2013 MS660 flywheel issues.

[Dieselshawn]

Hello fellas, I’ve got a 2013 MS660 that I’m trying to get running.

I was given a couple parts box of several MS660’s and 661’s from my logging buddies.

(they needed storage space in their shed)

They said I can put a 660 and a 661 together if I wanted with the many parts in the spare parts boxes.

So I found a 660 in the box that doesn’t look like it needed much to get running.

Has a poly flywheel on it but wasn’t tight to the crank. Key was sheared.

I put a new key in and torqued it down. After 3 passes on the dyno, the saw shot a blue flame and shut down. I heard spinning noises. The flywheel came loose again.

While looking it over, the taper of the flywheel and crank doesn’t seem to match. It’s loose.

Here’s the serial number for the 660

175771283.

I’m told there’s maybe 2 different style of flywheels?

 

[jacob j.]

I'm not aware of two different poly flywheels for the 660 family, but of course there were the metal flywheel saws which have a much different taper on the stub shaft. What size is the flywheel nut on that crank?

 

[Dieselshawn]

I’ll have to check later. Saw is at home.

So this could be a metal flywheel saw

 

[066 redeye]

Metal wheel is M8 nut.
Poly wheel is ,m10 nut.

 

[Dieselshawn]

Would there be a part number for the metal one?

 

[066 redeye]

Part numbers on the back of the fly wheel.

 

[066 redeye]

sorry wrong pic.

 

[Dieselshawn]

I’m hoping to have a part number for correct flywheel so I can find one.

Stihl dealer doesn’t have one in stock for me to try and verify it’s correct

 

[066 redeye]

Need nut size on your crank first.
To confirm wheel type.

 

[DND 9000]

You need the 1122 400 1202 flywheel for your saw.

 

[Dieselshawn]

I haven’t had a chance to look at my 660 yet. Been busy at work.

 

[Sawyer94]

When it’s on the dyno does it go under any load? Had one do that recently running no bar and chain, shot a flame and sheared the key.

New key, bar and chain and it hasn’t gave me any issue yet. Should’ve known better to tune a saw without it wearing its bar and chain. Tisk tisk.

 

[Dieselshawn]

The dyno is already a bar and chain powering a hydraulic pump

 

[Dieselshawn]

I just checked the 660’s threads with thread size gauge for crank and nut. It’s a 1.0 thread but I have nothing in my set that fits. The M10 die I have is only 1.25 and doesn’t fit.

The M8 1.0 is too small. Awfully small to be used on any saw anyways.

The nut uses a 17mm socket for install or removal.

 

[jacob j.]

It sounds like you have a poly flywheel crank, based on the flywheel nut size.

You might try finding another poly flywheel or you can try the aftermarket aluminum flywheels available for that crank
(I don't recommend aftermarket flywheels though).

If you find another poly flywheel and still have fitment issues with it, you can try lapping the flywheel to the crank.

 

[Dieselshawn]

I have tried another poly flywheel and it was the same problem. The one the Stihl dealer had in their parts room was worse than the flywheel that was on the crank when I pulled it out of the parts box.

Thought about lapping the flywheel to the crank.

 

[stumpyfine]

The last saw I had that did this,it was caused by one of the dowel pins coming loose and getting tangled in the oil pump drive, this causes a momentary shock shearing the key, at the same time the pin or whatever is loose gets thrown out of where it jamed and lurks in the shadows while you replace the key,The saw then starts and runs fine until the pin or whatever jumps out and catches again,repeating the process
I suggest pulling the clutch off and checking that side of the case for stray parts
This may not be the problem, just something I would check.

 

[Dieselshawn]

I’m just amazed that the saw would have flywheel fitment issues.

Unless I have a bad flywheel and the dealer had a bad flywheel.

It’s obvious the saw is not gonna run with a loose flywheel which I’m wondering how it would cause fitment issues.

 

[stumpyfine]

Sorry probably not making myself clear, (Irish heritage) when the crank jams,the flywheel spins on the crank.shearing the key. This can distort the taper so it doesn't fit properly.

Are the tapers radicly different or just slightly and could be corrected by lapping?

Also check that the nut dosent bottom out on its thread before it clamps the flywheel tight, highly unlikely, but something I would check.

I will get some dimensions of the tapers that I have and post them here

 

[Dieselshawn]

Thank you, I’ll check again.