? For those who have worked on more saws than I

[K7NUT]

I am in the process of re-building an 044. From the top, a friend bought it used, so I put a new Meteor P&C in it, did not get more than 10-20 minutes of run time, when it had a catastrophic failure. I figured a bearing let go and when I got the case split, I was right, but it also took out the 10mm crankshaft. Replaced the crank & bearings, but inspecting the new P&C, the can if fine, no marks, but the piston has/had some minor chink marks on the top of the piston and you can definitely tell, it was the clutch side bearing that went, there are small gouges, scuff marks where the wrist pin enters. I know you shouldn’t use emery cloth, but I used it just to get slight blemishes off the top and skirts, but the issue I’m questioning is, the wrist pen no longer slides in/through by hand, it will definitely fight me. So, should I consider this piston not usable, should/would this be an issue, other than trying to remove the pin in the future?
I figure it will take enough force to slide it through the piston, I would need channel locks. Maybe the piston just took too much stress and should be replaced, along with new rings?

 

[Cutch]

The only one that can make the call on this is you. I'm a mechanic by trade and I tend to put my priorities in different places than other people.

Personally? I'd just replace the piston and wrist pin as well since you already have everything torn apart (if you have the money to do so). I am also at the point in my life where I value my time far more than I do most other things. If I need to get the saw working in order to either make money or beat the winter cold for harvesting firewood I'll eat the cost of a few parts to have a 100% surefire working saw. As much as I love chainsaws taking them apart and putting them back together is a bit of a pain in the ass to me. I'd rather be in the wood than in the shop wrenching.

In terms of serviceability I would say that due to damage it's no longer serviceable. If you know a machinist you could see if they could re-bore the wrist pin and also maybe find a larger wrist pin size for the piston.

 

[pioneerguy600]

The wrist pin can be a very tight fit in the piston, the older saws often required a pin press to install them, some just required heating the piston. The pi is held captive in the pin bore ,the rocking motion is provided by the pin bearing on the rod end so if the pin will push in and the circlip can be installed correctly everything would work fine. There does not appear to be enough damage to prevent me from using that piston in my own saws, if repairing for someone else I would go with a replacement.

 

[Mad Professor]

The wrist pin can be a very tight fit in the piston, the older saws often required a pin press to install them, some just required heating the piston. The pi is held captive in the pin bore ,the rocking motion is provided by the pin bearing on the rod end so if the pin will push in and the circlip can be installed correctly everything would work fine. There does not appear to be enough damage to prevent me from using that piston in my own saws, if repairing for someone else I would go with a replacement.

+1, where it needs to pivot is on the upper bearing. Many cars/trucks used press fit pins with no retainers.

If it is misaligned, that could be an issue

 

[pioneerguy600]

+1, where it needs to pivot is on the upper bearing. Many cars/trucks used press fit pins with no retainers.

If it is misaligned, that could be an issue

In this case I really doubt that, this piston did not receive that much pressure damage. I have seen them with deeply embedded bearing needle bits with no real damage to the pistons further function. New parts are always preferable for peace of mind but very often slightly damaged parts like the one shown will last a good long service time. I learned a whole lot in my early years working in a remote ,far from any new parts replacement environment where machines of all types needed to keep on producing until new replacement parts could be shipped in, weeks or even months before they could be had in hand so I got to see a lot of saws and other machines run on parts that were much worse than the OP`s piston. Making gaskets and filing parts, were common fixes to keep engines running, gas,diesel and electric were all needed around the mills.

 

[Patrick62]

First inclination would be, I would run it.
If another was handy, I would swap it.
should have posted this in the chainsaw forum, but anyway.