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View Full Version : What chewed up the piston?



BadAssPerformance
03-25-2006, 10:46 AM
Ok, I got this '87 T-top Shelby Z parts car and just pulled the motor out of it. Just curious what everyone thinks might be the cause of destruction to #2. My first guess is that something got in there, Russ (mini-mopar) saw it and thought maybe detonation... the tip of the spark plug looks to be intact and everything tho. So what chewed up the piston?

Here's all 4 slugs:

http://www.badassperformance.com/misc-pics/t-top_all4.jpg

#2:

http://www.badassperformance.com/misc-pics/t-top_%232.jpg

and the head:

http://www.badassperformance.com/misc-pics/t-top_head.jpg

GLHSKEN
03-25-2006, 10:49 AM
THere are no chunks of metal missing... I've seen 2.5's do that after a chunk flies out.

Is it possible it was an older spark-plug that was removed?? Possibly something from the intake tract or dropped down the plug hole during a change??

That's too much for detonation.

BadAssPerformance
03-25-2006, 10:53 AM
No history on the car, so yeah, it could have lost another previous plug...

Also, I havn't waved a magnet over the carnage yet to see if theres something in ferrous in there.

yeah, I'd say it looks like a lot for detonation, but I luckily havnt seen that too many times before. *knocks on wood*

jckrieger
03-25-2006, 12:43 PM
That definitely looks like something fell into the cylinder. My dad dropped the identification tag from the carburator into the intake manifold without realizing it and it was sucked into one of the cylinders. The motor only ran for a few seconds, but the top of the piston already looks like your pictures above.

With that said, I have pictures just like that from running lean at 18psi. (bad +40 injector) I'm betting the cause was debris though. Just grab a polishing wheel and she'll be good to go :)

BadAssPerformance
03-25-2006, 01:23 PM
lol, might need some JB weld before polishing tho...

turbovanmanČ
03-25-2006, 03:03 PM
Definately foreign object in the cylinder. Looks like my old 2 stroke dirtbikes when the piston lets go, :(

shadow88
03-25-2006, 03:39 PM
I agree on the clunk of crap in the cylinder, but don't overlook that "seems awfully advanced to me" ignition timing.

PUNKSLIP
03-25-2006, 09:33 PM
In the military we called that FOD, Foreign Object Distruction.

John

pooky
03-26-2006, 12:10 AM
Did you bother with a compression check before disassembly? That looks like a broken ring.

BadAssPerformance
03-26-2006, 12:41 AM
yeah, I didnt do a compression check... it had been sitting for a while so i was delighted that it even turned over by hand, lol.

johnl
03-26-2006, 03:09 PM
Could be detonation on the theory that it is in the quench area and once you get rough patches detonation will feed on, or is precipitated by, the sharp edges that get hotter because they are sharp. Sort of a viscious circle gets going. Just a theory.

BadAssPerformance
03-26-2006, 04:21 PM
update... my magnet found a small (read: 1/8" cube) of steel/iron in that cylinder. I'll try to get a picture of it.

...too bad I had the magnet out cuz I was fishing the damn 10mm combo wrench out of the inner 1/4 panel cuz I dropped it in there removing the pass side spoiler end :banghead:

jckrieger
03-26-2006, 06:43 PM
I lost a 15mm socket in the unibody somewhere in my old Lebaron while removing the driver's side motor mount. It happened right after I said to myself "I'd better not drop my socket down there".

Turbodave
03-28-2006, 08:01 PM
I lost a 15mm socket in the unibody somewhere in my old Lebaron while removing the driver's side motor mount. It happened right after I said to myself "I'd better not drop my socket down there".

Done that before, now I take off the 3 bolts from the mount to the trans instead, much easier.

GLHSKEN
03-28-2006, 08:04 PM
Done that before, now I take off the 3 bolts from the mount to the trans instead, much easier.

+1!!!!!!

3Bar_Mopar
03-28-2006, 09:14 PM
Dropped a spark plug down between the timing belt and oil pump gear yesterday...the lower cover was still there, so it was a B to get back out!

deuce dodge
03-28-2006, 09:45 PM
ahem........just a wild guess but if the rod bearings shot the piston might be hitting the head...now maybe you already checked that...

deuce

firebaron90
03-31-2006, 02:15 AM
GO out on a ledge here........Injector tip???