Stihl 088 persistent melting problem!

[JungleBiker]

Ordinarily I would agree 100% with Lake on the bearing thing, but I have found that there is a number of rollers, (can't remember the exact number right now as I don't have it in front of me), but there is a number of rollers that is a very nice fit in the space available. But nevermind that, it's off the subject a bit.

The 090's I see here are manual oilers, so maybe that's why they don't have oil pump problems! It's been a while since anybody dragged in a 3120, so I can't remember if they are auto-oilers or not, but I do know that although I have seen clutch problems on the big Huskys, (definitely operator error that time), I've not seen oiler problems. I have seen a little top handle Husky, (335 XP, I think?) that had the teeth stripped off of the oiler drive, but that one had lived a long, hard life full of abuse. I ended up replacing the crank/rod/main bearing assembly, the piston and rings, the oil pump and drive, carby diaphragms, clutch, pullstarter, etc., etc. Turned out good in the end. Nice little saw. New saws are terrifically expensive here, so the owner thought it was worth it to basically fill the cases with new bits.

Back to the 088--has anybody else out there ever melted down the oil pump drive gears and the clutch bearing cage for ANY reason?

 

[brncreeper]

The 3120 has an automatic oiler with a manual oiler assist. Also, the 3120 has an external clutch. The 084 also has an automatic oiler with a manual oiler assist, too bad the 088 didn't get the manual assist too.

 

[2dogs]

Ordinarily I would agree 100% with Lake on the bearing thing, but I have found that there is a number of rollers, (can't remember the exact number right now as I don't have it in front of me), but there is a number of rollers that is a very nice fit in the space available. But nevermind that, it's off the subject a bit.

The 090's I see here are manual oilers, so maybe that's why they don't have oil pump problems! It's been a while since anybody dragged in a 3120, so I can't remember if they are auto-oilers or not, but I do know that although I have seen clutch problems on the big Huskys, (definitely operator error that time), I've not seen oiler problems. I have seen a little top handle Husky, (335 XP, I think?) that had the teeth stripped off of the oiler drive, but that one had lived a long, hard life full of abuse. I ended up replacing the crank/rod/main bearing assembly, the piston and rings, the oil pump and drive, carby diaphragms, clutch, pullstarter, etc., etc. Turned out good in the end. Nice little saw. New saws are terrifically expensive here, so the owner thought it was worth it to basically fill the cases with new bits.

Back to the 088--has anybody else out there ever melted down the oil pump drive gears and the clutch bearing cage for ANY reason?

Are the 090s of recent manufacture or old models?

 

[blsnelling]

The 084 also has an automatic oiler with a manual oiler assist, too bad the 088 didn't get the manual assist too.

Actually it's not a manual assist. The button simply allows the pump to go to full output as long as you hold the button down, reguardless of where you have it set for automatic use.

 

[carvinmark]

Actually it's not a manual assist. The button simply allows the pump to go to full output as long as you hold the button down, reguardless of where you have it set for automatic use.

Thanks, I didn't know this.

 

[rxe]

The 090's I see here are manual oilers, so maybe that's why they don't have oil pump problems!

The 090 oil pump is driven by a diaphragm that is flexed by crankcase pressure - there is a short length of tube under the carb that links up the crank case to the diaphragm. On the positive side, there are no pesky gears to set up, and it works really well. On the negative side, when the diaphragm or tube crack, you've got an air leak and you'll probably fry the piston before you notice.

On the 090, the oil pump button (manual) simply shoots a slug of oil onto the bar. Pump stroke is regulated by a bolt screwed into to the side of the oil pump - it limits the amount the diaphragm can flex, hence how much it pumps.

The 090 clutch drum is enormous! Far bigger than an 070, and it is outboard sitting in the airflow under the clutch cover. Even then it gets pretty hot very quickly if you bog the saw.

 

[tbone1911]

I had this happen to me w/my 066

The exact same thing happened to me twice w/my 066. Whenever my bar and chain cover would get really compacted and plugged up with wood shavings. It seems that the extra friction from turning the clutch rim in the shavings was enough heat to melt the cage.

 

[Lakeside53]

I've seen melted bearings in just about every manf/typesaw... it happens from time to time. Most cases can be traced back to rust (saw sat for a long time and was wet with no lube), or a foreign substance (like poly string) getting down between the bearing end and the cover washer, or simply no lube at the sprocket and no awareness and maintenance by the operator. Badly worn clutch drums rarely take out the bearings (but they will take out the oil pumps) as there is so much slop for lube etc.

It's rare. If there are multiple failures, it's for a reason.

As for bearing with no cages... consider a bearing to be a series of points that exactly space two surfaces (with a constant "gap").... If you don't keep these points the same distance apart, you'll pinch (no gap) or bias the outer surface (drum). The inner drum wears (not hardened steel), the rollers move (in bunches) , which leads wear on spots and the entire "bearing" runs eccentric". One of those bearing surfaces is the crank. Great...


Sure rollers are used in various application without cages (like an 009 crank/rod), but the entire assembly is hardened precision ground material - not soft steel as with a clutch drum.

 

[Lakeside53]

The exact same thing happened to me twice w/my 066. Whenever my bar and chain cover would get really compacted and plugged up with wood shavings. It seems that the extra friction from turning the clutch rim in the shavings was enough heat to melt the cage.

The heat came from a lack of lube that was being wicked off your chain by the packed junk. No chain lube at the sprocket = dry bearing.

When milling all day, my bearing is dry. If I'm lazy, I drip bar oil on it. Usually I'll pop it it off at the end of the day and grease it. Takes 10 seconds.

 

[JungleBiker]

Lake, tbone, RXE, thanks guys, some really good information here, not just on my 088 problem but also for future reference on 090's, which are by far the most common big saws I see here. (2dogs, I really don't know if the 090's I see here are old ones or of recent manufacture--they usually look pretty good, so I assume that they must not be too old--is it possible that Stihl is still making them for third world markets? I don't know. Until just a couple of years ago you new cars here were still coming with points ignitions and drum brakes all around, presumably because they were low-tech and more easily repaired in the bush? Certainly contact points are usually cheaper than ignition modules.) And don't worry, Lake--I have a new clutch bearing on order.

Tbone, I was really glad to hear that my 088 problem is not an isolated incident. What did you do to prevent it happening again on your 066?

 

[JungleBiker]

Lake,

This just in from the owner:

Bar length is 36 inches.
The saw is being used in an "Alaskan Saw Mill"
The wood being cut is a hard, red wood. (The locals don't seem to know what kind it is, just that it is similar to a very hard wood that is locally known as "kwila". I have heard that kwila is Pidgin for Ironwood, but I don't know if that is true--I do know that kwila is a very hard, coarse grained wood that is very light colored when green and turns to almost black when it is dry. Sometimes it has gold-colored flecks in it. Out of curiousity, can anybody tell me what this wood is called in English?)
The owner says that every time he has been there, he has observed his operators being careful to keep the oil topped up and appeared to be following proper sawmill operating procedures.

2 questions: 1.) is it possible that his bar is too short? Earlier in this thread somebody mentioned that they expected a 088 to be running a 6 foot bar. It would make sense to me that the short chain would get dull faster than a long one would, and 2.) is it possible that the wood is just too hard? My guess is that they are cutting it green--how much difference will that make? I think I've stated before that I am not a logger and not really even a chainsaw mechanic, so I'm sort of shooting in the dark here. I'm keen to learn, though, so that I can do better with this sort of thing in the future. Once again, any help is greatly appreciated.

 

[Lakeside53]

On a mill you need to remove the bearing every day and grease it. The type ofd wood youa nre cutting return very little oil to the sprocket (it has to go around the entire bar to get back.. ). You likely need an auxillary oiler mounted on the tip..

As for "dogging the clutch"...

I sharpen my chain every 25-30 linear feet of cutting 24 inch wide "soft'ish..." wood. Any more and it's a pig... and really hard to push though the wood... Yours may be worse or better... depends on the wood. A really hard wood will be worse..

Milling is hard on the saws and the sawyers..

When you get the new bearings, check the clutch drum for wobble - it may already to toast.

 

[JungleBiker]

Great stuff! What kind of auxiliary oiler do you recommend for maximum bar and chain life and which is the most user friendliest?

 

[Lakeside53]

The option available for the Alaska Mk3 mill works fine.. you need to drill a hole in the bar near the tip.

 

[hazard]

I don't have any experience fixing saw but enough experience running my alaskian mill. I gave up on drilling the hole in the bar thing. It always plugged up. Now I tie the oiler hose to the mill post and have the hose drip onto the blade. This has worked very well for me. I probably waste some oil this way but it sure beats burning up a saw.

If I have time tonight I will post a picture of the mill.

Chris

 

[JungleBiker]

Lake, Hazard, thanks for all that. I think I'll encourage the owner to look into auxiliary oiler options. Sounds like that could be a big part of the problem.

Thanks, everybody.