Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: Remington on December 10, 2012, 08:29:03 pm


Title: Stihl 036 Pro with crracked piston
Post by: Remington on December 10, 2012, 08:29:03 pm
I was doing a complete tear down and clean up after realizing it was running like crap and I came across this disappointment seen in the picture.

Is this craccked piston normal or a rarity?  One side seems more worn as well. Should I get a new piston or a piston and cylinder.

I also can't take the flywheel off and the casing doesn't want to separate. Does anyone know how to take the wheel off without hammering it. I don't have th e special thread tool and my puller is too wide to fit in the casing.
Title: Re: Stihl 036 Pro with **** piston
Post by: 660magnum on December 10, 2012, 09:33:36 pm
Pistons eventually wear thin on the skirt and if run long enough they break.

You may not need a new cylinder if the chrome is not worn through?

It some times helps to have someone help you get the flywheel off? leave the nut on the threads but loose. I tap with a soft hammer while someone is prying with a couple big screw drivers underneath the flywheel. warming it up with a heat gun helps.

Warming the bearing pocket on one side helps to get that case half off the bearing.
Title: Re: Stihl 036 Pro with **** piston
Post by: Cut4fun . on December 11, 2012, 06:55:06 am
Stubborn flywheels I have learned to spray both side and let soak in PB Blaster for a night.  On stihls I have the tool for that one homemade by Al Smith and they are like $20 $30 OEM on feebay.
Title: Re: Stihl 036 Pro with **** piston
Post by: Remington on December 11, 2012, 10:08:44 am
I think I will just spray it and hammer it off. I don't have access to a welder to make the tool. It would be nice if I can find a threader bar with a thread on the inside as well but I don't see that anywhere.

Cylinder looks fine. Almost no wear inside.

Thanks
Title: Re: Stihl 036 Pro with **** piston
Post by: Al Smith on December 11, 2012, 10:54:51 am
I think the internal threads are M22 by 1.5 which are metric bango fitting size for hydraulic tubing .They made a puller for MoPeds which has both sizes for Stihl .

I think the larger size is M26 for 084s' etc which I can't find in tubing sizes or I'd have made a few of them as well .

You can often thump off a flywheel  with a block of hard wood and a hammer just do so carefully .Don't ever thump on the wheel or the shaft directly with a metal hammer .

I might add on this heat to the bearing pockets on flea bay as of yesterday there was a used Milwaukee industrial heat gun cheap which is what I use to apply heat to a saw engine if needed .They put out something like 1000 degrees .
Title: Re: Stihl 036 Pro with **** piston
Post by: Remington on December 11, 2012, 12:23:01 pm
Do you know where I can pick up a thread for it ?  Is it a plumbing part or gas fitting ? 

 I have some time until the cylinder comes so I might as well play around with and try to get it off in one piece. 
Title: Re: Stihl 036 Pro with **** piston
Post by: Al Smith on December 11, 2012, 12:31:46 pm
What I used were hydraulic fittings I found at work .If you have to buy one you're just as well to buy the puller to begin with  as the cost diff if any would be small .You might try flea bay or just Google it .
Title: Re: Stihl 036 Pro with **** piston
Post by: Cut4fun . on December 11, 2012, 01:12:07 pm
http://www.ebay.com/itm/STIHL-FLYWHEEL-PULLER-KIT-NEW-MANY-SAWS-/230553151043?pt=LH_DefaultDomain_0&hash=item35ae09e643
Title: Re: Stihl 036 Pro with **** piston
Post by: Remington on December 11, 2012, 07:24:25 pm
I took the old wagner paint stripper to it and after heating it up it came off with a wood block. 

I still can't get the casing apart. There is nothing left but the gasket and the thing is still frozen. should I be tapping it and heating it up. I guess the seal is the only thing holding it at this point. I was hoping to remove the flywheel and reveal a screw but no such luck.



Title: Re: Stihl 036 Pro with **** piston
Post by: 660magnum on December 11, 2012, 07:44:08 pm
The bearings are pretty much size for size on the crankshaft.

The bearings are cold when they are set in a hot crankcase.

That is what's holding it together.
Title: Re: Stihl 036 Pro with **** piston
Post by: Remington on December 11, 2012, 07:46:22 pm
So what does that mean for the average home user. Does that mean I can't take it apart without special tools or do I just have to hammer it a little harder.
Title: Re: Stihl 036 Pro with **** piston
Post by: Al Smith on December 11, 2012, 08:09:19 pm
Looks to me like 5 case bolts .Three around the actual crankcase and two on the oil tank .
Make certain you get all of them .Heat the bearing pocket and just tap the crank with a rubber hammer ,wooden /rawhide  mallet not a 4 pound brass hammer .You could most likey get enough heat out of a hair drier .

If you get to thumping it like you are driving a railroad spike all you'll do is damage the bearings .
Title: Re: Stihl 036 Pro with **** piston
Post by: Cut4fun . on December 12, 2012, 01:37:48 pm
I have never had a pro stihl split before. But on the metal crankcases of the husky poulan etc. After removing all the bolts and it still wont budge. I take a rubber hammer and tap at first then hit harder on the bottom of crankcase where the flywheel well is outward till the seal is broken. Has worked every time I have tried it.
Title: Re: Stihl 036 Pro with **** piston
Post by: Remington on December 12, 2012, 02:27:04 pm
I'm almost finished. It moved now and one end has separated about 1mm
Title: Re: Stihl 036 Pro with **** piston
Post by: Al Smith on December 12, 2012, 06:36:02 pm
Well truth be known a lot of people have problems with a case split .It's just one of those tasks that once you get the hang of it it's not too bad .
Title: Re: Stihl 036 Pro with **** piston
Post by: Remington on December 17, 2012, 12:02:09 pm
It wasn't so bad. I just didn't want to damage it. I was tempted to put the flathead in there and give it a hammer but I did that once on my bike and she never rode again.