Dodge 5.7 Hemi carnage:

[speeder]

We have a Dodge Magnum in friend's shop that had a dead cylinder. (#8, rear hole on driver's side). It belongs to old friend of my buddy so he took it in, normally he only works on MB cars and (some) BMWs. After doing the normal diagnostic tests on it, (injector or spark), we did a compression test and it had zero in that cylinder. At this point we were thinking sticking valve guide(?), maybe something to do with the feature that cuts out half the cylinders on the freeway for higher MPGs.

He finally got around to removing the head and this is what he found, (98k mile car):



Anyone want to ID the problem (cause) of this carnage? Maybe someone knows from experience. I'll come back later and see who got it right.

[WolfeMacleod]

Chinese pistons?

[Jared at Pelican Parts]

Broken ring land?

Funny, those heads don't look too hemispherical.

[masraum]

Wow, impressive.

Originally Posted by Jared at Pelican Parts

Funny, those heads don't look too hemispherical.

I was thinking the same thing.

[Porsche-O-Phile]

But it looks mean with those headlights and all. So it's okay.

[wdfifteen]

Something allowed the piston to hit the head and broke the heck out of the ring lands? I doesn't look like it happened on the big end of the rod, so it must be wrist pin related. I'm puzzled by the circular mark on the piston head that doesn't seem to have a corresponding mark on the head though. It looks like the size of a valve seat, but the valves appear to be OK.

[rouxroux]

Slap, slap....yeah, like that....

[masraum]

It's broke.

[recycled sixtie]

the warranty does not cover this kind of damage. Please read the fine print...
How about broken timing belt/chain? But sir you did not replace the timing belt....
Second guess...It's a Chrysler product and is programmed to self destruct at 98k just past the warranty limit... Okay I give up, what is the answer?

[Teutonics]

Is it odd that the damage is only on the sides of the piston and the head? There appears to be minimal damage on the valves, plugs, and center of the head, and light damage in the middle of the piston. That, and it is on both sides on the "weak" sections of the piston.

Broken rings flapping? But in two spots? Weird.

[EarlyPorsche]

Thats a shame. My 4.7 V8 went over 180K without anything but fluids, plugs, and filters until I lost track of it after sale. It is probably still running with well over 200K on it. I know that the two engines are unrelated but I am curious whether you know whether Hemi's usually have problems at that mileage or if this is a fluke?

[herr_oberst]

came from the factory that way?

[nota]

wrist pin clip got out and under the rings

at first I thought a broken sparkplug bit
but the rings look bent and the break in piston edge looks clip sized
and is located right above the wrist pin

[Mo_Gearhead]

The hemi engine design has moved the top compression rings very close to the piston top. I think I read they specially "treat" the piston domes/tops to add strength in this highly stressed area.

Low octane fuel can also cause detonation.

Looks like a part of the piston top separated and bounced around for awhile. That particular cylinder wall must look attractive also?

[speeder]

Broken ring land?



Funny, those heads don't look too hemispherical.

A broken ring land would not cause any of the damage to the head or top of piston you are seeing. Yes, it has a broken ring land. (As well as a lot of other damage). But that is collateral damage and has nothing to do with the cause of all this. I'm looking for the cause. WDfifteen is the only one who has come close. Do you guys need more hints? It's apparently a very common failure on these. That makes it easy for anyone with google.

[pavulon]

valve seat failure

[sammyg2]

I had a real hemi back in the day and broke a piston a whole bunch worse than that. The biggest piece I found was the size of a half dollar.
The rod was sticking out the side of the block and the crank was bent.
It cost $3000 just to save the heads and that's back when $3000 was a month's gross pay.
All that just because I was running 30 over on the blower at around 1.4 bar.

My guess on that one pictured above is from detonation due to bad gas or a clogged injector or such.

[gtc]

Originally Posted by speeder

Do you guys need more hints? It's apparently a very common failure on these. That makes it easy for anyone with google.

It looks like valve spring failures are common, though I still don't see what was banging around inside the cylinder.

[notfarnow]

Originally Posted by pavulon

valve seat failure

that is my pre-google guess too. That mark on the top of the piston almost looks like it corresponds with halft a valve seat that was thrashing around before it got pulverized. Looking at the picture of the head, it almost looks like one valve is sitting lower, without a seat

[notfarnow]

and google supports the theory... "hemi valve seat":
Another Hemi with a failed valve seat (pics)

That's the universe's punishment for buying a stupid looking car (says the guy who owned 7 LeCars)