440 044 rod bearing ? for Stihl Men

[Justsaws]

I picked up another 440 with a bad rod bearing. I am wondering how common this is for this series? Not looking for a bash Stihl or 440 thread. I have two with bad rod bearings. The piston and cylinder sets are fine. The bearing cage seems to crack and separate. I am guessing that I would need to replace the whole crank. Just looking for information and opinions on what causes it to happen.

Got a small load of saws today and I am sorting them out. A great way to spend a raining day.

 

[rupedoggy]

Just looking for information and opinions on what causes it to happen.

Low octane fuel causing pinging (not always audible) beating out the bearing.
Lugging the saw down and causing bucking and chattering of the engine.
Not enough oil in the mix.
Water got into the crankcase at one time.
Defective bearing from the factory.
Dirt or foreign substance got into the crankcase.
Just worn out.
Somebody did the rope trick for changing the clutch and broke the bearing/cage.
Low rakers causing the saw crankshaft to jump and buck.
Repeated application of the chain brake with the saw running fast.
Broken fins on flywheel or other imbalance problems.
Connecting rod rubbing on crankshaft cheek causing metal particles to get into bearing. This is usually a result of not centering the crankshaft after a rebuild.

 

[tek9tim]

Somebody did the rope trick for changing the clutch and broke the bearing/cage.

And how's that different (to the rod bearing) from using the genuine Stihl piston stop?

Didn't mention keeping it at high revs (like no-load WOT) for prolonged periods, but that's a pert dern good list.

 

[rupedoggy]

I don't feel there is a difference in using the piston stop. The problem comes if you strike the wrench or tool for loosening the clutch. Sorry I was not clear on that. Steady pressure is the correct way to loosen. Having said that, I still use a 1/2 inch air impact gun. I confess to breaking two 125 Mcculloch cranks. I have not had trouble in a couple hundred others. I do not block the piston so compression is my only counterforce to loosen, (that and inertia). Mike

 

[Justsaws]

Steady pressure is the correct way to loosen. Having said that, I still use a 1/2 inch air impact gun. I confess to breaking two 125 Mcculloch cranks. I have not had trouble in a couple hundred others. I do not block the piston so compression is my only counterforce to loosen, (that and inertia). Mike

That is the same way I usually remove a clutch on the large saws.

The saws in question came from two different dealers in two different areas of Ohio. I have done nothing to them other than pop the cylinders off. I have seen a couple of other 440s with the same problem. For the number of 066s and 064s I see and/or get to work on I have not seen one with a bad rod to crank bearing. Every other bearing, yes. I guess I was wondering if other people are seeing this problem. I have got a couple nice cylinder sets and nothing to put them on. The saws have no other damage. They do not appear to have been overheated or even run hard. Back to the pile with me. Thanks.

 

[Lakeside53]

By "rod" bearing were talking about non-replaceable crankshaft to rod bearing, not the small end bearing that is supporting the piston pin...?

I've seen it on the BR400/420 series (there was a partial recall), but never on a 044/440. I've seen plenty of "worn out" bearings/rods, where the side to side play become just to much, but not a broken cage.

How many hours did these saws have on them?

I doubt the method of removing the piston has much effect on this.

 

[Justsaws]

Lakeside, I do not know how many hours were on the saws. The two I own I bought in lots of saws. One of them(044) looks well used and crank/rod bearing cage is cracked. The piston and cylinder are usable. The other one(440) looks barely used and the crank/rod bearing is also cracked and falling apart. The piston and cylinder are great, look barely used at all. The other saws that I looked at recently with bad bearings were used but not abused looking. The rear handle on almost half of them was cracked, but that is a different posting. I guess I was wondering if there was a problem early on that had been resolved or if there was something being done to these saws that was causing this failure. Looking for something saw type specific as I rarely see bad c/r bearings on other Stihl saws that cannot be attributed to wear or error. I will keep looking for a good crank setup. I would like to build up one of these saws.

I see more of these saws than I do 046/460s for sale. I would like to find one of these as well but very rarely see one in need of a repair that puts it in my price range.

If I find out any more detail after full tear down I will post it. Thanks.

 

[Lakeside53]

I'll check with my Stihl technical contact and see if the same problem in the BR420 cranks ever made it into any of the 044's.


Many of the ex-logging industry 044's out here are just junk. They have had multiple top end rebuilds and sometime even lower rebuilds, but are plain worn out. They also have a few thousand hours on them! Buyer beware - particularly Ebay.

 

[Justsaws]

I'll check with my Stihl technical contact and see if the same problem in the BR420 cranks ever made it into any of the 044's.


Many of the ex-logging industry 044's out here are just junk.

Thanks for looking into it. There is quite a bit of logging around here but their saws crankcases, piston and cylinders usually do not look so clean and crack free by the time I get them. Road hard, put away wet and sore would be how I would describe the logging saws.

I will keep looking for one to rebuild and call my very own.

 

[Lakeside53]

I did some checking and yes, there was a problem... The cranks were updated a couple of times, the last being around the time of the MS440 introduction. You can identify the cranks more likely to fail by the lack of oil notches on the rod. The bearing was also changed.

The failures were sporadic and seemed to be more prevalent in areas that used short bars. The "short bar-ing" without paying attention to WOT (max rpm) was suspected as being the primary cause of failures. i.e over reving.

 

[klickitatsacket]

I have seen several broken cages on the large end of the rod. Usually you will see signs that low octane fuel was used. I could be wrong, but I would say that most of the time that when the large end is busted it is due to pre-ignition. If you see signs of excessive heat on the rod then I would lean more toward the lubrication or contamination causes.

 

[Justsaws]

I did some checking and yes, there was a problem... The cranks were updated a couple of times, the last being around the time of the MS440 introduction. You can identify the cranks more likely to fail by the lack of oil notches on the rod. The bearing was also changed.

The failures were sporadic and seemed to be more prevalent in areas that used short bars. The "short bar-ing" without paying attention to WOT (max rpm) was suspected as being the primary cause of failures. i.e over reving.

Lakeside53, thanks again for looking into this. The ones I am looking at do not have oil notches. I would not have asked but it was odd given the lack of heat stress and overall great condition of the rest of the crank and other bearings. Also given the number of saws. I would feel safe guessing by the bar collection that came with this group of saws that they were running 16" and 20" 3/8 setups. I would also feel safe in saying that few around here pay much attention to the WOT rpms at all.

Are there any other saws that share the same crank? Cut-off or chainsaw?

 

[Justsaws]

I have seen several broken cages on the large end of the rod. Usually you will see signs that low octane fuel was used. I could be wrong, but I would say that most of the time that when the large end is busted it is due to pre-ignition. If you see signs of excessive heat on the rod then I would lean more toward the lubrication or contamination causes.

Klickitatsacket, I have also seen many crank/rod bearings but they usually had other obvious signs of failure. These saws were puzzling given the overall great condition of the rest of the components. I would usually assign blame for failure on the operator or mechanic error but these saws struck me as different. I am not saying that all the failures in question are solely due to design but rather a combination of design and an operator error that normally might not have been as big an issue. Many smaller issues amounting in failure. Thank for the reply.

 

[mini kahuna]

just had the same thing happen to an 019t,small piece of lower con rod bearing cage "chipped away" and ruined the piston,jug.
I believe the damage was caused by low octane fuel also.
pre ignition,something gotta give.

 

[Lakeside53]

Lakeside53, thanks again for looking into this. The ones I am looking at do not have oil notches. I would not have asked but it was odd given the lack of heat stress and overall great condition of the rest of the crank and other bearings. Also given the number of saws. I would feel safe guessing by the bar collection that came with this group of saws that they were running 16" and 20" 3/8 setups. I would also feel safe in saying that few around here pay much attention to the WOT rpms at all.

Are there any other saws that share the same crank? Cut-off or chainsaw?

The 044/440 crank is only used by that series saws.

I agree with the prior post that says failure is often a combination of events... Continued shocking (not just the pre-combustion type) by high-rev/lug/high rev/lug was also suspected. Amazing how well a 044 will cut with a blunt chain and a 16 inch bar if you just keep jambing it into the wood!

 

[Justsaws]

Thanks for the crank info, to bad as I was hoping for more alternatives. As for grinding through a log with a short bar and dull chain, I see that more often than not. I just do not get it, sharpen the dxxx chain. It is a though people are allergic to files. It would drive me nuts to have to deal with a dull chain in the wood. Short baring is a error that I love to make but I re-adjust for engine concerns. I have not had any problems so far but I am careful about the RPMs. I am enjoying my Stihl collection and will eventually add a 044 to it, if I find enough cranks more than one.:biggrinbounce2: