Piston Failure??? Stihl MS362s

[HarleyT]

More Photo Evidence

Aluminum bubbled on the bottom side of the piston. Metal transfer damage on all sides of the piston.

Straight gas.....

 

[HarleyT]

Metal transfer damage on all sides of the piston

 

[pioneerguy600]

Thanks, there has been a wicked heat buildup on the exhaust side , difficult to tell what is the cause from here.

 

[ericm979]

The last piston does not have the massive detonation damage on the crown like the others. Death ash is from overheating. The seizure marks look like overheating too.

With the detonated pistons the question is: is the detonation the primary cause of failure or was overheating the primary cause and it caused the detonation?

 

[dmb2613]

thanks, we are a Stihl dealer

 

[dmb2613]

Only operator errors I know of that could cause this is are covering the vents on the starter cover, really long cuts with a dull chain, or getting it jammed holding it wide open til it fails.

I expect the muffler was blocked while cutting. I don't think you could run it lean enough to do that without locking up first

 

[MrWizard]

thanks, we are a Stihl dealer

Very nice.

 

[buzz sawyer]

Subscribing. I thought Stihl recommended at least 89 octane?

 

[MrWizard]

Thanks, there has been a wicked heat buildup on the exhaust side , difficult to tell what is the cause from here.

extreme heat, still can't understand how someone wouldn't feel the type of heat this thing was putting off. was hot enough to melt the plastic, don't think i would have held on to it for too long.

 

[MrWizard]

Subscribing. I thought Stihl recommended at least 89 octane?

stihl does. so i had a meeting with one of their main guys, he's going to allow me to rebuild another saw and then at my recommendation only run 93 octane. this saw will be placed in the hands of a guy with over 10+ years of experience. we have to find out is this being done intentionally or is there an issue somewhere with their fuel, etc.

 

[BangBang77]

I manage a large team (100+) of industrial maintenance employees and engineers; from apprentices to journeyman millwrights and electricians to PE certified engineers.

As such, I have seen what mischevious or disgruntled employees can do to equipment on many occasions.

If quality of rebuild and fuel has been verified, I would lean toward intentional damage to the saws.

 

[MrWizard]

I manage a large team (100+) of industrial maintenance employees and engineers; from apprentices to journeyman millwrights and electricians to PE certified engineers.

As such, I have seen what mischevious or disgruntled employees can do to equipment on many occasions.

If quality of rebuild and fuel has been verified, I would lean toward intentional damage to the saws.

I really wanted to have hope in these people. Today, something happened that made me think that what everyone saying foul play is not wrong. Still searching for more answers from them. Would hate to think that someone would deliberately try and do something like that.

The saws were rebuilt by our Silver Tech and I oversaw the testing and start-up.
Everything was perfect, saws initial break in sounded good.

 

[CR888]

Odd things can happen when multiple folks use the same fuel containers too. In a commercial setting god knows how many times they get opened/closed in a day and what is let get inside them. Is this a crew that runs top handles, pole saws, blowers, large bucking saws, limbing saws that drink from the same can & ONLY the 362's have had failures?

 

[HarleyT]

thanks, we are a Stihl dealer

Spiritually, we are ALL Stihl dealers......

 

[MrWizard]

Odd things can happen when multiple folks use the same fuel containers too. In a commercial setting god knows how many times they get opened/closed in a day and what is let get inside them. Is this a crew that runs top handles, pole saws, blowers, large bucking saws, limbing saws that drink from the same can & ONLY the 362's have had failures?

To be specific, the 362 that is the piston is still connected to the saw was destroyed with one tank of MotoMix. Just thinking about How you worded that. Makes me think this is possibly even more intentional than I thought before.

 

[jimrb]

How many minutes is one tank of MotoMix? One tank of mix seems like a short time. Here is a video on chainsaw timing. I would be curious if the timing is too far advanced. I may have miss-read, but it seems like the failing saws have the same ignition modules, flywheels and keys before and after the repairs. Maybe an unknown batch of bad modules with too much advance. I know I am grabbing at straws.


I would be curious to watch a day, or half day in the life of the crew that is going through saws. Watch them mix up the fuel mix, watch them cut.

Is it possible to draw samples of their fuel mix and get it tested? Not likely to be bad fuel if some saws live a day, while others die in a day of work using the same fuel.

 

[ericm979]

Did you check that the plugs are the right heat range?

 

[Sam R]

362 is a pretty new saw in NA, isn't it? Barring some totally improbable condition like Stihl forging a few bad piston/cylinder kits I'd say someone is probably earning themselves a pink slip if not more.

 

[cuinrearview]

Were they working in the vicinity of some sort of emp or magnetic field?

Man, the conspiracy is getting real deep...

 

[HarleyT]

Any Russians working there?