so that it expands?

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

How long should I heat it for?

I've seen aluminum melted with a propane torch... I'm also sure that 'not enough' is a total waste of time.

I hit both sides for about 2 minutes each. I just have no idea if that's in the 'not enough' range or close to the 'too much' range.

 

[R.Johnson]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

Using the correct puller bolt's will save a lot of grief such as this. I have mentioned that you need a shouldered stripper bolt, with a 1/8" tempered washer time, and again. In fact! just a couple of pages back. These are the bolt's OMC use's, and sell's infact. A wrong bolt will break, or pull out the thread's because of improper grip. Take a grade 8 bolt to a ficht flywheel, but get your check book out. If you can end up with a 1/2' of thread on this small engine, you should be alright.

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

I did a lot of searching and reading on iBoats before I started pulling. In fact everything I did was based on suggestions here (thanks everyone for the help). I wish I'd read your suggestion on type of bolt to use. I went with Grade 8 based on suggestions here... but those broke.

I've never even heard of the bolt you suggest... but I'll be looking them up.

Any suggestions as to how much heat is too much? I've heated and allowed to cool once (2 minutes from each side) and it's still stuck on there.

 

[tx1961whaler]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

I did a lot of searching and reading on iBoats before I started pulling. In fact everything I did was based on suggestions here (thanks everyone for the help). I wish I'd read your suggestion on type of bolt to use. I went with Grade 8 based on suggestions here... but those broke.

I've never even heard of the bolt you suggest... but I'll be looking them up.

Any suggestions as to how much heat is too much? I've heated and allowed to cool once (2 minutes from each side) and it's still stuck on there.

If you broke off grade 8 bolts, then there are other issues involved.

 

[rockyrude]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

Just run your torch in a circle maybe 1/2" away from the crank, make sure you have the puller on it with plenty of pull. At some point, it will pop off. Two minutes isn't nearly enough time and I doubt you need to worry about melting it.

 

[R.Johnson]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

I just thought. you have a flywheel cracked out at the center hole, Do you know someone with a lathe to make you a centered bushing to slip over the crank shaft

 

[Doolin]

Re: Cutting Off a Flywheel? 1974 Johnson 4HP

>>If you broke off grade 8 bolts, then there are other issues involved.


Yeah... it's REALLY STUCK!

I read when searching that there was a commonly used product (lubricant?) that was... I think they said Carbon based... that would effectively bond metal parts together. Not sure if that's the case here but the motor is old enough. And however it happened... it's 'effectively bonded'.