Did I just catch this piston before it exploded?

[Vintage Engine Repairs]

Just finished cleaning this Stihl 045 piston, top is dented, underneath is protruding and cracked. Is this caused by detonation? Did I just catch it before the saw would have shot a piston?

If it needs replacing I’d want OEM wherever possible. Looked for meteor as second option with no luck, but Tacsum came up, never heard of them, can anyone advise as a last resort? Is it also Italian made?

 

[Jasent]

I may have a piston for you. Also new badge if you need it. I’ll check after work.
Is it 045 av or 045 av electronic?

 

[holeycow]

That's not detonation. That's odd. It's a faulty piston run slightly lean in long cuts, I'd say.

 

[Vintage Engine Repairs]

I may have a piston for you. Also new badge if you need it. I’ll check after work.
Is it 045 av or 045 av electronic?

Thanks mate! Just the piston 50mm for 045 AV (points)

it’s the one with two different size rings.

I have a guy here in OZ who may have one, if he doesn’t then sure I’d buy one from you. Are you in the states?

how much would you want?

 

[Vintage Engine Repairs]

That's not detonation. That's odd. It's a faulty piston run slightly lean in long cuts, I'd say.

Hey mate, no damage or scoring to the piston other than what you can see. Still had great compression, skirts were nice - not worn away.
Plug was a nice colour etc. I don’t think it was ever run lean. Hmm

 

[holeycow]

could be a combination of poor metal and excess heat in the crown. Or even phsical damage..piston stop? Or all of that. It's an odd failure.

absolutely no detonation tho, as that shows up as pits on the exhaust side top edge first.

 

[Mad Professor]

I don't think that would have exploded. At worst spit out a small piece of aluminum and lost compression .

Looks almost as if someone used a long reach spark plug, with out a ground electrode, as a piston stop.

 

[Northerner]

I say piston stop as well. Seen it before.


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[rogue60]

To me it looks like piston stop damage?
Rope prevents that kind of damage.

 

[Mad Professor]

I wonder if you could TIG over that and keep the piston?

 

[SteveSr]

Just finished cleaning this Stihl 045 piston, top is dented, underneath is protruding and cracked. Is this caused by detonation? Did I just catch it before the saw would have shot a piston?

If it needs replacing I’d want OEM wherever possible. Looked for meteor as second option with no luck, but Tacsum came up, never heard of them, can anyone advise as a last resort? Is it also Italian made?

Don't know the plug layout on that saw... Possible piston stop damage? The damage is slightly off-center.

 

[grizz55chev]

Just finished cleaning this Stihl 045 piston, top is dented, underneath is protruding and cracked. Is this caused by detonation? Did I just catch it before the saw would have shot a piston?

If it needs replacing I’d want OEM wherever possible. Looked for meteor as second option with no luck, but Tacsum came up, never heard of them, can anyone advise as a last resort? Is it also Italian made? View attachment 898099View attachment 898100

JB Weld it!

 

[Vintage Engine Repairs]

Don't know the plug layout on that saw... Possible piston stop damage? The damage is slightly off-center.

 

[SteveSr]

View attachment 898156

Confirmed... Piston stop damage!

 

[Vintage Engine Repairs]

I have seen these Stihl metal piston stop tools pictured in their service manuals. WTF were they thinking?

 

[Jasent]

If I do just cover shipping. Do not have rings

Thanks mate! Just the piston 50mm for 045 AV (points)

it’s the one with two different size rings.

I have a guy here in OZ who may have one, if he doesn’t then sure I’d buy one from you. Are you in the states?

how much would you want?

 

[Vintage Engine Repairs]

If I do just cover shipping. Do not have rings

Wow that’s really generous, thank you! Could you tell me if the ring lands on the top and bottom are different sizes (my piston it is - the top is a smaller ring).

also, could you measure the diameter of the holes that the wrist pin sits in? Just trying to make sure it’s going to work.

Thanks so much again, your generosity is much appreciated.

 

[Kenskip1]

My .02 cents. If this was done with a piston stop how could you prove this? Obviously the piston was installed in the saw. If someone had used the piston stop then they should be aware of this. In short, you could never tell with the piston in the saw.

 

[holeycow]

?

The piston stop could have been used without ever looking at the piston afterwards. That damage could even be missed in a superficial inspection of the piston in-hand.

 

[Vintage Engine Repairs]

Here it was before cleaning - easy to miss as it’s covered in carbon.