Ring locating pin failure

[idiotwithasaw]

This is what happens when a locating pin comes loose on a 372 xp xtorq piston. Nice little groove right where you don't want it to be. I got this saw as a parts saw I don't know how long it ran like this or how long it took to do this much damage.

 

[Canadian farm boy]

Wow. I'm kinda shocked that that's all the damage it caused.

 

[idiotwithasaw]

I am too. If it had actually came out I'm sure it would have.

 

[Mastermind]

Debur that....put in a new piston and go again. I bet it wouldn't even hurt compression much.

 

[Definitive Dave]

is this just a fluke manufacturing thing or is there something that the builder or owner did wrong to make it come apart like that?
I haven't seen that in real life ever
Dave

 

[Onan18]

I have, manufacturing fluke more than likely. Had one like that the other week on a RedMax weedeater.

Joe

 

[d.l.d]

Saw the same thing on an fs45 last spring. I'd also say manufacturing flaw. It came all the way out and wedged its self between the p/c. I thought it was a bent connecting rod at first because ive seen that on those stamped steel rods before. Once i opened it up i saw the rod was fine i had to see why it was seized as the cylinder though the exhaust port looked fine. Once i finally got it free that was the culprit.

 

[idiotwithasaw]

It's a pretty deep groove at the very top. It is probably a mm deep and extends half an inch from the top. It also wore the ends if the ring till they were rounded. If I didn't have a OE cylinder that's waiting on a meteor piston I might be tempted to do as you suggested mastermind. If nothing else be interesting to see how well it could possibly run as it is.

 

[idiotwithasaw]

The bad thing is I don't wanna have to split the case but I'm not sure I can flush all the fines out of it. What do you guys think. Flush it real good or split it and new bearings?

 

[Marshy]

Finger ported?

 

[Canadian farm boy]

I'd pull the crank seals and flush the bearings with gas and or brake clean and maybe even some shop air. If after a thorough flushing I wasn't happy I would then split the case. If you dump out the brake clean/gas from the crank case on a clean paper towel you'll be able to see what your flushing out. Keep flushing and dumping onto paper towel till you don't see any more glitter on the paper towels.

 

[Marshy]

Brakekleen will dissolve the paint in the case, not good. I'd use gas personally.

 

[Canadian farm boy]

Brakekleen will dissolve the paint in the case, not good. I'd use gas personally.

I've yet to experience this. I'm not saying your wrong and I'm right. I'm fairly new to rebuilding saws. This is how we all learn

 

[idiotwithasaw]

I hate to pull seals, especially if they r still good. I have tried flushing it with kerosene and starting fluid. I also took peices of paper towel and stuffed it in thecrank and rotated it wiping it out inside. I kept doing this and then flushed it more

 

[beaglebriar]

How much junk was in the bottom? I'm guessing not much.

 

[d.l.d]

I hate to pull seals, especially if they r still good. I have tried flushing it with kerosene and starting fluid. I also took peices of paper towel and stuffed it in thecrank and rotated it wiping it out inside. I kept doing this and then flushed it more

Just a suggestion of what i do to get all the fines out. At this point you already have the p/c off, i fill the case with gas and gently chuck a drill on the clutch side of the saw. Holding the connecting rod where the wrist pin is so it can move without banging all over the case. I run the drill forward and reverse then dump tbe gas in a clear container and repeat the process till i see no debris left.

 

[idiotwithasaw]

Apparently there is no quote feature. But no there wasn't a whole lot that was visible in the bottom of the crankcase. I wouldn't think there would be a lot. I'm gonna flush it a few more times. Just to be sure.