Stihl 036 scored piston?

Baby Grand · Jul 8, 2012

In my previous thread I got some good advice about what bar & chain I should get for a donor 036.
I may have hitched the cart before the horse a bit. Tonight, I started checking the saw out.
First off, it really needs a new drive sprocket - that thing looks like it must have been throwing
the chain all the time.
I discovered that the plug was finger tight. So I removed the top and aft plastic covers.
The air filter was looking really choked with fine saw dust, so I did my best to lightly brush it off
with a stiff bristled brush.
Then I decided to remove the muffler/spark arrestor(?) - the boxy black stamped sheet metal
thing on the forward end, held on with 4 torx bolts. I got a bit of a shock when I saw the piston.
Both it and the rings look pretty well scored.
But I've never had a chainsaw apart, so I'm not sure if it's toast, or just showing normal wear & tear.
Here's what I saw:

Is it time for a rebuild? It sure doesn't feel very smooth when you pull the cord.
Should I get the NWP Piston and Cylinder Assembly (48mm) for Stihl 036 from Bailey's?
Thanks for all your ideas & helping the greenhorn!

-Jim

s219 · Jul 8, 2012

Looks like the saw may have been run with straight gas (i.e., no oil mixed in). This is very common with chainsaws, unfortunately.

art · Jul 8, 2012

There sure is enough damage, and I wonder if the crank seals are good.

medic1050 · Jul 9, 2012

When I burned out my 044 I found all the parts I needed to find at Bailey's Online. Check them out.

I melted the piston running the saw hot on the hottest day of last july. The piston and rings werre shot but I was able to clean up the cylinder with muriatic acid and Q tips. $5 at a saw shop got the cylinder reamed to re new the crosshatching and $50 for a new piston and rings had the saw was up and running again.

LD1 · Jul 9, 2012

Its toast. But the real question is weather the cylinder is toast too or not?? The first pic shows the cylinder on the intake I think??? And that looks good. But the most wear is always the exhaust side. So... You can either take the jug off, or you can pull the carb off and look to the back side cylinder wall.

The condition of the cylinder makes all the difference. If it just needs a piston and ring, you are looking @ a $30-$50 repair if you do it yourself and thats for a good piston. If the cylinder is toast too......well....~$130-$150 gets an aftermarket kit, and north of $300 for OEM.

Taking the cylinder off is easy, especially since you already have the top-cover off, and muffler off. All thats left is the carb, and plug wire, and 4 bolts that bolt the jug down.

Baby Grand · Jul 9, 2012

s219 said:
Looks like the saw may have been run with straight gas (i.e., no oil mixed in). This is very common with chainsaws, unfortunately.

That was my impression, too.

Baby Grand · Jul 9, 2012

art said:
There sure is enough damage, and I wonder if the crank seals are good.

I think I'm about to find out ...

medic1050 said:
When I burned out my 044 I found all the parts I needed to find at Bailey's Online. Check them out.

I melted the piston running the saw hot on the hottest day of last july. The piston and rings werre shot but I was able to clean up the cylinder with muriatic acid and Q tips. $5 at a saw shop got the cylinder reamed to re new the crosshatching and $50 for a new piston and rings had the saw was up and running again.

That's good information - It looks like I'm doing a full disassembly now. I'll keep the muriatic trick in mind. I have had very good luck with Bailey's for other, tree related stuff, so that's usually the first place I go look, and usually where I buy.

Baby Grand · Jul 9, 2012

LD1 said:
Its toast. But the real question is weather the cylinder is toast too or not?? The first pic shows the cylinder on the intake I think??? And that looks good. But the most wear is always the exhaust side. So... You can either take the jug off, or you can pull the carb off and look to the back side cylinder wall.

The condition of the cylinder makes all the difference. If it just needs a piston and ring, you are looking @ a $30-$50 repair if you do it yourself and thats for a good piston. If the cylinder is toast too......well....~$130-$150 gets an aftermarket kit, and north of $300 for OEM.

Taking the cylinder off is easy, especially since you already have the top-cover off, and muffler off. All thats left is the carb, and plug wire, and 4 bolts that bolt the jug down.

Thanks for the encouragement. I have to keep reminding myself this isn't a Swiss watch - everything seems very simple. I'll do a full tear down. Now I'm hoping the crank assembly didn't run dry for very long, too, so I want to see how it and it's bearings look. And the seals.

Hope it's salvageable. I'd really like to fit this with a .375 24" bar & chain for the odd big tree that needs dropping or cutting up for splitting.

This is actually kind of good - for all the many hours I've spent using saws, I've never serviced one, other than sharpening the chain or replacing the odd air filter or spark plug. It's an adventure!

-jim

LD1 · Jul 9, 2012

Just remember that the piston will ONLY go in one way. Well...I should say it is only supposed to go together one way, because you "CAN" but it together backwards but you will probabally tear the ring out of it and trash the new piston and cylinder if you do. There is an arrow on the piston (or some kind of marking) read the instructions to find out wether it points toward the intake or exhaust. Reason for this ring placement. Saws have a pin in the ring land that prevent the ring from spinning and letting an end "pop" out and catch in the exhaust port. Because a 2-stroke ISNT a smooth bore, and it has ports in the cylinder, where the ends of the ring meet HAVE to stay on a smooth part.

Which brings me to my next point...Make sure you install the ring right.:thumbsup: So it wont rotate.