Husqy engine failures

[micky boy]

Hi to you all,
Only found this forum recently and now wish I'd found it earlier. I see there are a lot of people who would appear to be very experienced with technical stuff, so maybe some could help with my queries.
My problems are currently over and my now saw (357xp) is running fine, but I would like to get to the bottom of my troubles.
Going back in time about 4 years I had an 044, thought this was a great saw with loads of power and great quality but the vibration was at times too much. After using a colleagues 371xp I was impressed with the vibration protection from the metal AV springs and the fast acceleration with no loss of power, so I bought my first 372xp.
I occasionaly did some carving with it in my spare time and this may have been my first pitfall ? The complete clutch assembly sheared right off the crankshaft. This was repaired under warranty after being only 2 months old ( In th U.K we only got 3 months proffesional use warranty back then). At nine months old the bottom end bearing decided to seize solid. After inspection I found it was seriously heated up and ground. So a new crankshaft and piston etc was fitted and the saw went on fine. After a while I decided to buy an MS340 as a smaller saw to work with the bigger one. I again had to change it because of vibration, but not performance. So I bought a 357xp and was well impressed. Anyway about 14 months passed and the 372xp decided to die, a chunk of piston decided to break on the outlet side, luckily it did not damage the cylinder so I took my chances and after intense cleaning inside the crankcase there appeared to be no other damage and I fitted a new piston as I was not going to fully rebuild the saw cause it was a couple of years old and would cost nearly as much as a new one.
After 2 hours use the side crank bearings seized and I parked the saw on the shelf where it remains still in bits.
Only two weeks later my 357xp lost compression and also seized. I took it apart and found that the little pin that centralises and holds the piston ring in place had come out and jammed itself in the cylinder causes serious scoring everywhere. The cost to rebuild was about 80 % of a new saw so I opted to buy another 357xp am using the knackered one as a good spare parts doner.
I was mostly using an 18" bar on the 372xp and a 15" (3/8) on the 357xp. This may seem like small bars to the cross atlantic users but is probably the norm over here. Always used fuel mixed at 40:1 as I always wanted just a bit more oil to be on the safe side- but something some where had been going wrong. I always had the saws revving to or near there limits, keep the chains sharp and service them well, as I find that you can only go as fast as your saw and the pressure is always on when cutting ahead of a mechanical harvester.
I am currently running my 357xp a bit slower at top end as a precauitionary measure incase I have contributed to the other saws deaths by revving too high.
Any suggestions
Thanks
   

[D._Frederick]

The guy's over on the arboristsite.com were discussing the problem with saws used for carving and loghouse construction. They were saying that in this use, the saw is not being run at full throttle(the engine is running at max rpm but the throttle is only half open) and the carburator will not give the correct amount of fuel which causes a lean condition.  Lack of lube causes the saw to destroy itself.

[micky boy]

Thanks for your suggestion.  I must add that I wasn't carving and hadn't carved for quite a while when the 372xp piston broke and have never carved with the 357xp's. Although I was when the clutch/crank broke (372xp). I originally suspected this breakage due to high revving with no load. The carving I was doing involved short sharp accelerations at what would appear to be max. r.p.m. From what you say the original bottom crank bearing seizure could well have been caused by a lack of lube in the mix as a result of this. It does all make sense. But the pistons still puzzle me. I suspect the pin contributed to the 372xp failure and I know that it was the cause of failure in the 357xp. But what would make the pins come out ?

I did read on here that some one mentioned too much oil in the mix (more than 50:1) and then tuning your saw to compensate with out realising you've leaned the mix. Could I have done this ??

[D._Frederick]

I would say that the pin coming out of the piston is a design flaw, some guy over at the other site showed a piston with the same problem.  They were talking about opening up the muffler to help the engine to run cooler. They(the manufacture)have added restrictions in the muffler to help meet epa standards.

[Tony_T]

What king of gasoline are you using to make mix?  Avoid anything that is an alcohol blend and NEVER use any sort of drygas in the mix.  I cooked an 028 on half a tank of mix after using gas someone had added drygas to to remove moisture from the gascan.

[micky boy]

dry gas ??   I have always used standard unleaded which is available from all gas stations over here, nothing added accept 2 stroke oil. Up until about 5/6 years ago we always used leaded gas with our saws, some said that they ran cooler than unleaded. One thing I have just remembered which may or not bare any resemblance is that two days before the 357xp's piston seized I did use one tank full of mixed fuel of another workers as I ran out and it was easier to use his than go back to my van to top up. His 2 stroke oil was mixed at 50:1 but it wasn't specialised chainsaw oil (Stihl/Husqy,I do use stihl), and I do recall that Husqy and Stihl quote in their manuels to mix any other 2 stroke oils at 25:1. Could this one tank full have been enough to cause damage and let the saw run for two days. But I still don't understand what would make the pin come out. Heat, speed, vibration  

[twistedtree]

Could you be running the saws too lean?  Husky's have a great reliability record along with Stihl, and it sure seems odd that you've had so much trouble.

[Rocky_J]

dry gas ??   I have always used standard unleaded which is available from all gas stations over here, nothing added accept 2 stroke oil. Up until about 5/6 years ago we always used leaded gas with our saws, some said that they ran cooler than unleaded. One thing I have just remembered which may or not bare any resemblance is that two days before the 357xp's piston seized I did use one tank full of mixed fuel of another workers as I ran out and it was easier to use his than go back to my van to top up. His 2 stroke oil was mixed at 50:1 but it wasn't specialised chainsaw oil (Stihl/Husqy,I do use stihl), and I do recall that Husqy and Stihl quote in their manuels to mix any other 2 stroke oils at 25:1. Could this one tank full have been enough to cause damage and let the saw run for two days. But I still don't understand what would make the pin come out. Heat, speed, vibration  

Unfortunately, many people out there end up graduating from high school without the skills necessary to comprehend mixing two cycle fuel properly. I'm sure he thought his fuel was 50-1, but who's to say? I learned many many years ago to never trust anybody else's fuel. Nothing personal, but I can't afford to take the chance. I've always mixed my fuel just a tad rich (40 or 45-1), just enough to satisfy myself that there is no chance of the mix being too lean.

The line you're quoting about mixing other brands at 25-1 is unadulterated bull manure. Some unscrupulous dealers might try to feed you this line in order to sell you a particular brand of oil, but it's crap. This is an oversimplified way for Stihl and Husky to coerce idiots to use quality oil instead of Joe's Hardware brand two cycle oil. Running any two cycle oil at 25-1 will make any saw choke out from too much oil.
Just use a premium two cycle oil (specified for air cooled, NOT marine oil!) mixed at the proper ratio and you can run it in virtually any modern small two cycle air cooled motor. When you go to your local servicing dealer and look in the shop, just how many different blends of two cycle fuel do you think they have for the 20-30 different brands of two cycle motors they sell or repair? They have ONE big can of two cycle mix, a premium oil mixed at 50-1 or a little richer.

[Lewis Brander]

Have you kept your carb properly adjusted? Saws from the dealer should have been properly adjusted, but the fact remains that after you run say 8-10 tank of gas through you saw it will be running lean, gaining RPM's and the carb should be readjusted. On another site there was a posting in a thread about Shihl and Husky changing the fuel mix ratios. The owner's manuel may say 50/1, but they were saying this, if I recall correctly: On the smaller saw run 40/1 ratios. On midsized saws up to 7 cubes run 32/1 and over 7 cubes run 24/1. Apparently this was in relation to the piston/crankshaft and brg failure problem the dealers were seeing. More oil less failure. But most problems were caused from carbs not adjusted properly after breakin. Saws running too lean, especially under a no load condition where the sws could really rev up. Just thought I'd throw this in here for you to see, take into considertion and comment on if you want. Take care. Lewis Brander 

[micky boy]

Thanks to the  recent comments and suggestions. I must say that I do agree with all that you say and am appreciative of anything, as we can never know enough and just when you think you know it all something puts you back into line. .  I would argue till I was blue in the face that there is always enough oil in my mix, cause just like most others I ad that little bit more to be sure but the trend in comments is leading to comfirm my suspicions that my saws are running too lean. I am not looking to blame someone else or even manufacturing faults for my troubles and am aware that I may be running my saws too fast but it is just nice to here other peoples opinions on the subject so I can improve my knowledge. I will certainly not be running my saws at the full rpm's for the time being and make double sure that they are correctly adjusted, although they always start well, tick over and accelerate well. I change the plugs and fuel filter every couple months and clean the air filter every couple days or so. I think I will take my 357 back to the dealer to be set on the meter.
Thanks again.
Any other comments then please post.

[macpower]

Just want to make a comment here. Out of all the saws that we have come in with "toasted" engines, top and/or bottom end failures, 8 out of 10 will have some water in the fuel tank. The other 2 will have a crank seal gone, or just no oil, or some other problem. We very seldom find any "defects". Yes we have had the occasional crank failure or wrist pin retainer or  broken ring, but it is not common.
How often do you guys clean out your gas cans, or dump out and clean the fuel tanks on your saws? The fuel filters will not stop water.

[micky boy]

Just had my 357 tuned by my dealer cause I have been running it rich and after the recent comments/questions I thought I would get it set on the tachometer. I gave him the saw and he took it out back, when he brought it back I asked what it was now set to, he replied with his finger pointing to his ear. As I trust that they should no best I was happy with that, he just said that he opened the saw up a bit. At home I did check to see what the H screw was set at and it was between 1/2 and 3/4 of a turn ( say about 7 o'clock on a clock face). The saw is revving higher now than it was and sounds nice, it doesn't sound too fast when cutting through but on limbing (softwood mostly)or smaller trees it does sound  a bit fast cause the saw aint under full load. Please correct me if I'm wrong but shouldn't the high screw be turned out closer to 1 turn or just under. I have never had a H screw turned less than 80% open. The saw is about three months old now, on an 18" bar, .325 chain.

[Kevin]

1 turn out for that saw, you might consider getting your own tach.

[micky boy]

Yeh, I think I will.
Gonna have a look later

[Kevin]

Remember to clean the air filter prior to making any adjustments.

Did your dealer check the air filter before setting the carb?

[micky boy]

I cleaned the filter myself just before I took it in and it had a new plug. But I heard him blowing it out with the compressor anyway.