Stihl 066 oil seals

[cleargrain]

Howdy,

Just had the oil seals replaced on my 066.  The one on the flywheel/pullstart side had failed.
Used half a tank to fell and buck a 24 inch doug fir and the saw sounds like it needs to go back to the shop with the same symptoms it had before they replace the seals - over reving at idle, and a light tapping noise at higher rpm under load.
Any ideas?

-Scott

[windthrown]

Make sure that your carb and muffler is tight, and there are no air leaks in your filter. Also check/replace the impulse line. Leaks in the impulse line can cause all kinds of problems. Also do a WOT wood cut for a minute and shut the saw off, and pull it to check the plug color. If it is white, you still have an air leak (or the carb H screw is set too lean or you have a clog in the fule line someplace).

Funny idle can also be a bad L set carb. Use a tach, and set the idle at 3300 RPM, then turn the L screw either way. Set it to the highest revs that you find. Then reset the idle to 3300 again, and tweek the L screw again until you find the higest idle speed. Then throttle it to check the response. Lower the idle until the chin stops spinning. Then reset the H screw; at WOT out of the wood, it should 4-stroke/burple. If you do not have a Red Light model like I had, the RPM should be set to 13.5k. If the carb will not set right or it still runs funny, try rebuilding the carb. One of the diaphrams may be shot, or there may be a gasket leak or clogged jet.

Lastly, if your 066 goes out like mine did, the bearings are shot and the crank is moving around, causing the seals to leak. My chain side bearing went and took the seal out with it. Check for bearing loosness by pulling the B&C and clutch drum, clutch and oil pump/drive gear, and the starter. Try to move the flywheel and clutch diagonally and see if there is any play in the crank. If there is any play, the bearings are fried. My 066 ran pretty good even with fried bearings. Finally the loose bearings took out the oil pump gear and that was it. It is a PITA to replace bearings on an 066. I parted mine out rather than try to fix it.

[Al_Smith]

   It is a PITA to replace bearings on an 066. I parted mine out rather than try to fix it.

Well a lot of people say that but I'm not one . ;)

[windthrown]

   It is a PITA to replace bearings on an 066. I parted mine out rather than try to fix it.

Well a lot of people say that but I'm not one . ;)

Yah, well after getting up off the floor after hearing the quote for the price of the new bearings and seals, I decided to part out my Red Light 066. I got more out of the parts than I could have gotten for it working with the new bearings. Also if you have all the gadgetry required to split cases, good for you. Most of us don't. I cooked one case in the oven, and I said to myself, 'What am I doing? Cooking a chainsaw?' No more case splitting and bearing replacement for me, thanks. Keep the chains looser and save your bearings. I have a blown bearing 026 case as well... and the bearings to put in it. In the shop it will sit... probably forever.

[Al_Smith]

Oh if you had a shop split the cases it would cost a bloody fortune .

The case splitting tools would be nice I agree but not a total neccessity .

There are other methods which work just as well although not as quickly .

Fact is as I type I have an 038 mag sitting on my bench which is getting a case change because of a hole in the oil compartment .Were I able to post pictures of the proceedure I would but really it's rather simple to do . All you need is a heavy duty hair dryer or industrial  heat gun and a deep freeze .Freeze the bearing ,heat the case ,they pop right in --after a little persuasion .

Seals are really easy .Use a drywall screw to pull out the old and a deep wall socket to press in the new .

[cleargrain]

Windthrown,

Thanks for the advice - esp about the WOT cut and plug check.  Easiest way I've heard to check for an air leak.   If the bearings are shot, does the chainside oil seal tend to fail first?

I'll give it work over this evening.  Also didn't realize it might be worth more as parts.

-Scott

[windthrown]

Well, the spark plug can tell you if you are running lean... or rich, or oil fouling using TCW outboard motor premix oil. Lean can be from air leaks, a clogged fuel line someplace, or the H jet is set too far into the carb. A well set carb with no leaks will result in a chocolate brown plug in a 2-stroke saw.

I do not know if the seals on one side or other typically fails faster. I have found that the sprocket side bearings tend to fail first, at least in all the saws I have bought with blown case bearings or bought used that had bearings fail, anyway. The sprocket side bearings fail becasue its the side that has variable tension due to the chain tightness. People commonly over-tighten chains on saws. Or they tighten the chains when they are hot, and they cool and shrink and pull hard on the bearings. Many guys completely over-tighten the bar nuts as well. They need to be tight, but not gorilla tight. I learned a trick to tighten chains from an old school knuckle dragger logger. Lift the bar up when it is loose, and tighten the chain just until the outer chain links contact the lower bar rails. In the case of some Stihls, you want to tighten the chain so it sags just a tad, and when you tighten the bar nuts, it takes up the slack and the chain contacts the lower bar rails. I have never blown a bearing in a saw that I bought new. Also if you tighten the chain when the saw is hot, loosen it before the saw cools off.

Yah, I got a lot for my 066 in parts, and I still have the coil and 32" bar and chain from it in really good chape. The engines and back handles are worth a lot, as well as the 3/4 wrap, carb, starter and DP muffler that I had on it. I even sold the blown bearing case for $30. I would have liked to have kept that early Red Light 066 model running, but it was not to be. Just too expensive and hard to fix. The 066 is a good saw. I do a lot of top end and port mods, but bearings are a limit for me. It would be nice to have the professional fancy Stihl case pullers, then it would be a snap to change out bearings. Without them, its too hard.   

[Al_Smith]

It takes me around 3 to 4 hours total to do a case split and rebuild .That includes disassembley,clean up and the heating and freezing cycles involved to install the case bearings .Were that done in the shop I use for parts it would have been billed at $59 per hour . In addition most lkely the bearings seals and new gaskets could add up to $100 or  more I imagine . Toss in a new cylinder and piston and it amounts to about half the cost of a new saw .

I would also imagine they might use a flat rate book for various repairs rather than hourly rate charges .

So the morel of that story is it might not be a bad idea if a person were really interested in saws to learn to do these repairs themselves . Then again not everyone thinks the way I do . 8)

[cleargrain]

Thanks for all the advice.   
Stripped the saw down and found that the lower bearing were shot. 
Guess I'll be parting it out and looking for a new saw.

-Scott

[windthrown]

In addition most lkely the bearings seals and new gaskets could add up to $100 or  more I imagine . Toss in a new cylinder and piston and it amounts to about half the cost of a new saw .

OEM 066 right and left bearings alone are $95 at Baileys (plus shipping). 066 gasket set with crank seals is another $65 from Baileys. With shipping the bearings and seals and gaskets are $165. OEM cylinder assembly is another $350. So OEM parts alone are well over $500... the price of a running used 066 around here, or a tad less than half the price of a new one.

I sold the parts off my 066 for over $300. I can buy a ~really~ nice condition used 066 for about $700, and I have a 32 inch bar and chain for it... and a spare coil from the donor saw. And a $100 bill in my pocket, and no having to split, bake or freeze cases. Low end work is just not economical for me, even if I did it myself.

Similar to my 026: I got a good lower used case to replace my bad bearing 026 case. It was way cheaper than a new bearings, let alone the seals, gaskets and time.

[Al_Smith]

 I figuered it would be about half new replacement  cost ,about par for the course .

Because of the costs involved I've been on the other end of the spectrum and have found so really good deals .As they say one mans poison is another mans meat . 8)