MS 660 Smells Hot!

[stappe]

Hi All, new to the site. I recently bought a Stihl MS 660 that had been used pretty hard. Had a recent tune-up from our local Stihl dealer. It runs great, cuts well, but gets awfully hot. It has that hot metal smell to it after a few minutes of bucking and limbing. I spent a lot of years running 044, 046 440, 460 in my wildland firefighting days and I can’t ever recall a saw feeling and smelling that hot.
Any thoughts on what I might have going on?
As I said, saw was very dirty, like it hadn’t been torn down in a loooong time and cleaned. I’m in the process of doing that right now. I appreciate any wisdom y’all are willing to provide.

 

[mattr66]

If it is too dirty to flow air around the cylinder, that may be all it is.

Sent from my motorola edge plus using Tapatalk

 

[cscltd]

My wisdom would be dont go to that “Stihl?” dealer. If they tuned it up as you say unless you (forgive the comment) said just get it running only for least $ and presumed that meant tune up, they should have pulled covers and clean or scraped off dirt buildup on fins and around flywheel area.

 

[Old2stroke]

You better hope that the Stihl dealer doing the tune up, didn't set the high speed carb adjustment too lean. Was the saw running hot before the visit to the dealer, and then started to run hot as soon as you got it back?

 

[stappe]

This saw was brought to dealer by it’s previous owner for maintenance, including tune up. He skipped out on the bill and never returned for the saw so the owner of the dealership took it home and had been using it.
I went in to the shop looking for a 362. We got to talking about older model Stihls and he mentioned this 660. I asked if he’d sell it and he said he would.
So this week is the first time I’ve used it and noticed the heat and smell. It does have a new spark plug, and the bar and chain are both like new. I checked the spark arrester and the screen was clear.

 

[FamilyTradition]

I'd first remove the muffler and check for scoring and check carb needle settings as suggested above. Pictures of how dirty the saw is would be helpful to show just how dirty it is and to generate more feedback. If the piston looks good my suggestion is to remove the covers and get "toothbrush close" on the entire saw. Compressed air, some type of cleaner, whatever works best for you. I'm not a proponent of power washing, but others here are and that's fine. Once clean run it and see if the smell is still there. If so, reach back out. Best of luck, Max.

 

[stappe]

I'd first remove the muffler and check for scoring and check carb needle settings as suggested above. Pictures of how dirty the saw is would be helpful to show just how dirty it is and to generate more feedback. If the piston looks good my suggestion is to remove the covers and get "toothbrush close" on the entire saw. Compressed air, some type of cleaner, whatever works best for you. I'm not a proponent of power washing, but others here are and that's fine. Once clean run it and see if the smell is still there. If so, reach back out. Best of luck, Max.

Thank you, Max. Pulled muffler and piston looks great. Attached a few pics. The fins are after one round of scrubbing. You can get a sense of how dirty this thing was from the pics of the clutch side. Got a few new parts coming in tomorrow hopefully. I’ll fire it back up then and see what I’ve got. Appreciate your suggestions.

 

[Pepster]

Clutch?

 

[stappe]

Clutch?

Yep. Right under the clutch drum there.

 

[Pepster]

I've had the clutch bearing run dry in the past & got that "hot metal" smell.
It's often a over looked maintenance point.
Might check it out because it should be a regular maintenance component.

 

[stappe]

I've had the clutch bearing run dry in the past & got that "hot metal" smell.
It's often a over looked maintenance point.
Might check it out because it should be a regular maintenance component.

Ah, I apologize. I thought you were doubting there was a clutch on the saw… Sometimes I’m slow. Thank you for the suggestion.

 

[Pepster]

Is it rim drive clutch?

 

[stappe]

Is it rim drive clutch?

Yes. I pulled it out earlier tonight. Bearing is almost new, rim drive is in good shape, clutch looks good. Only difficulty was getting the washer off after I removed the eclip. Washer took some muscle to remove. Not sure if that means anything or not.

 

[Pepster]

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Mucho hard to troubleshoot over the net with only a smell to go bye.
Oiling good?

 

[stappe]

I

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Mucho hard to troubleshoot over the net with only a smell to go bye.
Oiling good?

I understand. Oils well. The heat and hot metal smell were coming from the muffler/cylinder area. Obvious places to be hot, I know. I just can’t recall running a saw and having it smell that way.

 

[Pepster]

Bearings have that "hot metal" smell.
Hate to be the one with tough love.

 

[Clyde85]

You should be able to hear bad bearings if you pull it over slow with the plug out.

 

[Pepster]

Clutch off & shake the shaft side to side.

 

[Pepster]

Everyones hearing is different.

 

[Clyde85]

Everyones hearing is different.

That is true. Mine isn't what it used to be.