Author Topic: Breaking loose a stuck piston  (Read 148 times)

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Offline Al Smith

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Breaking loose a stuck piston
« on: November 28, 2016, 05:05:06 pm »
The subject is a Partner P100 super,stuck tight .Old trick I learned a long time ago ,knock the center out of a spark plug and attach  a grease zert ,.Several ways to do that .

One way which is what I did was use a die grinder with a cut off wheel and grind the metal right above the hex where you put the wrench on .Grind off the ground electrode .By tapping with a small hammer  in and out the center electrode and insulator will pop out .Then use a 1/4" pipe tap and thread the inside of the plug shell .Then install a 1/4" pipe to 1/8" pipe reducing bushing then a 1/8" pipe thread  zert .Another is to braze a 1/8" pipe coupling then screw in a zert .

By pumping grease or oil though the plug hole you can move about any piston .Usually if you move it a fraction of an inch it will pull right out .Not so on this one .I had to pump grease in it until it came out the exhaust port .Then I had to rock it further by using a brass rod on the fly wheel .It was really stuck .

The cylinder and the piston believe it or not are clean,I can save both of them ,needs rings of course .The mains are shot .I'm not so sure if this saw might have been under water at one time although the crank pin needle bearings seem to be okay .
 

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Offline 3000 FPS

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Re: Breaking loose a stuck piston
« Reply #1 on: November 28, 2016, 07:11:34 pm »
Good Info Al thanks.   That sounds like it was a real bear to get out.
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Offline 1manband

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Re: Breaking loose a stuck piston
« Reply #2 on: November 29, 2016, 04:42:57 pm »
heard of the technique........but have never heard of anyone who tried it.  nicely done!

were the ring(s) broke after it broke free?
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Offline dannyupsolate

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Re: Breaking loose a stuck piston
« Reply #3 on: November 29, 2016, 07:28:50 pm »
 When Al Smith speaks newbys  better listen  ;D

Offline Al Smith

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Re: Breaking loose a stuck piston
« Reply #4 on: November 29, 2016, 08:52:12 pm »
The rings were just rusted fast .I wouldn't be surprised if they might be okay .Never the less I'll use new rings on the assembly.

The spark plug was missing ,I ran a tap through it to clean the threads .Evidently for whatever reason it had just rusted up from sitting in some damp place .It didn't have any sign of galvanic reaction so it wasn't on concrete .

I have used the plug/grease gun method on a lot of stuck engines .The last I did was a 300 cubic inch Ford before this saw engine .That one was a hoot .I had all 6 cylinders full of penetrating oil for about a week,knocked it loose with a grease gun full of oil then rolled the engine with a big wrench  .Then lost my concentration and rolled it with the starter forgetting all the oil in the cylinders and drowned myself with oil ,duh .When I got it started and came out of the woods my wife came running out of the house shouting "the trucks on fire ".That thing blew blue smoke for at least 10 minutes .So much for the idea of drowning a plug with too much oil in the mix ,never fouled a one .

Offline Al Smith

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Re: Breaking loose a stuck piston
« Reply #5 on: November 29, 2016, 08:59:29 pm »
Problem with old saws that get banished to the shelf is you never know exactly why they got put there in the first place .Sometimes you can tell but more times than not you'll never know .This one it could be a bad main bearing ,bad ignition or a host of other things .I might or might not figure it out once I dig into it .

Offline RoyM

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Re: Breaking loose a stuck piston
« Reply #6 on: November 30, 2016, 07:56:32 pm »
 ;D I was just visualizing you leaning over that Ford when you hit the starter. Too funny.
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Offline Al Smith

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Re: Breaking loose a stuck piston
« Reply #7 on: November 30, 2016, 08:38:41 pm »
I looked like an oil field worker .Mrs Smith was amused but not surprised .

Offline trail twister

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Re: Breaking loose a stuck piston
« Reply #8 on: December 07, 2016, 11:41:23 am »
OK I have to ask, with the ford 6 banger how did you know what pistons were on the down stroke and which were on the up stroke?

 ;D   Al

Offline Al Smith

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Re: Breaking loose a stuck piston
« Reply #9 on: December 07, 2016, 04:55:25 pm »
Doesn't make any difference.Filled the cylinders with oil,let it soak .Used another plug with an air chuck to find out which ones had the valves closed .

Now on a large cylinder on a 300 it took forever and a day to pump enough oil in to move the thing a 1/4 of an inch .56 MM chainsaw it moves fairly quick .
I found a cylinder that was coming up on compression about half way up .That way it would exert more rotational  power having the crank pin at 90 degrees rotation  .On the saw I unbolted the cylinder and just raised the cylinder rather than  try to rotate the crankshaft .I didn't know if it had bearing damage which it in fact did have .If the crank was hung tight I could have broken something .

 

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