Stuck flywheel

[brandonstc6]

I have a stihl 08s chainsaw i am working on. It has no spark. I am trying to remove the flywheel. I have put a lot of pressure on the flywheel with my puller and it will not budge. I am afraid to put too much pressure on it. Is there anything I can do to get the flywheel off. Thanks

 

[Pioneer]

While you have it tightened down, rap the center of the puller hard with a hammer at the point where you normally apply the wrench. It should release with a loud 'pop'. I almost always have to do this when I remove a flywheel, some can be very stubborn.

 

[undee70ss]

While you have it tightened down, rap the center of the puller hard with a hammer at the point where you normally apply the wrench. It should release with a loud 'pop'. I almost always have to do this when I remove a flywheel, some can be very stubborn.

X2! I have never had one not come off using this method.

 

[hotshot]

You need to take the nut off the crankshaft first

Counterclockwise loosens it, even on a Stihl

 

[brandonstc6]

You need to take the nut off the crankshaft first

Counterclockwise loosens it, even on a Stihl

The nut has been removed already


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[CM76]

If the flywheel is particularly stubborn on its taper, you can try and apply a gentle amount of heat to the flywheel to expand it whilst it is under tension with the puller.

Chris

 

[happysaws]

If hitting the end of the puller while the flywheel is warm still will not get the flywheel off, mix up a 1:1 ratio of automotive transmission fluid and acetone, put a drop or two on the crankshaft, let it sit overnight and try again. It will come off.

 

[brandonstc6]

I tried the hammer method and it still would not come off. I guess I will try soaking it with something next.


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[sawfixer]

When I can't get the puller to work, I go to the "knocker" method. Make sure you thread on the nut a few turns to protect the end threads of the crankshaft (I sometimes use a sacrificial nut) and then you must insert a tapered steel wedge (I use a large flat bladed screwdriver) between the flywheel and crankcase. This wedging is what drives off the flywheel. I then use a large flat ended punch and give a short but sharp tap with a hammer and usually the flywheel will come off on the first hit. Sometimes it will take additional strikes. This can put stress on the crank and bearings and not the best method but sometimes it's the only way to get the flywheel off.

 

[happysaws]

I tried the hammer method and it still would not come off. I guess I will try soaking it with something next.


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Was the flywheel heated up when you tried the hammer method?
Heat it up till you can't grab it with your bare hand, put on a really heavy duty glove, pick it up by the flywheel and give it another whack.

 

[Okie]

If the flywheel is particularly stubborn on its taper, you can try and apply a gentle amount of heat to the flywheel to expand it whilst it is under tension with the puller.

Chris

Leave a flywheel nut loose 2-3 turns on the crank because you will expand the end of the crank or ruin the threads without such. Use gentle heat while the flywheel puller has good pressure, just enough heat at the center part of the flywheel that you can still hold your hand on the center of the flywheel. Give the center puller bolt of the puller a good sharp rap with a hammer (I use a brass hammer) and re-snug the puller. If no go apply 50/50 mix of acetone and auto xmission fluid around the crank and let soak overnight. Gently warm (the acetone and oil is flammable) the flywheel again and just walk away with the puller under good tension. I sometimes use a heat gun, but a hair dryer is better than nothing. I've been doing other things just letting it sit under puller tension and hear the flywheel pop loose. The heat/cool of the aluminum flywheel will make it turn loose. I also have a propane torch that has a small pencil tip flame that is good for the heating right around the center of the flywheel. Do not get it too hot. When you cannot quite hold your finger on the center of the flywheel it's WARM enough.

I've seen some tough ones. Be patient. You have to get a feel for how tight to get the puller without ruining things.
The heat and patience is your friend in this instance. I do not use the whack and pry method when a puller can be applied.
Make sure the puller is NOT PULLING SIDEWAYS. You need a even pull on each side. After it comes off gently polish the taper on the crank gently with emery cloth and clean off the penetrating oil before re-installing.
Do not oil the taper before re-installing or the flywheel key may shear. The dry taper is what keeps the flywheel secure, not the key. The flywheel key is just to keep the flywheel timed properly.

 

[super3]

Had one on an 090 that I had soaked with different solutions for over 2 weeks. Wouldn't budge with the puller and hammer trick. Heat made no difference.

Was discussing it at the local saw shop with the owner, he said try a plastic hammer on the puller bolt. I gave him a look and he said "yep, I know but that's what the old Amish feller with a shop a couple of towns away uses and it works for him."
The other shop guy said to use Sea Foam Deep Creep.

I propped it on it's side and prayed on the Deep Creep and let it sit overnight. The next morn it had soaked in(only solution to do so). put the puller on with medium pressure and one whack with the plastic hammer and it popped right off.

Whether it was the Deep Creep, the plastic hammer or a combination of all previously tried, I didn't care.

Regardless I'll try the Deep Creep and plastic hammer first on the next tough one.

 

[stevetheboatguy]

Probably not kosher........ But I know a local mower and saw guy that uses a small zip gun to knock them loose. I've never tried it, but I have seen him do it to many. Spin the nut on to protect the threads but leave it loose from the flywheel. Take the zip with a round hammer in it. Hold the saw by the flywheel and give the crank a quick hit from the zip gun. Never seen him fight one.


Steven

 

[Okie]

Probably not kosher........ But I know a local mower and saw guy that uses a small zip gun to knock them loose. I've never tried it, but I have seen him do it to many. Spin the nut on to protect the threads but leave it loose from the flywheel. Take the zip with a round hammer in it. Hold the saw by the flywheel and give the crank a quick hit from the zip gun. Never seen him fight one.


Steven

I've never tried my zip gun (air impact chisel) on a flywheel but I have it rigged with a adjustable air regulator and a blunt hammer end and can set it on a rusty stuck bolt and adjust the air pressure up slowly to where the air chisel just hums and vibrates without actually hammering and break the rust loose around the threads. The air pressure can be adjusted to where the air chisel just sings (like a wood bee) when held tight against a object and you can see the rust breaking loose and this also breaks up rust and crud around the threads allowing penetrating oil to soak in.
I'll have to try the air chisel instead of the big hammer whack/pry method.

 

[Jim Foote]

I've never tried my zip gun (air impact chisel) on a flywheel but I have it rigged with a adjustable air regulator and a blunt hammer end and can set it on a rusty stuck bolt and adjust the air pressure up slowly to where the air chisel just hums and vibrates without actually hammering and break the rust loose around the threads. The air pressure can be adjusted to where the air chisel just sings (like a wood bee) when held tight against a object and you can see the rust breaking loose and this also breaks up rust and crud around the threads allowing penetrating oil to soak in.
I'll have to try the air chisel instead of the big hammer whack/pry method.

@Okie - great tip - thanks!

I had a stubborn one today - the winning strategy was a combination of several ideas posted above and in other threads. After failing with a threaded flywheel puller (puller did it’s job, but flywheel threads stripped out), and the ‘hold the flywheel and hammer on the shaft+nut’ technique:

PB Blaster, wait 5 min,
Thread on flywheel nut, slightly proud of the shaft, still well off the flywheel
Position flywheel with magnets adjacent to centerline of the cylinder body
Wedge a flat headed screw driver between cylinder and flywheel to provide mild tension
With air pressure set to near minimum to drive the air impact chisel:
Chisel with point bit on shaft detent to set up vibrations to help the PB Blaster
20 seconds of vibrating and the flywheel popped loose

No telling which step was actually key! But I’ll try this again next time.

Lots of good ideas in this forum - thanks to everybody for the tips.

 

[Okie]

Jim Foote:

For flywheels, the tough ones, I have a propane torch that has a pe3ncil tip flame and I can easily control the direction of the flame and I apply heat around the outer part of the flywheel just out from the crankshaft. I try to direct the flame where the flywheel expands faster than the crankshaft. I have the puller attached while doing the heating and then rap/tap the center puller bolt of the puller and snug it up again and rap/tap again.. Heat/cool is your friend. I do not get excessively hot just good warm. If you drip a drop of water on the area or spit on it and it spits back that is getting too hot. I also have a Oxy/acty torch but I do not use it because it can get too hot too fast. You have to have a feel for things when doing the pulling with a puller to keep from breaking and stripping things. I have used the rap the flywheel nut with a wedge under the flywheel but I hold up on the block when doing so, so as any end play of the crankshaft is using the block as additional inertia force. (other end of crankshaft is not resting on anything. I do not prefer the BFH hammer and wedge routine for the really tough ones due to too much hammering.
I have warmed them and if it don't give up just walk off let it cool and go back later.
Heat and cool under pressure and they will eventually give up. I have heard them pop loose as they are cooling.

Patience is your friend.