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Stihl 390 chain saw decompression valve coming apart!

Started by shiftright, October 05, 2008, 06:55:39 PM

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shiftright

I have a Stihl 390 chain saw that is three years old that I have used to cut my own firewood (residentual use) I probably cut about a total of 20 cords of wood with it at this point. I was cutting with it yesterday and it made a terrible noise and stopped running. I pulled the starter cord and could tell it had lost compression. I started checking into it and I noticed that when I pushed on the decompression valve that it didn't feel normal. I took off the rubber cover and sure enough the middle of the valve was gone. I removed the rest of the decompression valve and looked into the cylinder and seen the rest of the valve stuck in the piston.  It looked like a big rivit or roofing nail. I was wondering if anybody else has had issue with the decompression vale coming apart? If so has Stihl compensated them with some labor or parts? I really don't see how this could be caused by anything that I did but with it three years old. I got bad feeling I'm on my own! Any thoughts would be appreciated.

Rocky_J

I believe the decomp valve just screws into the side of the jug, sort of like a spark plug. At least on the Huskys they do (13mm socket). Spin it out and then go hit up your dealer for another one.  8)

John Mc

With the rest of the decomp valve stuck in the piston, he might have more to fix than just replacing the decompression valve.

John Mc
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Lanier_Lurker

Egad... :o

I need to watch this thread since I own an MS390.

shiftright

I sent in an e-mail to Stihl this morning as that is the only way to contact them. I'm currently waiting on a reply. Fingers crossed!

sawguy21

Do you not have a dealer nearby? The saw is out of warranty and it will be a costly fix if you are not able to do the work. This is not a common problem with the MS390 or any other recent Stihl model but I remember them falling out of the 075AV. There did not seem to be a way to keep those beggars tight.
old age and treachery will always overcome youth and enthusiasm

shiftright

Hi Sawguy21, I do have a dealer in the area (the one I bought the saw from) and when I called they told me with it three years old that it was simply not under warranty and suggested that I get a hold of Stihl directly as they might do something for me. If Stihl doesn't help me out I will do the repairs myself, but my opionion of Stihl will not be as high as it once was!


joe_indi

Unless the knob comes off, and a bit of flattened bit of the stem wears out, the chances of the decompression valve falling into the cylinder are very rare.
You will need to open up the engine completely to do a thorough clean up.
This is because that 'rivet' like bit stuck on the piston is not the only component in the decompression valve. There is a mustard sized tiny steel ball and a tiny spring.These too must have fallen into your cylinder.
You can never know what kind of mayhem both these will create if left to roam around in the crankcase, especially within the crank bearings.

Joe

shiftright

Joe, I do not know why the vavle came apart. It appears this is a one off deal and I'm the lucky one to get it. I still haven't heard anything back from Stihl. If I end up doing the repairs myself I will open up the engine as I figured it had more parts than what I see stuck in the piston. This whole thing bums me out as the saw isn't very old and really hasn't been used all that much. I took good care of it by cleaning it after each use and storing it in the case, always used the Stihl chain & two cycle oil and at leat 89 octane fuel. Sometimes your the widshield, sometimes your the bug... today I'm the bug!

Kevin

Your dealer should be contacting the Stihl rep, not you.

sawguy21

That is my thought too although from the dealer's point of view there is no argument. The warranty has expired and his responsibility has ended.
old age and treachery will always overcome youth and enthusiasm

LeeB

Yeah, but he might want to sell another saw someday.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

John Mc

If I were a regular customer, I'd at least hope the dealer would make some initial contact with Stihl, and perhaps find out if this were a known problem. There is not enough $$ in a typical chainsaw for him to run to Stihl for every case of a disappointed saw owner. However, this does not sound like accident or abuse. It sounds like a design or manufacturing problem.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

shiftright

After reading the comments on this thread I went back to the dealer that sold me the saw and insisted on seeing the owner and not just the counter person. The owner charged me $40.00 to inspect the saw and said he would reimburse me the money if he could get it covered by Stihl. After three weeks at dealer I had not heard anything so I decided to call today. I got a hold of the service department and they informed the parts have not showed up at this point and that they would call me when it's done. I asked if Stihl was going to cover it under warranty and the service guy said he did not know as the computer screen did not say either way, but he did say if they didn't call me ahead of time to get an approval on the parts order then it was probably going to be covered as the cost of the parts were in excess of $240.00. With this kind of money for the parts they would traditionally get an approval from the customer before ordering the parts and since they didn't do that he figured it was going to be covered. Here's me crossing my fingers  ???

isawlogs


Well I think that they could of called and let you know either way ...  ::) Would not have been too costly to make a phone call and tell you that it was being taken care of ...
A man does not always grow wise as he grows old , but he always grows old as he grows wise .

   Marcel

rebocardo

> then it was probably going to be covered as the cost of the parts were in excess of $240.00.

They sell on E-Bay for less, I have been tracking them. I saw one locally for only $125 at a rental place and if I had a spare Ben in my pocket I would own it already.

shiftright

The dealer told me they would pay half of the labor and parts. My half would be about $200.00 plus tax. I told them I was disappointed as that would mean that the full cost would be close to a new saw. The dealer told me his Stihl salesman said this is above what they would normally do as it is out of warranty. I called the 1-800-gostihl phone number and got a hold of a gentleman name Nick. Nick investigated my dilemma with the dealer and offered me a new MS390 for 320.00 plus about 20.00 to ship it. This would not include a bar and chain as my old bar and chain is fine. I told him I appreciated the offer but was disappointed that a saw now cost me over 700.00 as I paid 399.00 for the original saw. Nick did point that I did get some use from the original saw and that's worth something. I then asked Nick if he would be willing to get me a better price for a MS361 as I see nothing but great reviews on this site for this model. Nick promised me he would contact my dealer and see what they could offer me after he and the dealer put their pencils to paper to see what price they can offer me on the MS361. I'll keep you posted.

shiftright

Ooops! I made a mistake on my last post. I originally paid $499.00 for the MS390 saw. I received a call back from Stihl and they offered me the MS361 for $405.00 plus about $20.00 for shipping. I would be looking at about $458.00 out the door for the saw after taxes. I'm not sure what I'm going to do as it's a decent deal for the 361 but I still have to come up with substantial amount of money. I'll have to think about it. :-\

timber tramp

I would strongly consider ponying up the $458.00 for a new MS361. I priced new saws the day after Christmas, and the MS361 was 680.00 w/24" bar and chain at my Stihl dealer. Sounds like a pretty good deal to me.
Cause every good story needs a villan!

shiftright

Thanks for your opinion Timber Tramp. The MS361 at my dealer was $609.95 with an 18 inch bar & chain. The price they gave me for $405.00 was without a bar and chain, but they would swap my old bar & chain onto the new saw for me as they are still good. (big deal!) Anyways I would get the 1 year warranty with the new saw and no warraty with the repair. I didn't ask, but I'm sure they would want to keep my old saw as well. I'm leaning toward ponying up the 458.00 bucks.

timber tramp

   Might be a good decision. Have'nt heard (read) anything too bad about those saws. Been thinking of buying one myself.
Cause every good story needs a villan!

shiftright

Okay I went and bought the MS361. The dealer gave me the MS390 back as well, but in a box all apart. I think I might try to repair the 390 down the road as I could always use an back-up/extra saw. The dealer also gave me credit for the original $40.00 I gave him for the inspection of the 390 saw. All in all I'm pretty satisfied with the outcome as Stihl and the dealer could have told me to go pound salt as I was out of warraty so I got to give them both credit for working with me. I'm going to call Nick at Stihl an thank him personally for helping me out. I also appreciate the insight everyone offed on this site as well-Thanks!

isawlogs


I am glad to hear that you got satisfaction out of this . Nice to know tht there are still some companies out there that have there clients at heart .

You stick around and let us know how the saw works out for you .  :)
A man does not always grow wise as he grows old , but he always grows old as he grows wise .

   Marcel

shiftright

I agree isawlogs. I don't no if any other company would have worked with me on this issue. Hats off to Stihl and my dealer for stepping up to the plate. The only concern I have is the 361 has the decompression valve....once bitten twice shy! I could remove it and plug it but the dealer told me after the breakin period the saw will have about 180 lbs of compression so I might want to leave it. He really feels this will not happen again as he has never seen it in the past.  I hope he's right!

I did take a couple of cuts with the new saw and it definatly has a lot less vibration than the 390 and the power seems to be right where you would expect it to be for a new saw of that horsepower.   ;D

MrJim

I repair Stihl, we would charge less then $25 for the part AND labor. 


UNLESS the cylinder was badly damaged.

You need a thin walled, deep socket to remove.

Sounds like a ass for a dealer tho.  Some BIG dealers have high over-head and must pay the shop tech lots and will not deal, but here the best advertising for Stihl is a trip to the other guys repair shop.

Something this simple, with help from here, you could have done the repair yourself.  Buying just the part from your dealer would have been cheap. 

And no, have never heard of this before.


I just got a MS 361 CB, sweet.  I keep a 24" bar for the times I need on, but use 20" to do most of my stuff.

shiftright

Mr Jim,

I agree that the dealer probably could have fixed it a lot cheaper than what they quote me. Unfortunatly the saw was 2 years out of warranty so they did not have to do anything but they did choose to offer me a discount on new saw.

The cylinder on the saw has some slight damage on the head area, but the cylinder itself is still perfect. I'm going to clean up the head area a little and pop a new piston, rings & wrist pin in it. I have the OEM piston on order, but it is $80.00.

Is the piston that you spoke of an OEM part? I'm a little gun shy of off-shore parts  ;)

By the way, when I go to put this together were will I have to use that thin wall socket?

Thanks

30dodgeboy

Quote from: joe_indi on October 07, 2008, 10:05:17 AM
Unless the knob comes off, and a bit of flattened bit of the stem wears out, the chances of the decompression valve falling into the cylinder are very rare.
You will need to open up the engine completely to do a thorough clean up.
This is because that 'rivet' like bit stuck on the piston is not the only component in the decompression valve. There is a mustard sized tiny steel ball and a tiny spring.These too must have fallen into your cylinder.
You can never know what kind of mayhem both these will create if left to roam around in the crankcase, especially within the crank bearings.

Joe

Sorry to bring up such an old thread, but...

I have a Stihl saw that grenaded the decompression valve when trying to start it.  The pin fell down into the cylinder and jammed the piston.  While the piston and cylinder appear OK, does anyone know exactly how many other parts there are to that decompression valve?  I assume the detent mechanism consists of spring loaded balls, but just how many are there?  I am planning on disassembling the engine to verify none passed through the transfer ports, but want to know how many other parts there are to that little troublemaker valve.  Thank you in advance,
Art




joe_indi

Art,

Three things can fall into the cylinder from the valve, the valve stem(the rivet shaped item), a small(tiny) steel ball and an equally small spring.

Joe

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