Seized chainsaw

[alexinPA]

My Husqvarna 570 seized during firewood cutting. No compression. I put atf in the cylinder and waited 48n hrs. Now there's 100 psi compression, good spark bot won't start. Looks like some atf still in the cylinder. Its coming out thru sparkplug hole and muffler when starter is pulled. Not much... I think that's a reason for not starting. Is there way to get it out completely? Anything else to look for?

 

[Snobdds]

Saws seize due to lack of lubrication. Did you run straight gas in it?

 

[jyoutz]

If you didn’t run the proper 2 cycle oil mix in your gas, then your saw is now a doorstop.

 

[alexinPA]

Saws seize due to lack of lubrication. Did you run straight gas in it?

No. Probably overheated

 

[jyoutz]

No. Probably overheated

I have never seen a saw overheat and seize up if running the correct 2 cycle mix. And I’ve been around chainsaws my whole career.

 

[alexinPA]

My Husqvarna 570 seized during firewood cutting. No compression. I put atf in the cylinder and waited 48n hrs. Now there's 100 psi compression, good spark bot won't start. Looks like some atf still in the cylinder. Its coming out thru sparkplug hole and muffler when starter is pulled. Not much... I think that's a reason for not starting. Is there way to get it out completely? Anything else to look for?

Now i'm back to the beginning. Checked compression again and it's only 30 psi. Could it be that some atf leftover in cylinder resulted in high compression in the beginning, but now when it's gone i lost it? Anyway looks like time to replace cylinder/piston assy

 

[alexinPA]

I have never seen a saw overheat and seize up if running the correct 2 cycle mix. And I’ve been around chainsaws my whole career.

Dull chain?

 

[MossRoad]

My Husqvarna 570 seized during firewood cutting. No compression. I put atf in the cylinder and waited 48n hrs. Now there's 100 psi compression, good spark bot won't start. Looks like some atf still in the cylinder. Its coming out thru sparkplug hole and muffler when starter is pulled. Not much... I think that's a reason for not starting. Is there way to get it out completely? Anything else to look for?

If it truly seized, you couldn't pull the rope, and the damage is done. Waiting for it to cool down, and lube in the cylinder might get things free, but there's still going to be damage in there most likely.

Pull the muffler off and look into the cylinder with a flashlight and see if you can see the piston all goobered up before you do anything else.

 

[BnRidge]

Try pulling the muffler and get a look inside. If it's scored, then maybe look into a rebuild. There are a lot of reasons why a saw can be damaged or run hot other than oil mix.

 

[Buggs67]

Dull chain?

I wouldn't think so. A dull chain will just cut like crap.

My buddy siezed his Husky by grabbing the wrong red gas can. Another friend's wife did the same to the leaf blower. Maybe you forgot to add the 2 stroke oil to the gas, or not enough. FWIW I always put the 2s oil in the 1 gal jug and then put in 1 gal at the pump, always 93 octane. And I started using Star Tron in small engines. And the only jugs for gas/oil mix are 1 gallon and all other red jugs are 5 gallon.

Here's an idea for all us 2 stroke users; maybe spray paint the red jug w/ mix in it half flat black. No more mix-ups.

 

[Snobdds]

There are a lot of reasons why a saw can be damaged siezed or run hot other than oil mix.

Oh...

Lets review

A saw can get hot, but if it's still getting gas and oil...it won't seize. The saw is air cooled and the fins are still providing cooling even if it's running a dull chain. Its not like a car where coolant provides the cooling...

A saw siezing is really only due to no lubrication and that means straight gased.

 

[Doughknob]

My Husqvarna 570 seized during firewood cutting. No compression. I put atf in the cylinder and waited 48n hrs. Now there's 100 psi compression, good spark bot won't start. Looks like some atf still in the cylinder. Its coming out thru sparkplug hole and muffler when starter is pulled. Not much... I think that's a reason for not starting. Is there way to get it out completely? Anything else to look for?

You had me fooled there for a bit. "No compression" means the piston moves but you get no pressure at the top of the stroke. You actually mean you could not even move the piston, right?

Dull chain?

Nope. My neighbor and I are the kings of dull-chain sawing and we, also, have never seized an engine. Sooted up the mufflers, seized chains to bars, threw chains.......... but never seized an engine.

 

[BnRidge]

and that means straight gased.

Or, carb set too lean, leaking crank seals or gaskets, broken internal parts such as rings, a rod snap ring that comes loose, flaked nichrome finish maybe from a previous rebuild, carbon buildup. What are some others, electronic control malfunctions, air filter plugged - . It's got low compression, get a look, diagnose it, fix and try to keep it from happening again.

 

[MossRoad]

A gas 2-stroke engine seizure can be from overheating, improper gas/oil mixture, lean condition, restricted exhaust (causes overheating, too), cold start to full throttle, some part getting sucked through the cylinder or crank case, several issues.


For example, start that cold engine at full throttle. RPMS go through the roof, the piston heats up and things expand faster than the diameter of the cylinder and PINNNG! you're saw is seized. You had the proper fuel/oil ratio. You had the proper air/fuel ratio. You had proper lubrication. You still seized the engine.

 

[Snobdds]

In the first post, he said it siezed during cutting.

 

[MossRoad]

Improper piston/ring/cylinder wall clearance, too.

 

[jyoutz]

A gas 2-stroke engine seizure can be from overheating, improper gas/oil mixture, lean condition, restricted exhaust (causes overheating, too), cold start to full throttle, some part getting sucked through the cylinder or crank case, several issues.


For example, start that cold engine at full throttle. RPMS go through the roof, the piston heats up and things expand faster than the diameter of the cylinder and PINNNG! you're saw is seized. You had the proper fuel/oil ratio. You had the proper air/fuel ratio. You had proper lubrication. You still seized the engine.

After 40 years of working around loggers I have never seen or heard of such a thing. Everyone starts and runs full throttle during cold or warm weather. The only saw motors I’ve ever seen seized was due to lubricant failure.

 

[Root Cause]

I had a tree sit on mine last year. It seized up and I don't think lube had much to do with it. Just sayin'

 

[Snobdds]

I had a tree sit on mine last year. It seized up and I don't think lube had much to do with it. Just sayin'

I think the tree sitting on it had everything to do with it.

 

[ericm979]

Moss's list is right. "Cold seizure" is possible on two strokes. It's not common though. The piston will have characteristic scoring on four places where the thick part of the piston that holds the wrist pin ends.

In this case it's not the cause since it seized while cutting. No oil in the gas, running lean due to poor carb adjustment or an air leak, debris or failure of an internal part, and stuck rings are likely causes. If running a dull chain got it really hot then you'll see evidence on the clutch side. It's possible to overheat the clutch side bearing and seal and damage them but that's rare.

Remove the muffler and the plug and turn the engine to where the top of the piston is at the top of the exhaust port, and then take some good pics of the piston skirt. Most seizures have the damage on the hotter exhaust side.

The ATF will help seal the rings when doing the compression test, giving a false high reading.

It is possible to seize the engine without it locking up. It's not really a seizure of course but the piston and often cylinder are damaged just the same. Or sometimes it will lock up and then free itself moments later, still damaged.