Stihl MS390 - Need Advice

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AnotherNettle

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Hello, I am a new member who spent some time lurking and reading before joining. I need some advice on a Stihl MS390 that I bought new about 12 years ago. I run a 25" bar and cut a fair amount of fire wood with it each year (except for a couple where back trouble interfered). It has several problems and I am trying to decide whether to fix it or buy a MS362. If I fix this one, I would probably go for a MS194T or MS201T to cut small stuff and take some duty off the 390 (and me). The saw currently runs and cuts seemingly as strong or stronger than when it was new. Here are the known problems:
-The right half of the clamshell housing is cracked, allowing bar oil to leak while stored.
-The muffler is loose and the remaining bolt spins when I try to take the nut off.
-The muffler is missing everything from the spark arrestor screen out.
-One of the housing bolt holes for the spikes is stripped, allowing the bolt to back out and go missing while in use.
-The brake lever is broken on the right side, just above the pivot.

Obviously some of the items MUST be fixed (e.g. brake lever) and all should be fixed. I have not worked on a chainsaw much before, though I am mechanically inclined. One Stihl dealer quoted parts and labor at about $250 to replace the right housing, muffler, and brake lever, but this is based on my description to them and not an examination of the saw by someone who knows a lot. I've watched some of the videos on MS210 to MS390 conversions to get an idea of what is involved and think I can do the work myself (and think it would be interesting and fun). The main questions are:
-What else should I check before thinking the dealer estimate is complete?
-How is the longevity of these saws?
-Am I about to fix something that is not really worth the time, trouble, and expense?
-Is getting a service manual a good idea (and is there a cheap place to find one)?
-What don't I know about this saw that I should? (This is an appeal to expertise, not a request for clairvoyance.)

Thank you all for your time and sharing of knowledge.

JN
 
Well fist off the oil tank/ housing is one piece on those. The motor clamshell bolts too it. The ms 290,310 and 390 use all the same parts just the engine displacement is different. So you could potentially find a 290 or 310 saw for parts that will fix a lot off your problems. The muffler bolts just zip cut them off and get new ones they just slip into a groove on the cylinder
 
I have a 290 and had a 310. They are good saws in my opinion. I have run an 362 and they are also decent. But doing the work yourself you should be able to get your 390 back up to where it should be You might be able to patch the crack and stripped hole with some kind of expoxy or something. Never had to do that myself
 
I would place a wanted ad for the parts you need...a case, muffler parts, and brake flag. I think you could solve the bulk of you issues with 75 bucks worth of parts.

Go to the Beg For Manuals section of this site...some nice guy there will send you the PDF shop manual and parts list, for free.

Roy
 
Thanks for the replies. I have the manuals now. In reading and watching elsewhere, there have been hints that the crank bearings may be a weak point. Would you suggest I open the motor to check them while I have it out of the housing, or are they likely good if the crank turns smoothly?

JN
 
Thanks for the replies. I have the manuals now. In reading and watching elsewhere, there have been hints that the crank bearings may be a weak point. Would you suggest I open the motor to check them while I have it out of the housing, or are they likely good if the crank turns smoothly?

JN
Never hurts to check. If I was that far I would replace the crank seals as a pm
 
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