My cousins Stihl 029 Question

[Jeff Lary]

As Fish said, it looks like you got the right piston. Without pictures, I am not going to offer advice on the saw. I am, however, quite curious as to why you are so interested in repairing the saw for your cousin? It sounds to me like he is just going to shred it again.

Well now that is a good question, I just know he does not have a bunch of extra money and everyone told him to throw it away.I orig offered him $25.00 for it so I could try to fix it for the learning exp. But when he heard me offer him 25 he said "well if you can fix it for you,... maybe you can fix it for me? It would be a whole lot cheeper than me buying a new saw , sooo what do ya think cus" So I said sure But my main concern is I think I should be the one to try cleaning the cyl this next time but I have never cleaned one before . I have read about heat the cyl / wipe the transfer with Muriatic acid But thats all I know ( ie ) what ive read.

 

[Jeff Lary]

Pictures

I took the saw back today and tore it down again to see if i could find somthing wrong up inside the cyl on the exhaust side.I figured he must have left a little transfer on that side of the wall and that was what scratched the new piston.Well long story short, the wall looked and felt fine to me.I took some 600 grit w/liquid wrench as a lube and went at it anyway.Dont think there was a ting there but I did clean it some more. In the end I think I found the issue maybe as you can see in the photos.The casting on the bottom of the cyl was extreamly rough so when I put on the three bond I used too much I think to compensate for the rough surface.Some of the 3-bond went over and got on the seals so I hope that this was the issue as you will see. Because basically there is nothi ng in that cylinder that can be felt. pic 0022.the old orig piston that we replaced exhaust side, 0023 intake side of same orig piston,0035 the new piston with 10 min run time,0038 way too much 3-bond see the rough casting,0042 exhaust side of cylinder,0050 what the crank looked like w/3-bond all over it when I took it out note the bond on the seal,0051 the new piston and seals all cleaned up. As far as I can tell she is ready to go back together.I was wondering what if you put the 3-bond on now then after it set up then install the cyl? wouldnt it act like a rubber gasket then as well?View attachment 282721View attachment 282722View attachment 282723View attachment 282724View attachment 282725

 

[Jeff Lary]

last two photos

View attachment 282726View attachment 282727
The last photo shows the new piston with the scratch side up ,all cleaned up as far as I am concerened. I will add one more to show how rough the mhale casting is you cant see it very well in any other picture.View attachment 282728

 

[Fish]

View attachment 282726View attachment 282727
The last photo shows the new piston with the scratch side up ,all cleaned up as far as I am concerened. I will add one more to show how rough the mhale casting is you cant see it very well in any other picture.View attachment 282728

You had another lean seizure

 

[Fish]

This is painful, you need to go back and fix the saw first, then replace the piston.

 

[Jeff Lary]

What do you mean fix the saw first ? I guess what i mean is I dont see anything to fix.I cant see anything wrong. It is still all apart as of now just sitting there.
There is a scratch but it is extreamly small maybe 1/2 a mm wide and deep enough that if you press your fingernail against the face and drag it you can feel a slight,...scratch . He is not gonna buy a new piston no way .At least I dont think so he has $90.00 in that one.

 

[Fish]

you need to find out why you are melting pistons first.

 

[Jeff Lary]

Got ya,.. when we put it together I noticed the rough casting so I put a little more 3-bond than you normally would. When I just took it apart there was some 3-bond out on the seals and bearings could this be the reason it sucked in some air? It has new impluse , new gas line , new seals, and a very closely inspected carb intake boot looks great? where else could I look for trouble?Thanks for the help Fish.

 

[tomdcoker]

It's one of those things, we rolled that saw 20 times and cannot see any missing anywhere but I will tell him to look near the muffler. Thanks tom

There are two plugs by the muffler. One on the outside that is obvious and one on the inside. you will have to remove the muffler to install the one on the inside. Tom

 

[Jeff Lary]

Yes Tom I think that was the one, Eureka !!