Nice "lightweight" piston

[metalman]

Here's a #4 piston I just pulled from a 99 motor. Nice eh?
I drove the car about 100 miles and it ran like a top, sold the engine to a friend then it started making noises. I gave him his $ back. I think the piston was deteriorating the whole time. Heat 'exhaustion' perhaps?? Ben, ever see these on #4? The rest of the parts look fine. Cyl walls are good.
Anyone need a block? Crank? :lol:

[attachment=136]

[amaff]

well there's your problem!

[metalman]

LOL...pretty sure about that??

Engine had 80k on it so it wasnt from excessive mileage.

[ben91]

Dang. Was that car forced induction?

[metalman]

Dang. Was that car forced induction?



Nope. Just a plain old street driven stocker.
Owned by an older fellow.

[Stealth97]

are you positive the rod is straight? would not take a whole lot for the skirt to hit the counterweights on the crank.

gave his money back? good for you man.

[metalman]

The rod appears straight to the naked eye.
The rotating mass in the shortblock assy turned nice and free and seemed fine too when assembled.
Whe running the noise sounded like a wrist pin and indeed, it was related!
I see a mark or two on the counter weight but nothing real conclusive to my eye.
Just the skirt pieces dropping off at XXrpm could cause some marks.
There are a couple marks in the area of another cyl counterweight too.

[Stealth97]

I would guess just a defective piston...

[amaff]

that's crazy. Had it ever been overheated? I've seen #4 piston problems on miatas before, but never quite like that. It didn't burn, it wasn't smashed, it looks like a clean break. It COULD just be a factory defect...

[metalman]

Not knowing all the history of the car I dont know if had ever been overheated or not.
The owners had reciepts for various service items done and everything looked normal there.
Another tidbit...looking at the top of the piston, the #4 had the least carbon buildup of any, almost none.

[ben91]

lack of carbon points towards HG. broken *** piston points to... I dunno

[amaff]

Exactly... broken HG can lead to over-heating, and at least in the early miatas (I'm not terribly familiar w/ the NB motors), Cylinder #4 was the one most prone to suffer damage from heat, but usually only in F/I applications. Though, if it overheated at some point in its life, I can see that piston being weakened and, though it's a stretch, eventually falling apart.

[Jack-MX5ATLanta.com]

:jawdrop: god damn

[RotorNutFD3S]

Wow! I'm glad that didn't happen to my piston when rod #1 bent and the piston and counterweight "contacted" each other.

[BFH miata]

I gave him his $ back.


reason number 596 why to buy parts from metalman...

[Otto]

im waaay to paranoid to have come into this thread as a 99 owner:cry:

and if you wanna give away the block and crank ill take it!:P

[MeFryRice]

I gave him his $ back.


reason number 596 why to buy parts from metalman...


That is awesome for Kirk to do that. Most sellers would be like, "your **** outta luck bud!"...

[ToddN]

I gave him his $ back.


reason number 596 why to buy parts from metalman...


That is awesome for Kirk to do that. Most sellers would be like, "your **** outta luck bud!"...


I think we know why you and Sawyer stick to screen names now. :D

[RotorNutFD3S]

Damn, someone beat me to it. lol

[Sawyer]

Haha nice!

[metalman]

I just want to be clear that the Captain of the Starship Enterprise had nothing to do with this engine or any related transaction. :P :lol: