onefastviking

Sorry, Just saw this response to my previous comment.
No, a rod thru the side means a new case. But Porsche still stands behind it for it's core value and there are many other potential good "core" parts in the complete motor assembly as they come to warrant them doing it. Remember that some come with Alt. AC compressor, then oil pan, etc etc etc .

Gary R.

Chris - this is over a year old, look on Page 1 for pics of the grenaded motor..

Chris M.

I was wondering what he found if/when he split the case as he said he was going to on page 1.

38D

Pictures of the failure below. What I believe happened is the wristpin pulled out of the piston. The rod then rode "solo" until its bottom end failed and went out the top of the case.

txhokie4life

Which piston was this?

I believe its the drivers side which has the blind wrist pin lock assembly procedure.

One of the trickier aspects of the M96 engine rebuilds.

If that did not seat properly you could get a failure like you described.

mike

J richard

you can certainly see the "solo" ride up and down the cylinder wall...

So if I get this right?...

1. D Chunk failure
2. Piston jambed/split on the chunk on the downstroke and pin ripped out of the piston
3. Rod/Pin go "solo" and hammer the crap out of the remaining piston parts and cylinder wall
4. Rod fails and goes through the case

thats pretty frigin ugly...my box has a factory reman motor in it, god only knows if its one thats prone to this failure...

Chris M.

Thanks for the update. What did you replace it with?

38D

Drivers side front (#4 I believe).


That is one scenario, but I'm not sure if the missing bits of cylinder happened before or after the wrist pin pulled out. The missing chunks are the right size that the rod could have just pounded them out.

When I was driving the car, it went "flat"; felt just like breaking a rocker. There was no bad sounds at this point. I got off the throttle, and was idling down the track. Then there was a sound and lots of smoke. I turned off the car, and coasted to a stop.


Another 2.5L (its a Spec Boxster)

J richard

Just trying to figure out how the pin boss of the piston could fail without some serious "help", that's a pretty tough hunk of metal. It didn't drop a valve, they're intact, if you holed a piston it normally would just go limp and smoke... just playing sleuth about the fail points on these motors, either way not much in the way of prevention...

txhokie4life

The picture is not showing a DChunk failure.

In that case the liner literally starts cracking at the top near the heads
and eventually works it way all the way around the cylinder in a semi-circle.
More of a D oval look -- thus the name.

The crack goes all the way through the cylinder wall. It then can separate and
become flying debris in the combustion chamber.

Symptoms can be oil in your coolant. Coolant filling the cylinder when hot, or only at start-up.
Misfires at start up or later (due to the coolant in the chamber).

I thought I might have a picture of a D-chunk -- but I don't on this computer.

However -- he is a start of one on top -- this was a '04 3.6 and you could catch your finger nail on it.
We had bored out to 3.8 with JE pistons as can seen below.

Mike

38D

Pictures of D chunk failures.

Werkstatt

Couple photos of sleeve dropping.

txhokie4life

Hope we're not scaring the SPB folks away!

m

38D

It really shouldn't. My engine had 120,000 street miles on it before I started racing it. It had lived a hard life. I replaced the engine with a used one, which cost me 4k installed (granted I did the install myself). With an accusump and decent oil, I expect this one to last a while since its in much better shape than the prior engine.

Rick DeMan

Thats a great price for a great engine..