Plug electrode gone!

woodworkingboy

woodworkingboy

TreeHouser
Joined
Aug 16, 2008
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A guy brought in a 372xp that wasn't running right or not at all. One of the things that I quickly found wrong with it was that the plug was loose in it's seat and upon removal, the outside electrode was completely sheared off. I guess that happens from a plug vibrating when loose, and he said that he was hearing a metal against metal sound before it quit on him. I've never seen a plug in otherwise good shape missing an electrode before. Nothing shook out upon turning the saw upside down and pulling the starter. Wonder if it's still in there or got blown into the muffler? Seems potentially quite damaging if still in the cylinder. I'll have to pull off the muffler to see if anything wants to shake out. The guy said he'd pay to have the cylinder removed if need be. Quite a nice saw, but i really wasn't wanting to have to pull the thing apart very much.

No basic maintenance had been done on the saw it appeared, the air filter was packed and the carb was also loose against the boot, probably was sucking some unwanted air. I'd like to tell him that I'm taking the saw away due to poor care. :)
 
I had a log splitter that I thought broke a throttle linkage it would run wide open all the time. A couple years later the muffler finally rusted off and when I picked it up out fell two tiny little screws. They made it through the intake and out the exhaust somehow. One was kinda flattened. A few years after that the engine called it quits. I tore it apart just to look at it( I mean might as well take a gander and maybe learn something). There was a perfect imprint of the screw in the top of the piston. I'm guessing the tip is in the exhaust as long as there is a spark Arrester
 
It seems the Stihl 441 had a tendency to rattle the plugs loose for unknown reasons .I don't know if they still have that problem or not .
 
  • Thread Starter Thread Starter
  • #4
Thankfully I found the busted off electrode in the muffler, good call, Rich. No need to pull off the cylinder.
 
Usually when electrodes come of it is from faulty plugs or heat.
I seen this happen on all plugs regardless of brand.

When it drops and saw is leaned forward it goes out and this is usually very lucky..
If it is on the side, it has no were to go and get pinched or worse.

Make sure there is no damages, inspect piston and head carefully.
Get new correct plug and make sure it is good before mounting.
 
  • Thread Starter Thread Starter
  • #8
i know it was a running saw before the recent problems. With a new plug and some other attention, it is running in good shape now. The electrode lost it's little curve where is is attached to the plug, i think it got smashed between the piston top and cylinder top before exiting into the muffler. The piece is thicker than what a typical stock squish would be. The saw all in all seems ok though.
 
  • Thread Starter Thread Starter
  • #10
Good point. I always ask some questions when people want a saw looked at. How long has it not been running, and did it just suddenly stop or were there ongoing problems....those kinds of things. It helps to pinpoint what is the trouble. People can be surprisingly vague though, and there are the ones that have been sitting in the shed for a couple years and people's memories don't go back that far to when the saw was still being used. Sometimes I get compelled to ask, when was the last time that you cleaned it?
 
You should look were damages are. If you are lucky there is no, but that is very rare.
When electrode drop, even if it is almost glowing it still is harder than piston and cylinder.

I have seen fragments come of piston, stuck rings, scratches etc that will make saw perform less or blow up eventually and still run.
 
  • Thread Starter Thread Starter
  • #12
I'm sure that you are right, Magnus, the cylinder and piston should be checked out.
 
Shit, for the way this fellow takes care of his saws, I would just tell him to run it till it dies.

My dad fixed up a really nice pickup for my sister and I to drive in high school. She blew up the engine and I rolled it.

Some people should not have nice things.
 
Back when I was working on Bobcats we got a call from a rental company. They'd been running an old beat up unit, it was BAD! In the shop once a month, if not more, just falling apart! They finally broke down and bough a brand spanking new unit, top of the line! Had it less than three months and we got a call it wouldn't start. We send a field mechanic out.
His story,
"I get there and something just doesn't look right, I open the back door and see a water line half way up and the air filter housing was full of water. I looked at the tracks behind it and it looked like it had been drug from the back yard. I follow the tracks, it goes behind the fence, makes a 90 deg turn behind the garage, along the side walk, then I see the tracks going down the side of the pool!"
We've no idea how they got it out! Took us two months to go through the thing and get it running again. People don't care about anything anymore, they just run it into the ground then complain it's broken!
 
Once again the Humble Magnus takes another American to school.

Either that or I was against the idea of doing a full tear down because it would be wasted on a jackwagon who wont take care of the dang saw anyway.

You can polish the shoes of a man who works in a milking barn, but whats the point?
 
Hey, Magnus! I've been away from this forum for awhile. Your writing in english seems to me to be getting much better, and I appreciate the new humorus approach shown in the writing.

It is always good to read whatever you post relating to saws; thanks for your contributions.

Tim
 
Thank you for kind words.
Learning curve is not as steep as it was 10 years ago and still pick up something now and then..
But expressing in words is not my strongest feature regardless of language.
 
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