Davidov
ArboristSite Lurker
What causes a piston to be like this around the edge?
What is it?
- Thread starter Davidov
- Start date
Help Support Arborist Forum:
cus_deluxe
Commie Satan turd
detonation from ****** fuel would be my first guess
Preignition which leads to detonation maybe.[emoji848]
Did it have a crap load of carbon in the ‘squish’ zone?
The carbon acts as a glow plug.
Did it have a crap load of carbon in the ‘squish’ zone?
The carbon acts as a glow plug.
Davidov
ArboristSite Lurker
Yes it did.on top of the piston also.it was like it was baked on.
Davidov
ArboristSite Lurker
Attachments
I had a 288 project like that one time. Did your saw happen to have any welding done to it?
Davidov
ArboristSite Lurker
No
That's an interesting failure. Any chance on some pics in the intake ports and exhaust port??
Yes Brett, This one is quite unique for sure. The uniform shape of the heat pits and mainly concentrated on the cylinder roof and piston OD. It makes you think fuel additive.
You could be right sir. I just find it interesting that it doesn't follow the flame path across piston top. Just like detonation or preignition failures follow.
cus_deluxe
Commie Satan turd
engines with actual pre-ignition goin on just dont live very long, not nearly long enough for that type of damage. pecker tracks like those in the squish band is from detonation. i have several pistons like that ive taken out of saws. its fairly common with old ****** gas. pre ignition and detonation are two completely different things
Rob Stafari
ArboristSite Operative
Some potentially helpful reading material...
Agree with Cus. Preignition issues normally relate to timing. Detonation normally related to a ignition of combustion due to carbon hotspots. While everyone might not agree they are two different symptoms.
That one looks like detonation .
I had a saw come in that had some welding done to muffler by owner. Man you can tell the difference big time.
I had a saw come in that had some welding done to muffler by owner. Man you can tell the difference big time.
trappermike
ArboristSite Guru
I'll tell you what it is-your engine is throwing lots of small engine particles which is getting hammered in the tight "squish" area on top the piston.-These are hundreds of "dents",from small metal debris,probably from the bottom end,a bad crank bearing. Maybe you can rebuild the bottom end before the piston is beaten to hell. Lots of small metal debris is being pumped up into the cyl. where the piston is pounding it up in the tight squish area. It's not detonation but debris pounding up the piston squish area. Rebuild the bottom end,hope piston is still ok.
