Stihl 088 persistent melting problem!

Hey everybody, from the highlands of Papua New Guinea!

I'm a motorcycle and small engine mechanic from the US living and working here in PNG. I've got a Stihl 088, (I guess it's also called an MS880, but it says "088" on it--maybe I'm reading it upside down?), anyway, this saw comes into my shop after every few hours of use with the same problem--the clutch needle bearing cage gets too hot and melts. It must get really hot, as the plastic gets slung everywhere and really gums things up. The last time it was in, I took the collected needles from 2 previously melted bearings and made up one "cageless" bearing. This solved the problem of melting doen the bearing cage, but now it's back again because the oil pump drive gears (also plastic) are melting! The problem manifested itself this time by the bar and chain being too dry--when I got into it, I found that the friction drive spring for the oil pump gears wasn't doing its job because the plastic gear that it mounts on was melted away, hence nothing for the friction spring to grab. Everything else appears to be okay--the saw starts easily (for such a big saw), and the carb appears to be properly tuned.

I'm tired of pulling my hair out over this one and would appreciate any help anyone can give me. Is there anyone out there who makes metal oil pump drive gears for these?

Thanks.

How does the clutch look? If it’s three shades of blue it’s probably operator error.

Yeah, I thought of that, too. At first I thought the problem was due to the owner turning the saw over to a gang of local tribesmen to use and them running it with the brake on, but the owner says that they never use it without his close supervision, and that they don't ever try to run it with the brake on. The clutch is not 3 shades of blue, (the clutch doesn't look like it's been overheated), but I was surprised at how dry the bearing was--I remember using a good grease on it, but when I cracked it open this time, it was completely dry. Which begs another question--how is the clutch bearing normally lubricated? Just
grease?

Oh, and the brake isn't dragging either--already checked that the last time it was in my shop.

I really work on motorcycles a lot more than I work on saws, so any help is appreciated.

If you look at the inside of the clutch drum and it has a mirror finish where the clutch shoes engage, It's glazed. Change the drum or rough it up with some emery cloth. If the shoes have left a grove in the drum that you can feel, change it.

Thanks, Grande--no mirror finish, but there is a "finger feelable" groove. What would have caused this on a saw with less than 50 hours on it? How long should I expect a clutch to last on a saw like this? Would this be the cause of the melting plastic bits?

Sounds like the oilier might not be working, causing the bar and chain to heat up then heating up everything else. Watch out for the crank seal and make sure it does not get damaged.

Oiler quit working when the drive gear melted. Why did the drive gear melt?

Maybe it was run without oil? More likely, your clutch is overheating for whatever reason, and melted the gear.

Lakeside53--not run without oil, there's no damage anywhere else. The saw starts and runs just fine, great compression, easy start, etc. The only problems are in the clutch area.

Somebody earlier mentioned operator error--could anybody edumacate me on what operator error overheats a chainsaw clutch? Especially on an auto-oiling saw.

Dogging it in with a dull chain.

By "oil", I mean bar oil.

Lakeside53 said:

Maybe it was run without oil? More likely, your clutch is overheating for whatever reason, and melted the gear.

Click to expand...

Thats what Im thinking,,, :agree2:

Replace clutch drum, bearing, worm drive, fill unit with bar oil and start it with
clutch cover removed and just idling,,,, the clutch should be spinning and make a real good puddle of oil!!!!!!

I'd also replace the clutch springs...Doesn't take long on an 088 to overheat the clutch... if it's run by idiots.

I got mine because of a idiot..:greenchainsaw:


and... grease the new bearing...

Oh, right, bar oil. Lakeside53, sorry mate, I misunderstood you.

It'll take me a little while to get the parts for this thing out here, but right now I am planning to replace the clutch drum, the melted gear, and now also the oil pump, as I just pulled it off and it feels hard to turn. Shouldn't it spin fairly easily? I'm planning to keep my new cageless clutch bearing, however, as it looks good and I like the idea of it.

After I get the parts here and installed, I'll try the "start it with the clutch cover off" test and see if oil comes out. It still seems weird to me that we keep having the same problem over and over--I could understand it happening once, but 3 or 4 times? Does this stuff melt immediately once the bar oil runs out?

I was thinking of slack clutch springs, but he said the clutch wasn't blued from operational "retempering." How long would a saw run without bar oil (esp. in rainforest rosewood, etc.) before welding the drive links to the bar? That would be a heckuva "chain break."

Good luck getting it figured out!

You haven't said but I am guessing it has a 6 foot or better bar. The clutch is really not suppossed to slip. When it bogs, runs a real long bar at part throttle, or the operator is on and off the throttle while the chain is not turning or turning slowly (operator error) the thing gets hot and real hot in a hurry. Just because the owner is observing the operator doesn't mean that he knows how to run it correctly.
If the drum is scored then the shoes may be rounded and not making full contact. Check with a straight edge. Keep any oil or grease off the shoes/drum. Mike

JungleBiker said:

Oh, right, bar oil. Lakeside53, sorry mate, I misunderstood you.

It'll take me a little while to get the parts for this thing out here, but right now I am planning to replace the clutch drum, the melted gear, and now also the oil pump, as I just pulled it off and it feels hard to turn. Shouldn't it spin fairly easily? I'm planning to keep my new cageless clutch bearing, however, as it looks good and I like the idea of it.

After I get the parts here and installed, I'll try the "start it with the clutch cover off" test and see if oil comes out. It still seems weird to me that we keep having the same problem over and over--I could understand it happening once, but 3 or 4 times? Does this stuff melt immediately once the bar oil runs out?

Click to expand...

No... it almost mever melts, and certainly not "as soon as the oil runs out". Your problem is most likely the operators...


Put the OEM caged clutch bearing back in. If everything is correct, you'll never melt it. A home-grown "cageless" will NEVER have the requried clearence and accuracy... next you'll be replacing the crank...

Hmmmm. I'm thinking that you are most likely right--the operators are most likely the problem. However why is it that I don't see the same problem with other saws under the same kind of conditions? I see mostly Stihl 090's and Husky 3120's and they never seem to have these kinds of problems. Are the Stihl 088's just more susceptible to operator error?

While I respectfully disagree with you on the cageless bearing idea, I will nonetheless bow to your superior amount of experience and order a new bearing. Sigh.

There is nothing in an 088 that make it more susceptable to "abuse".

The problem with a cageless design is that you cannot hold position on the rollers, and that means a change in axial displacement. And... there is the problem of cleaning and regreasing a bunch of fiddly parts.

JungleBiker said:

Hmmmm. I'm thinking that you are most likely right--the operators are most likely the problem. However why is it that I don't see the same problem with other saws under the same kind of conditions? I see mostly Stihl 090's and Husky 3120's and they never seem to have these kinds of problems. Are the Stihl 088's just more susceptible to operator error?

While I respectfully disagree with you on the cageless bearing idea, I will nonetheless bow to your superior amount of experience and order a new bearing. Sigh.

Click to expand...

Yeah, I'd listen to Lake.

I've never seen an 090. You say they are rugged like a 3120, is the clutch internal or external on an 090?

Lakeside53 said:

There is nothing in an 088 that make it more susceptable to "abuse".

The problem with a cageless design is that you cannot hold position on the rollers, and that means a change in axial displacement. And... there is the problem of cleaning and regreasing a bunch of fiddly parts.

Click to expand...

DOes that mean the little rollers will twist in their space between the spindle and the tube, and thus wear out the outer edges of the clutch drum tube?

This may be a ridiculous idea, but is there a saw model whose wrist pin bearing (metal cage) has the same dimension as the 088 clutch bearing? Jest a thought..............


Oh, and yes, I would listen to Lake, aka the Keeper of the Flame, as well.........though I did do sum cowboy stuff splitting an 036Pro case once........