pin came out of piston

[cedar hacker]

Got my 290 with a 390 jug on it apart after it ceased up today. Turns out the little wrist pin that holds the rod thru center of piston came out and bounced all around inside trashing it.iv had 2 months or so and i called the company and warranty was for 30 days.what a bummer. Has anybody had this happen before. Its a first for me

 

[fearofpavement]

Unless the piston broke in two, that isn't possible.

 

[thomas1]

I think he means he broke a circlip.

 

[cedar hacker]

There is 2 little half ring clips on each side of piston that hold that rod that goes through the piston and the lifter arm.it was the lilttle half ring clip that came out.i know this because one side is missing and you can see were it sheared the piston were it was and pieces of it inside cylinder. So i do believe its possible.

 

[fearofpavement]

Well, a circlip can certainly cause havoc, if that's what the OP meant, then it isn't described well.

So, OP, what came loose? The circlip that holds the wrist pin (piston pin) ? Or did the piston pin come out?

Ok, saw your update and understand what happened now. Bummer!
It'll take another piston and cylinder kit to repair it and make sure to check the bearings too in case debris got into them.

 

[thomas1]

There is 2 little half ring clips on each side of piston

Those are circlips.

that hold that rod that goes through the piston

That is the wrist pin.

and the lifter arm.

That is the connecting rod.

it was the lilttle half ring clip that came out.i know this because one side is missing and you can see were it sheared the piston were it was and pieces of it inside cylinder. So i do believe its possible.

It is indeed possible. It's just that your terminology was a little off making your post somewhat confusing.

 

[cedar hacker]

Yeah sorry. When i started working with saws i just started taking my good one apart to see what it was supposed to look like.from there iv been just figuring it out as i progress

 

[RiverRocket]

Always pays to use OEM circlips and to install them properly....expensive lesson.... :bang:

 

[Stihlofadeal64]

The circlip "saga" has been gone over with many threads here. Most sawguys are recommending to try to use the OEM clips instead of the aftermarket "curlie" clips with ears on them. (You'll have to find one that will fit the machined groove in your piston though (on the next project that is...). Looks like it's back to the drawing board on this one.

 

[ChainLightning]

There is 2 little half ring clips on each side of piston that hold that rod that goes through the piston and the lifter arm.it was the lilttle half ring clip that came out.i know this because one side is missing and you can see were it sheared the piston were it was and pieces of it inside cylinder. So i do believe its possible.

Everytime I rebuild a saw down to putting in a different piston, I always sit there and make sure the pin is exactly in the middle and that both little groves that the snap rings are visible. Then I take extra time making sure the clips sit in there perfectly and snap into that groove. Even after I take all that time, When I go to fire up the saw, I still get that gut sick feeling that something is going to let loose, but it has not yet. knock on wood.

 

[514mach1]

I've only used about 5 or 6 aftermarket pistons, and so far only 1 has come with circlips that were worth using. After having a new cylinder and piston trashed by a cheap circlip (ran a couple hours after the rebuild), I don't use cheap circlips.

 

[cedar hacker]

Yup,chalk that one up.lesson learned

 

[watsonr]

Lots of guys are taking a pair of side cutters and cutting that little dog ear off... problem solved. Mastermind has had some good success doing that and I'm doing that as well, not an issue to speak of. Lots of my rebuilds are going into the hands of tree service guys here locally and even my Stihl dealer is doing the same thing!

Nice thing is that my tree guys are willing to test lots of stuff for me and don't mind that I want saws back to tear down and inspect after a couple weeks... they're getting free parts! Seems it's always that little extra ear..... cut it off!

Find a dealer that gives a better warranty:msp_smile:

 

[thomas1]

Lots of guys are taking a pair of side cutters and cutting that little dog ear off... problem solved. Mastermind has had some good success doing that and I'm doing that as well, not an issue to speak of. Lots of my rebuilds are going into the hands of tree service guys here locally and even my Stihl dealer is doing the same thing!

Nice thing is that my tree guys are willing to test lots of stuff for me and don't mind that I want saws back to tear down and inspect after a couple weeks... they're getting free parts! Seems it's always that little extra ear..... cut it off!

Find a dealer that gives a better warranty:msp_smile:

Is the issue that "ears" are breaking off the clip, or that the "ears" are allowing the clip to walk out of the groove?

 

[watsonr]

Is the issue that "ears" are breaking off the clip, or that the "ears" are allowing the clip to walk out of the groove?

Ears are breaking off or in the case of "walking out", there actually bending the clip and it looses it's spring because the clip is so stiff. My dealer is doing it as well, he's ham handed and is bending the clips! I watched him assemble a 200T the other day with a Hyway kit and he bent the clip. If I hadn't been there when he did it, he'd have never known it happened.... got to pay attention. I made him pull the clip and sure enough, bent!