Chainsaw Repair

How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: Al Smith on November 28, 2016, 05:05:06 pm

Title: Breaking loose a stuck piston
Post by: Al Smith 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 .
 
Title: Re: Breaking loose a stuck piston
Post by: 3000 FPS on November 28, 2016, 07:11:34 pm
Good Info Al thanks.   That sounds like it was a real bear to get out.
Title: Re: Breaking loose a stuck piston
Post by: 1manband 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?
Title: Re: Breaking loose a stuck piston
Post by: dannyupsolate on November 29, 2016, 07:28:50 pm
 When Al Smith speaks newbys  better listen  ;D
Title: Re: Breaking loose a stuck piston
Post by: Al Smith 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 .
Title: Re: Breaking loose a stuck piston
Post by: Al Smith 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 .
Title: Re: Breaking loose a stuck piston
Post by: RoyM 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.
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on November 30, 2016, 08:38:41 pm
I looked like an oil field worker .Mrs Smith was amused but not surprised .
Title: Re: Breaking loose a stuck piston
Post by: trail twister 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
Title: Re: Breaking loose a stuck piston
Post by: Al Smith 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 .
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 07, 2016, 04:58:42 pm
Forgot something on the Ford .I also looked at the position of the distributor to determine the cylinder was in fact on the compression stroke ..
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 16, 2016, 05:41:10 pm
Got a couple of pictures showing the piston and the cylinder with the spark plug with a grease zert
Title: Re: Breaking loose a stuck piston
Post by: trail twister on December 16, 2016, 06:26:57 pm
I have the sthil o31AV that is seized. But I can't figure out how to get to the cylinder to take it loose from the crank case.

 ;D  Al
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 16, 2016, 07:04:01 pm
According to the IPL it's held on with 4 socket head cap screws 5m by 18 .M5 would be an M4 allen wrench .Rule of thumb,the socket will be one size smaller than the bolt on a standard socket head ,two sizes smaller on a round head or low cap .
Title: Re: Breaking loose a stuck piston
Post by: 3000 FPS on December 16, 2016, 11:32:58 pm
I have the sthil o31AV that is seized. But I can't figure out how to get to the cylinder to take it loose from the crank case.

 ;D  Al

You see those holes in the top of the cylinder.    That is where you put your allen wrench or torq wrench to get to the cylinder bolts.
Title: Re: Breaking loose a stuck piston
Post by: trail twister on December 17, 2016, 04:31:08 am
 ??? It's the plastic stuff I can't get past. Got a whole Jar full of screws removed and that plastic keeps hanging on.

 ;D  Al
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 17, 2016, 05:25:18 am
What,the shrouding?The 031 is kind of a weirdo.The cylinder if I remember is at a 45 degree angle,not horizontal and not vertical .Who knows what they were thinking,too much schnapps perhaps .I've only seen two in my lifetime.One I tuned for a guy and the other in a dealers dead pile .

From what appears on the IPL the whole top cover goes from the top part of the rear handle clear up over the top in one piece .You get all the screws out of it it's bound to come off .Some of the older Stihl models they got real creative where to hid the screws ,like it was a game or something.Some models and this is probably one of them you nearly have to field strip them to get to anything.consider who made it .German engineering is fine work but complicated by design .I could ramble on for hours about that but I'll stop now .
Title: Re: Breaking loose a stuck piston
Post by: trail twister on December 17, 2016, 09:26:11 am
Want it to go from this.
(http://i729.photobucket.com/albums/ww294/joe25da/saw061.jpg)

To this for a start.
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSJcIlpsKPPE7PMYsO-aKtsW9ZHAkurYsI8Ql_K1OxnBz9Zk901)

And possible to this.
(http://i.ebayimg.com/images/g/qFoAAOxyRhBSp1Tn/s-l500.jpg)

I really don't want to run over it with my tractor.

 ;D   Al
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 17, 2016, 06:40:25 pm
In looking at the IPL you're probably going to have to remove the muffler and "air guide".Other than that all I can tell from the drawing are 4 cylinder bolts .
Title: Re: Breaking loose a stuck piston
Post by: RoyM on December 17, 2016, 10:39:49 pm
The 031 is a bear to work on as were most Stihls of that era. IIRC, the fuel tank and air box come off as a unit. The top handle assembly also needs to come off
Title: Re: Breaking loose a stuck piston
Post by: trail twister on December 18, 2016, 05:30:44 am
OK thanks will attempt again as I get time. Dealing with snow right now & the cold with running saws.

 ;D  Al
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 18, 2016, 10:03:07 pm
If that thing is hung by the piston you'll never be able to pull it off unless you have the arms of King Kong .

If it's hung tight above the exhaust port you could shake it the grease gun trick .Below the only thing I can think of  is get the cylinder up above the crankcase if possible then split the cases from around it which would be a chore to say the least .If all that could be done you might be able to shake it upwards with a dead blow hammer or it just might be a lost cause .If it's rust hung you might save it,lean run stuck the piston and likely the cylinder is toast.Then it's off to find a donor because they haven't made that thing in ages so parts are going to be like looking for a hens tooth .--restoring old saws is not for the weak at heart---
Title: Re: Breaking loose a stuck piston
Post by: Al Smith on December 18, 2016, 10:18:45 pm
Maybe I spoke too soon .I just surfed flea bay and there are a zillion parts for  those things,cheap.
Title: Re: Breaking loose a stuck piston
Post by: trail twister on December 19, 2016, 05:37:23 am
First thing I did when I got it home was fill the cylinder with some PB blaster. That is soaking in it now.

 ;D  Al