What causes this??

[Patchman]

You could flush the old engines with diesel, because they were such a loose tolerance as far as  clearances went. Now everything is so tight, it wouldn't be a good idea. Most motor oils are high detergent, and you won't have that sludge problem unless you severely abuse them. When I did repairs for two used car lots, I saw everything imaginable! :smile20:

 

[jdeaton]

I got to go with Patch on this one (as much as it pains me)  If you go to my thread on all the motors I brew up in the Liberator, you will see a picture of a broken piston.  Much like your broken piston.  The machine shop said it looked like detonation or a nitros hit.  Since the motor had never seen nitros, it let us believe it was "cheap gas and WOT applications"  Hope that helps.

 

[SimplyOrange]

head gasket leak eroding the hyperutectic piston.thas why its only in one cylinder

 

[Patchman]

Pains you? You so crazy! crazy.gif :smile30:

 

[jdeaton]

I started agreeing with Henry and that was tragic, started buying boats, I shouldn't.  Figured if I started agreeing with you, I'd start buying project cars.  LOL

 

[Patchman]

I started agreeing with Henry and that was tragic, started buying boats, I shouldn't.  Figured if I started agreeing with you, I'd start buying project cars.  LOL

All true statement! :smile16:

 

[Becket]

The Hole could have been Caused by Detonation (Yellow)

These Squares are Dents, Not Fractures (Red) as well as these in the Dish (mushroomed) (Black)

This looks like the remnants of the culprit, Possibly the Piece from the Hole, added metal to the Piston (Green)

I see no tell Tale signs of a leaking Head Gasket.

 

[SimplyOrange]

The Hole could have been Caused by Detonation (Yellow)

These Squares are Dents, Not Fractures (Red) as well as these in the Dish (mushroomed) (Black)

This looks like the remnants of the culprit, Possibly the Piece from the Hole, added metal to the Piston (Green)

I see no tell Tale signs of a leaking Head Gasket.

ill admit you have a much better eye than me and it all makes sense, i had a blow head gasket eat one up like that before, but after you point it out that way i see what you mean, mine just didnt have the square dents or missing corner piece. but on another motor that lost a sparkplug tip, my damage was evenly spread across the piston.

 

[shimp]

My thoughts are pretty much along with Gas-Holes.

Detonation was likely an issue throughout the engine, as every cylinder had substantial amounts of carbon, like Patch said, will cause detonation as it acts like a builtin heater in each cylinder that it's present.

HOWEVER since this was really the only piston that had damage, SOMETHING had to have gotten in there.  As Gas-Hole said, those are DENTS not fractures. 

The likely hood of something getting in there is 50/50.  It could have been part of a spark plug, or it could have been the piece of the piston that broke loose, and is either missing, or is stuck in the ring grove below what is visible.  The oil ring could have come apart, but since there are no signs of scarring in the cylinder wall, the mysterious solid object that caused the dents most likely was either the piece of the piston itself (random oops from factory when piston was installed, or fractured at some point later) or some piece of the spark plug.

Will pull the piston out today, carefully, and look for anything stuck in the top ring groove ABOVE the top ring.  If nothing there, then I would have to guess more than 50/50 the mysterious object was the piece of the piston itself.

This is fun don't you think?

 

[Devilman]

Not possible it could get blown out the exhaust?

Tore apart a 454 once where one piston had what looked like caterpillar tracks all over the top of it, lol. Cylinder wall was fine though. Engine was sloppily built, so we figured something like a small set screw or something got down there during assembly. After a complete tear down, never did find what made those marks... chalked it up to gettin blown out the exhaust.

Those marks on yours are pretty good sized marks though...

 

[mr rogers]

Shimp, i did some work on a jet last year with a olds in it, that wasnt running right. ended up pulling a head off because it had no compression on one cylinder.the head of one of the valves broke off, banged around on top of the piston doing similiar damage as yours. dented piston a little, but did not hurt the cylinder walls at all. never located the head of the valve, so could only assume it was spit out of the exhaust.

 

[EMBRACETHEHATE]

Seafoam guys, best shit ever. I run it thru my fuel, and oil in my ford ranger. Runs great has 146k on it.

Sent from my DROID RAZR using Tapatalk 2

 

[shimp]

Pulling this piston today.  Ended up having lots to do last couple days and did not get a chance to mess with the motor, will do today and post pics!

 

[Crusader]

Looking forward to seeing what you find Shimp.

 

[shimp]

Who said Top Ring failure?

Pics say it all.

 

[shimp]

Since nothing got past the second ring, there is no cylinder wall damage.  Not even at the top, which is a little surprising. 

My guess is the "good ole boys" that pulled this motor stopped drinking whiskey and rye long enough to do a compression check on this motor after it started "running funny", probably after about 1000 miles or more and this cylinder was major fail so they got another motor from a junkyard and swapped it in.  Hence why some of the accessories were still with the motor, like the oil pan, balancer and main pulley, and some of the engine mount brackets and sensors and valve covers.

And then when they sold it to demonmaestro's dad they didn't tell him it was fubar'd.  Or just told him "i ont know, it jest starded runnin funny"....

 

[HellinnFrnt]

I gots plenty o parts  clap.gif