391 rebuild, HELP! Please?!

[michaelmj11]

well, today

Well, I would like to learn how to work on my own saws (or just small engines in general) but also because, as said in other posts. An retired associate/family friend had been working at the dealer, and was going to do the work for me, but for some unknown reason he did not/was not able to, even though he took it all apart.

So since it was in a box the dealer really did not want to tie his mechanic up with something that in the end might #1 not run and #2 not be worth paying for the labor

 

[tree monkey]

just wondering

 

[michaelmj11]

just wondering

No problem, I invite comments hints, tips etc. I didn't have much time to type as we were just sitting down to dinner. Sorry if I was abrupt.

 

[tree monkey]

inspect those bearings close
clean all the old sealant off the case
I recommend using dirco, that's what stihl uses
be very careful with the piston ring

 

[michaelmj11]

inspect those bearings close
clean all the old sealant off the case
I recommend using dirco, that's what stihl uses
be very careful with the piston ring

Careful how, or of what?

 

[lwn9186]

I would take the crank out, check the bearings and replace the seals.

 

[tree monkey]

Can I use my 034 or not?

Careful how, or of what?

don't break them

 

[michaelmj11]

don't break them

You are talking about the two black metal bands that have some spring to them, located on the top 1/3 of the piston? Right

 

[Milkman31]

I'm lost! The pix I see is of a clamshell saw with the jug removed? Are you not going to tear it the rest of the way down to put new seals in?

 

[tree monkey]

good luck with your project

 

[michaelmj11]

good luck with your project

Thank you, I think I am going to need all the luck I can get.

 

[panteliss]

I'm lost! The pix I see is of a clamshell saw with the jug removed? Are you not going to tear it the rest of the way down to put new seals in?

No need for replacing the seals

 

[michaelmj11]

I'm lost! The pix I see is of a clamshell saw with the jug removed? Are you not going to tear it the rest of the way down to put new seals in?

I had not had replacing the seals suggested before the last hour or two.

I was hoping that one of these two

Purrfect...

At least our answers match lol. I'm gonna go cook supper

Would chime in since they had been helping Monday. I had been waiting to hear back about removing the old sealant (which I saw someone else say to go ahead and remove)

Sooo... that is sort of where things stand. Do you think I need to check the seals and bearings?

 

[panteliss]

I had not had replacing the seals suggested before the last hour or two.

I was hoping that one of these two




Would chime in since they had been helping Monday. I had been waiting to hear back about removing the old sealant (which I saw someone else say to go ahead and remove)

Sooo... that is sort of where things stand. Do you think I need to check the seals and bearings?

See this video is for 390 but not too much diferents with 391 will help you a lot

 

[Milkman31]

I had not had replacing the seals suggested before the last hour or two.

I was hoping that one of these two




Would chime in since they had been helping Monday. I had been waiting to hear back about removing the old sealant (which I saw someone else say to go ahead and remove)

Sooo... that is sort of where things stand. Do you think I need to check the seals and bearings?

Myself I wouldn't bother with any of it if I wasent going to put new seals and check the bearings. I bet if you inspect the old seals they will be kinda egg shaped. And a psi/vac test will be a must after assembly. It's best to do it once and do it right, ask me how I know!

 

[angelo c]

Defiantly seals,
Clean the bearings out in a purple or whatever "super cleaner " you bought. Dry them out quick and feel the drag on the bearings. There should be none.
Acetone ( nail polish remover) or MEK will clear the old sealant fast.

 

[michaelmj11]

Defiantly seals,
Clean the bearings out in a purple or whatever "super cleaner " you bought. Dry them out quick and feel the drag on the bearings. There should be none.
Acetone ( nail polish remover) or MEK will clear the old sealant fast.

Yay, I was about to ask how to get the old sealant off, I was thinking dremel with a wire brush attached, but acetone is an even better way to go imo.

 

[huskihl]

Sorry Michael. Got sidetracked. Your saw is relatively new, so the bearings and seals are probably still good. Popular opinion seems to be straight gas or lean tune caused the scoring. The video above is good watching to familiarize you with the parts of your saw.

Once you clean the red goop off your old saw, find the correct bolts to bolt the jug back on. Apply new sealant around the base cap as well as around the seals outside the bearings and re install the jug

 

[angelo c]

Yay, I was about to ask how to get the old sealant off, I was thinking dremel with a wire brush attached, but acetone is an even better way to go imo.

Honestly, most of it will come off with some rubbing of your fingers. Get the rest w, acetone.

 

[michaelmj11]

Sorry Michael. Got sidetracked. Your saw is relatively new, so the bearings and seals are probably still good. Popular opinion seems to be straight gas or lean tune caused the scoring. The video above is good watching to familiarize you with the parts of your saw.

Once you clean the red goop off your old saw, find the correct bolts to bolt the jug back on. Apply new sealant around the base cap as well as around the seals outside the bearings and re install the jug

Well, for what it is worth, the chainsaw had the same gas in it as was in my weedeater, and the weedeater didn't blow up...... I think what I remember the Stihl verdict was. That I had been keeping the powerhead too close to the logs (so the saw was not getting enough cold air?) , and on top of the logs were too big for it.