Stihl 064 PTO Seal

[ppxstnr]

I have a Stihl 064. It keeps blowing the seal on the Clutch side.

I figure it's either a crank that's not straight, a ruff spot on the crank, too much bearing play, or I have not installed the bearing or seal correctly.

This saw is a play toy , so it's had bearings installed several times. The current bearings are Stihl oem and are less than 6 month old. Seals too.

I did a vacuum and pressure test and the seal was leaking, no real visual signs tho. I replaced it. The saw pressure/vacuum tested good. It ran fine for about 5 mins of cutting, then went lean, wouldnt idle down.

I can do a lot of time intensive testing, but was wondering (from those with experience) what the most likely culprit could be.

Thanx

 

[mdavlee]

Sounds like the bearing has slop enough to leak or the pocket on the case is shot

 

[ppxstnr]

Thanx for the reply

 

[backhoelover]

i have seen where the seal would start spining in the crankcase. you will be able to tell when you go to install the seal. you can push it in my hand

 

[jacob j.]

I think Mike has it- the bearing pocket is shot. The early 064s were notorious for the steel sleeve that holds the clutch side bearing coming loose in the case. I've sent dozens of those case halves to the scrapper. They upgraded the case later and beefed up that steel sleeve and changed the alloy of the crankcase halves.

 

[ppxstnr]

Thanx, I'll check it. This is a newer crankcase, it has the third coil leg and required a 1300 coil for the timing to be right. My first one only had 2.
When I did the last pressure soap test the leak was dead center in the seal. Around the rubber. Didn't see any leaks at the bearing edges. Course I'm sure heat plays into it.

I'll heat the case up and test it, see if it opens up. Haven't had time to take it back apart.

Thanx for the input guys.

 

[ppxstnr]

Just found this Jacob. I assume this is what you were talking about.

 

[Al Smith]

Bearing and seal pockets : If they are wallered out one fix is to "raise" the metal by dimpling the hole with a small punch .Loctite makes some stuff called Press fit which we use at work for damaged bearing pockets on machine spindles which I have used on spun bearings .For a loose seal pocket red Loctite works well .
Now the only problem with using red is it takes heat to release the hold which is no problem if you have a good heat gun .

 

[mdavlee]

I have a 460 case that someone had dimpled all around the bearing trying to get it to stop spinning.

 

[BuckthornBonnie]

I have a 460 case that someone had dimpled all around the bearing trying to get it to stop spinning.

Did it work?

 

[BuckthornBonnie]

I think Mike has it- the bearing pocket is shot. The early 064s were notorious for the steel sleeve that holds the clutch side bearing coming loose in the case. I've sent dozens of those case halves to the scrapper. They upgraded the case later and beefed up that steel sleeve and changed the alloy of the crankcase halves.

Jacob-- you mentioned changing the alloy of the cases. I was wondering why so many 064 cases seem to crack and/or lose the bearing sleeve. Could that be the "why?"
Although I work with clapped out saws, it appears 1128s and 660s have beefier cases... especially near the case gasket. One 064 was so bad (thin, worn) that I lapped em on glass, put 518 on the gasket, and dirko on the seam (underside).

Edit- "so many" is a relative term... these saws are close to 30 and were often pro-owned... still have the ultimate respect for em.

 

[mdavlee]

Did it work?

Not at all

 

[BuckthornBonnie]

Not at all

Dang lol.

 

[ppxstnr]

Update: I re-pressure tested the saw and it passed, soapy water and all. I played around with carbs, best idle speed was about 3100. Low as it would go without making it pig rich. Also it would go rich when I rolled it on its pto side then back upright. It would richen up to the point it would die.

So, I started over. New bearing, seals, checked the crank, polished it. I'm in the process of putting it back together. I've been using the 660 style carb with the filter compensatory. I rebuilt the stock carb, and am gonna use it. Also have the two key Flywheel and I'm gonna put the 1300 coil on. I read somewhere that the Bosch coil retards the timing down low, to make it easier to start. And even tho I have more than one, those things are old-d-d.

Fingers Crossed.

 

[BuckthornBonnie]

Nice. Hopefully the complete rebuild will fix it. What intake boot/tank combo are you running?
3100 is a high idle...clutch engages around 3300 so youre close. Both of mine idle "ok" around 2500. One has a temperamental idle that sounds like it gets rich then clears up... the other is rock-steady. Both have Bing carbs and 1201a/046coil ignitions.

 

[ppxstnr]

Well it appears fixed. The tank intake Im running is stock 064. I went the 660 route once and didnt like the feel. Don't know 100% what fixed it. I installed the bearings so they would fit up against the crank shaft and have the crank centered. I also re-installed the cylinder gasket and rebuilt the stock carb (had been running a 660 carb with the filter compensator).I'm running the MMWS Cross 54mm cylinder, and don't know if that has any effect on the idle. It idles now and I have it set at 2800. In wood, it's boarder line scary.

So I guess the morale of the story IS: If you can't fix it, just replace everything. (Sort of)

Thanx for all the replies.

 

[BuckthornBonnie]

Well it appears fixed. The tank intake Im running is stock 064. I went the 660 route once and didnt like the feel. Don't know 100% what fixed it. I installed the bearings so they would fit up against the crank shaft and have the crank centered. I also re-installed the cylinder gasket and rebuilt the stock carb (had been running a 660 carb with the filter compensator).I'm running the MMWS Cross 54mm cylinder, and don't know if that has any effect on the idle. It idles now and I have it set at 2800. In wood, it's boarder line scary.

So I guess the morale of the story IS: If you can't fix it, just replace everything. (Sort of)

Thanx for all the replies.

2800 is better. Get a reading at wide open? 13000ish?

 

[ppxstnr]

Buckthornbonnie: This wekend I went back to the Tilitson, and now I can almost stop it with the idle screw if I want. That stock carb has always been hinky. I've got it set at 13,4 to 13,5, It'll still 4 stroke at 14,2 , but it has new everything, so letting it break in a little. Besides, at 13,5 it cleans up in the wood rather quickly.

I love this place, like being in a club ,( the good kind not the kind with the Kool-aid)

 

[BuckthornBonnie]

Cool. As long as it 4-strokes at wot and idles "ok," you're probably good to go.