Husky 385 is fried.

[John from Cle Elum]

Hi

I was milling a 24" doug fir using a 385xp on a pather mill. It was my first try milling. I was runnning great until about 5 boards into it when it abruptly quit. Not enough compression for restart. I rebuilt the thing about 10-15hours ago. New bottom end bearings, rebuilt carb, new Meteor piston and reused the cylinder. I was very careful about keeping things clean on reassembly. It was running great.

Tore it down and the piston was scarred a little on the top near the exhaust port and the piston side was deeply scored at the exhaust port. The cylinder is scuffed pretty bad but not scored. It may be just metal transfer. It might be ok. It looked like some debris found it way down the side of the piston. There was some hard non-metalic stuff on top of the piston. It looked like that, or something, else got between the cylinder and the piston. Very little carbon on the cylinder head or piston top. Questions:

Does anyone have an idea on the source of the junk? Where should I look. I am thinking it might be a bearing retainer or something. Could it have been carbon from the muffler or junk from the muffler that got there during transport.

Is there an aftermarket piston/cylinder that is worth the bother of installing. I probably don't want to go factory parts because of the expense and the conditon of the saw. I might try an after market if any one has had good experience with a particular manufacturer.

I will post some pictures later if I can get some good ones.

Thanks
John

 

[HuskStihl]

 

[ft. churchill]

Check to see if all of the circlips are on the ends of the piston pin as sometimes the ends of the circlips will break off at the bend..... ask me how I know.

 

[HuskStihl]

Check to see if all of the circlips are on the ends of the piston pin as sometimes the ends of the circlips will break off at the bend..... ask me how I know.

That's why I will always use OEM circlips, and throw away the ones that come with the AM piston

 

[nitehawk55]

And have the open ends of the clips pointed up or down....never to the side .

 

[John from Cle Elum]

I just had another look at it and pulled the piston off the connecting rod. I had to tap the pin out. The clips were ok but the wrist pin bearing was trashed. Needles fell out when the wrist pin was removed. Retainers were in many pieces. I am pretty sure that's were the junk in the combustion chamber came from. I am not sure I got all the needle bearings. I only found 9. Oh well, I will have to flush the bottom end big time.

 

[bag-o-donuts]

Well, at least it's no longer a mystery. Mechanical mysteries suck.

 

[redfin]

Curious what oil and ratio and fuel you were running?

 

[Chris_In_VT]

Did you reuse the wrist pin bearing or was it new? OEM or AM?
Give everything a liberal coating in 2T oil on reassembly?

That sucks...

 

[blsnelling]

My guess, melted aluminum on top the piston.

 

[Mattyo]

Ie...he was asking too much of the saw?

 

[blsnelling]

Did you richen it up past the factory limiter settings? If not, that's likely the problem. You also need to be using more oil than 50:1 in a milling application.

 

[John from Cle Elum]

I was using a little more oil than 50 to 1. One bottle of Stihl Ultra to a little less than a gal of ethanol free gas. The crank case had a lot of oil in it but I will go to 40-1 just to be sure. Since it was a recent rebuild, the mixture was set at factory (1-1/2 turns if I remember) which is actually a little rich since it happened at about 3500ft alt. It sounded ok at WOT. The top of the piston looked ok except for the impact damage. It was a new aftermarket bearing, but I am not sure where in China it was made. Question of the day: Was I asking too much of the saw? It is a pretty powerful saw. This was real nice straight piece of dense doug fir. Definitely structural select if it was graded. I really didn't know what to expect.

I looked at the cylinder and it will clean up ok. I plan on using a factory bearing and another Meteor piston. Chalk it up to bad luck with an aftermarket part.

Pictures below. The dark side is the exhaust side. Most of dings on the top are on the exhaust side. The size of the big score marks on the sides of the piston are about the width of the bearing cage fragments.

 

[Chris_In_VT]

I don't think milling with a 24" mill is asking too much of a 385xp if it's tuned right and you have a good chain. Didn't logosol used to sell a mill with the 385 as a powerhead?

Why did you rebuild it in the first place? Did you ID the reason it burned down before?

 

[blsnelling]

Saws aren't tuned by a certain number of turns out. That is simply a starting point. A factory stock saw is tuned with a tach to a given RPM. For milling, it needs to be tuned significantly richer than that, tuning it by ear so that it just barely cleans up under load.

You should be running 32:1 oil ratio for milling purposes especially. Milling is the hardest work you can do with a saw. Additionally, the 385 is one of the saws that has known big end rod bearing issues and should run at least 40:1 with normal use. Hopefully your rod bearing had no radial play.

 

[Mike Gott]

I had a Meteor pin bearing fail in my 288 after 5 tanks of fuel @32:1 mix. I put the old OEM bearing back in it after I cleaned everything up and has been fine since. Got 20 tanks of fuel through it now


Sent from my iPhone using Tapatalk

 

[Gypo Logger]

It's quite amazing how durable those roller bearings really are, especially the clutch drum bearing.
I agree though with other posters that a fatter mix and slightly richer setting is a must for milling.
Muffler mods also get rid of residual heat.

 

[ft. churchill]

Sorry to hear of your pin bearing failure. I would also go with a factory bearing after having a failure like that. I've never had a pin let go, I'm also on 32:1 full synth oil and muff mods on everything.

 

[John from Cle Elum]

Chris: I originally bought the saw in a basket for $80. The prior owner had taken to a shop that diagnosed the problem as a crank case air leak and they wanted a lot of money to do the work. It had a LOT of other problems. Bearings, piston scored, seals, carb was dirty, flywheel was cracked. I was not sure how it could even get to that point. After all was said and done it as cost a couple of hundred of parts. It was fun. Rebuilding a saw is about the limit of my attention span.

Brad: The saw was intentionally tuned a little rich. I used the method in the workshop manual. Maybe I will push it a little further rich. I will check the play on the crank end bearing. Do you have any idea what the limits would be and how to measure? I would hate to have to split the case again and find a good crank. I was running the oil mix at probably 45 to 1. I will take the 32-1 advice. Increasing the oil content from 2% to 3% is not drastic.

Gyp: What muffler mods would you recommend? This one has been drilled and screened on the top corners by the prior owner.

Now I need clean the cylinder and all the junk out of the case.

Thanks for all the help
John

 

[Chris_In_VT]

John, you said crankcase air leak- early 385's were known to spin the PTO side bearing in the case. What year is this saw, and did the clutch side bearing fit in TIGHT? Did you do a pressure/vac test?

It could simply be that the wrist pin bearing was faulty/ combined with 50:1 and maybe not rich enough for milling. But just FYI on that bearing/case half.