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How can you tell if your Stihl crankshaft bearings are shot?

Started by Andy171361, December 08, 2015, 04:45:41 AM

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Andy171361

I am rebuilding a Stihl 044.  I bought it as a non runner with a scored piston, as a restoration project.  I have had it running but I was not fully confident in it and, as it is a 10mm wrist pin model on its original Stihl cylinder, I do not want to trash it. I have now completely dismantled it.  When I first got the clutch side crank bearing off there was no doubt that there was some dirt in it.  I have spent quite a while flushing it with detergent and flushing it under running water.  I am pretty sure that any dirt that is going to come out has come out by now.



The question is how can I tell if I need to replace it?

In running water it spins really well but when I have dried it out if I stick my finger in the middle and spin it I can feel a slight bit of resistance.  I sprayed a little light oil on it and left it overnight and now I can hardly feel any resistance.  Last night I was all set to order a new bearing but now I am not so sure.  Do I replace this bearing or not?

bill m

You have gone this far so why not just replace them. Not much money for the peace of mind knowing that they are good.
NH tc55da Metavic 4x4 trailer Stihl and Husky saws

Andy171361

That's a fair point!  And, if I am honest with myself, I think you are probably right

One slight problem I have, though, is that the clutch side bearing came off the crankshaft nice and easily whereas the flywheel side one is being obstinate, to say the least.  I have tried putting the crankshaft in the freezer for several hours, as suggested elsewhere on Forestry Forum but, even after a cold soak like that, a sharp tap does not get the flywheel side bearing off.  I would be more inclined to replace both bearings than just one but, at the moment, I'm a bit stumped.

I suppose I should have started a thread on how to remove the flywheel side bearing.  Any suggestions?

HolmenTree

When you split the crankcase your supposed to tap on the flywheel side stub of the crankshaft with a soft tipped hammer to split the crankcase halves apart. The 2 main bearings stay in the crankcase halves, then you press the bearings out of the halves after the crankshaft is removed and when your able to lay the 2 halves flat on the bench.
It looks like you heated the crankcase and after you split it apart the bearings stuck to the crank.
You will have to get a bearing separator tool to make enough clearance between the bearing and crankshaft so you can pull the bearing off with a gear puller.
A thin chisel can spread the bearing away from the crank but you'll still need a gear puller.
Making a living with a saw since age 16.

Andy171361

 Hello Willard, it is good to hear from you.

Actually I did not heat the crankcase but used two modified G clamps and a small piece of angle iron to serve as a crankcase splitting tool.



 

It worked when I rebuilt my 038 Magnum last March, (as you can see from the picture)  but that time both bearings stayed in their pockets.  This time one bearing stayed in its pocket and the other stayed on the crankshaft.  But you have given me an idea!  If I heat the flywheel side crank case and freeze the crank and bearing I could replace the bearing back in its pocket and try tapping it out as you suggested.

I'll let you know how I get on...


HolmenTree

Good to hear from you again too Andy!
No I wouldn't reassemble and try what I suggested, just try and borrow a gear puller and pull the bearing off the crank.
Install new bearings and seals and if you're replacing the piston and rings you'll get a new pin clips and top bearing too.
Make sure you have the 2 centering pins in the one crankcase halve sticking about 1 mm above surface to hold the crankcase gasket in place. A little grease on both sides of the gasket and reassemble.

I have a 1989 044 10mm waiting to get totally rebuilt, might not get done this winter though.
Making a living with a saw since age 16.

Andy171361

Hi again Willard. 

Too Late! 

I am pleased to report that freezing and heating to reinstall the bearing worked.  I tried tapping the end of the crank shaft but as the taps got bigger and the hammers got heavier I eventually realised I should use my clamps instead.  I simply made sure that this time the tips of the clamps were on the bearing outer race so that when I screwed the clamps in the bearing stayed put and the crankshaft came out. Next I pressed the bearing out, again using my clamps and a small socket.  So now the crankcase halves are in the dishwasher while my wife is away.  I will order the parts and look forward to rebuilding it.

Incidentally now that I can examine both bearings closely I can see with a 10x magnifier that the surface of the balls is pitted and crazed so I feel better now about splashing out on new ones.  When I first got this saw running I cut one tree down with it but I felt that it vibrated more than my 038 Mag.  Now I know why.  I'll post a photo of the finished article when the rebuild is complete.

Cheers

Andy

PS  Bill M you were right, of course.  Thank you for your wise words.


celliott

Anytime I have a crankcase split, I just replace the bearings anyways, regardless of how good they are (although I usually do husqvarna's with standard size affordable bearings  ;) )

But like Bill said, you've gone that far, you're already in it for new gaskets and seals, might as well do both bearings. Peace of mind.
Chris Elliott

Clark 666C cable skidder
Husqvarna and Jonsered pro saws
265rx clearing saw
Professional maple tubing installer and maple sugaring worker, part time logger

joe_indi

To check if your bearings still have any life in them try this: Mix some fuel and two stroke oil @ 3:1. An ounce should do.Place a bearing flat in a small container and pour the mix over it. Rotate the bearing in the mix. Tap it on a tissue and soak it again. Repeat the tap and soak. After a couple of times, do a final tap, slide it on to a finger and spin it. It should spin very smoothly without any gritty feel. It should spin for a very short time maybe a rotation or too, held back by an oily stickiness like resistance. If it doe that it is good for some more time. If it barely does it, it is still good, but for a shorter time, but might be a bit noisy.

Texas-Jim

I always replace them if i go to the trouble of tearing it down. They are about ten buck each but still very worth the peace of mind. They are differant so dont try use same one for both sides. If you need part numbers

left side-9503 003 0346
right side- 9523 003 4275
What we do in life echoes through eternity.

Al_Smith

You actually do it both ways . Bearings in the case halves or on the crankshaft .Depends which method you prefer .

The way I disassemble them is with a heat gun on the bearing pocket that just tap them out one half at a time .

Usually a night in the deep freeze gets the bearings off .I've had some it took several trips to the freezer .To get them back on a little heat from the heat gun on the bearing and onto a frozen shaft then the whole thing back in the freezer .Then heat up one bearing pocket, pop it on then the next before the bearings warm up .Works for me .

Andy171361

Thank you for all your recent replies, which are all much appreciated:

Chris and Texas Jim - I know you are right about replacing the bearings being the logical way forward (and thanks for the part number) but they are a lot more expensive in the UK than in the 'States.  The cost of the two bearings here is £33 which is approx $50 US.  If I can re-use the old ones then I must at least consider doing so.

Joe- I like your fuel/oil bearing test.  I tried this and have come to the conclusion that it is probably worth using new bearings. (Despite the high cost in the UK!)

Al - I referenced your freezer method in one of my earlier posts and I used it successfully when I rebuilt my 038 Mag last March.  Also when I replaced the crank, plus flywheel side bearing, a couple of days ago before successfully getting the crank out of the case while leaving the bearing in it.  The Stihl 034 service manual even gives a temperature for the oven (150*C if I recall) plus the advice to re-fit the oil pump (but first remove the plastic plug!!) before heating the clutch side crankcase half.

And yes I did say 034 service manual and yes we are talking about a 044 saw.  I have managed to download service manuals for free for: 034, 038 and 039 but I have not managed to track down one for a 044, without having to pay for it.  If anybody could point me in the right direction that would be great!

As ever I am very grateful for all the collective wisdom and experience that you can find on this website. 

Thank you all.

Andy

Andy171361

Here is the conclusion to the bearing quandary...

After considering all the helpful advice I received I ended up going for new bearings plus oil seals, and while the saw was in pieces I replaced the oil feed, impulse line and fuel feed lines too.  I kept the original OEM cylinder but fitted a new Meteor piston.  Fitting the new bearings was easy using the freeze the bearings/heat the crank technique (thank you Al Smith) and likewise mating the two crankshaft halves was easy using the tap and screw technique (thank you Joe Indi).

I am running it with a 1:25 mix until the new piston rings have bedded in.  I cut a load of logs with it yesterday and I am pleased to report that it starts easily, idles nicely (a bit on the high side once warm, but I will retune that in due course) and pulls well.  Actually it pulls VERY well so I am pleased with the end result.

Thanks again for your contributions and a Happy New Year.

Andy

pwheel

Quote from: Andy171361 on January 12, 2016, 04:05:54 AM
Here is the conclusion to the bearing quandary...I am running it with a 1:25 mix until the new piston rings have bedded in...
I would defer to more experienced builders, but I'd be concerned about carbon build-up and would tend towards a 1:40 mix instead. Fine job with your project; I especially like the G-clamp case splitter. :-)
Stihl MS260 Pro, MS261, MS440 x2, MS460, FS90; 1982 Power King 1614

Andy171361

Ah yes, the age old "what is the best oil:fuel mix ratio?" debate! 

Basically I opted for a tank full of 1:25 mix because I had  some mixed up for milling. I have read all sorts of recommendations for mixes on this (and other websites) including 1:25, 1:32, 1:40 and 1:50.  Of course Mr Stihl's standard recommendation is 1:50 (so long as you are using Stihl 2 stroke oil, but 1:25 if you are not) which I use for normal felling and logging.  But I stumbled over a reference somewhere suggesting a 1:25 mix for milling and gave it a go.  So far the saw (an MS 660) has worked fine using this mix and as I had some made up I decided to use it.  I will certainly use 1:50 for subsequent tanks.

Thank you for your kind words - a bit of encouragement is always appreciated.

celliott

Nicely done!
New bearings, seals, impulse, oil and fuel line, that saw will be good to go for a long time!
Meteor piston in the OEM cylinder is exactly what I would have done myself. I think I have more saws running meteor pistons than OEM, but all OEM cylinders.

I run 32:1 mix. Why? Just because  ;D It mixes easy with my size gas cans.
Chris Elliott

Clark 666C cable skidder
Husqvarna and Jonsered pro saws
265rx clearing saw
Professional maple tubing installer and maple sugaring worker, part time logger

Ada Shaker

A bit late but glad to see you decided to replace the old bearings for new ones. Placing things in the freezer works well at times as does putting them in an oil bath and heating them somewhat.... I don't generally take the temperature passed 125C as it can affect annealing but it depends on what your cooking. Old (spent) engine oil works great and gives it a second lease of life for such things. Submerging in heated oil expands the aluminium case in its entirety rather than locally which may have an adverse effect of compressing itself around a bearing as it tries to expend. I've had bearings just fall off as I've pulled them out of the bath as the expansion rate of aluminium is far greater than that used in steel bearings. I've also carefully and methodically heated the inner race of a bearing with the tip of a naked flame to remove the bearing.

On a different note I spoke to one of the sthil tecky guys around here on oil/fuel ratios a short while ago. The general consensus was that a fuel ratio of 50:1 was more than adequate, he claimed that sthil had tested their saws at 100:1 with no ill effect on the saws, but the engineers had decided to recommend 50:1, as not all loggers passed maths back in the good old days...... Also decreasing the oil/fuel ratio had no real ill effect on the saws other than blowing a bit of extra smoke and clogging up the spark arrestor prematurely, which makes sense to this boy... Just don't take it down too low like 1:1 or some ridiculous figure like that.
If it hangs to the left, your likely to be a Husqvarna man.
If it hangs to the right, your likely to be a Stihl man.
Anything else is an uncomfortable compromise.
                             AND
Walking with one foot on either side of a barbed wire fence can become extremely uncomfortable at times.

Andy171361

Hello Chris and Ada Shaker

Yes, I am glad I replaced the bearings too and hopefully the saw will last a long time with all the new parts on it.

Thanks for your further hints about heating in oil baths, I will bear that suggestion in mind for the next time I and rebuilding a chain saw.

MIXES!!!  I  have looked through a lot of threads and postings on this website and I am astonished how much passion this subject creates.  I think I will leave this subject for people who know something about it because I certainly would not claim to!

Cheers

Andy


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