Hope I didn't mess up anything

[Keithandstef]

Well, after I got home from work I tested the compression on the saw. To my horror, the insert of the compression tester is making contact (it sounds like) with the top of the piston. The top of the piston looks great, but it's clear something is amiss. It didn't do this before. Is it something simple, or does it appear I did in fact bend the rod? Why would it be higher than normal if bent?

 

[rob066]

I never use a piston stop on a Husky. Just use the little notches on the clutch to knock it off.

The 257 doesnt have the notches like a 346 etc. It is a 15mm hex only unless it is the newest updated version clutch

 

[HarleyT]

If you bent the rod any, the piston would not go up as high.

 

[Keithandstef]

Well, it's knocking like crazy when I do the compression test. Sounds like it's hitting the tester valve. And the saw is hella hard to start now. I can't get a good compression read due to the knocking and not allowing a good group of pulls. What gives?

I'm pretty sure I fired her up once I had it all back together and it ran fine. Not sure what's going on here.

 

[rob066]

You may have possibly broke the piston pin bearing.

 

[HarleyT]

Well if it is hitting the compression tester, quit pulling the rope.....

 

[HarleyT]

Take out the tester, and peek at the top of the piston, and look for marks.....

 

[Keithandstef]

Well if it is hitting the compression tester, quit pulling the rope.....

Ya I know, but it's worth mentioning since it never did before. I've stopped testing her and have moved on to what to do next. I lack the skill to take the top end off and fix this saw. Is there a place on this site to find folks near me in St. Louis who could help out a fellow Arboristsite member?

 

[HarleyT]

Fix what? I'm not convinced that you have a problem yet.

 

[HarleyT]

Put the plug back in and start the saw.

 

[HarleyT]

Look at the plug tip. Is it bent?

 

[CascadeHusky]

My tester had two hose attachments that fit the threads. One has much longer threading, and is not for chainsaws...you didn't just mix up, did you?

 

[HarleyT]

yeah, post a pic of your tester threads.

 

[Keithandstef]

My tester had two hose attachments that fit the threads. One has much longer threading, and is not for chainsaws...you didn't just mix up, did you?

No. I never changed it. But here's a weird wrinkle. I have another 257, and here are a couple findings in the last ten minutes:

1) Tester is knocking the piston on that one too. I'm not doing anything different than before when I've tested these saws. I wonder if the pin got weak and is sticking out for some reason? No reason for both to all of a sudden be hitting the tester.
2) The dang start button on the one I've been writing about all along has gone haywire just like my other 257. It sparks when in the off position, and not in the on position. The saw runs pretty well (but not great) when I remove the dead wire for the starter. I let it warm up in my garage but don't have anything to saw right now. It doesn't restart well, but I have to kill it by pulling the choke since the starter is shot.

Hmmmm. It appears my tester has an issue in that it's running too deep in the cylinder. Picture below.

 

[Keithandstef]

Ok, another update.

I don't have any idea what's going on with this saw. Put the tester in it again and it registered kind of low compression while warm (130 psi) and it's not making the knocking noise any more. I really don't know where it was coming from (the noise). It felt like the cord was slipping and it made a metallic sound when it slipped. Makes no sense to me.

The saw doesn't want to run and is near impossible to start. I've been starting and stopping it alot, so maybe it's pissed from that. I dunno.

 

[Marshy]

You may have possibly broke the piston pin bearing.

The piston pin is hardened steel. He'd have a bent rod or broken piston before the piston pin broke.

 

[Keithandstef]

I pulled the muffler and looked things over through that spot and the spark plug hole. All looks good. I am still at loss as to what that clanking noise was when I was doing the compression tests. Looking at the tester, there's no way the end of it was hitting the piston. It's shallower than the spark plug. It was weird that both saws did it though. The common issue was I had changed the sprockets on both. The pull cord would sort of slip and it would make a loud "clank" noise. And the cord would sort of catch. Couldn't do the compression test as a result.

Would a bad seal with the tester create this issue. Sort of a half seal making something clank? I don't know what else would create the same issue for both saws.

I really appreciate everyone's input and help.

 

[Keithandstef]

Spinning crank backwards?

How could I do that during a compression test? I'm just yanking the cord like mad. I'm digging the attempts at an explanation though. I'm clearly lost.

 

[CascadeHusky]

Sorry I hadn't kept up...I was imagining you spinning by hand now...

 

[Keithandstef]

I pulled the muffler and looked things over through that spot and the spark plug hole. All looks good. I am still at loss as to what that clanking noise was when I was doing the compression tests. Looking at the tester, there's no way the end of it was hitting the piston. It's shallower than the spark plug. It was weird that both saws did it though. The common issue was I had changed the sprockets on both. The pull cord would sort of slip and it would make a loud "clank" noise. And the cord would sort of catch. Couldn't do the compression test as a result.

Would a bad seal with the tester create this issue. Sort of a half seal making something clank? I don't know what else would create the same issue for both saws.

I really appreciate everyone's input and help.