2008 Audi Q7 4.2

Driving down the freeway @ 70mph, the check engine light flashes several times as I feel a little vibration. Engine was running, couldn't hear a sound, exited freeway. Engine was missing, not overheating, turn into empty parking lot and could hear a small clicking with engine missing. Turned off the engine, called AAA.

I dropped the complete engine and trans in my garage, and ripped it all apart to see a completely destroyed engine. (I have pics) Sad day. 95,000 miles, Timing chain and all components were in perfect shape. I have no idea why this has happened.

Has anyone heard of this kind of failure in the 4.2l?

 

I assume really dead forum?
Would anyone suggest a more responsive forum to share my problem?

 

This is the first time Ive seen a stock motor suck a valve like that. it look to me like your the valve spring broke and then the keepers came loose. The only other times Ive seen this happen is when the cams are upgraded but the rest of valve train is not. This puts a lot of extra stress on the springs causing them to brake.
The only cause I can think of for one to fail in a stock application would be a faulty spring.
I know this is not very comforting.
On the plus side if your cylinder wall is not scorn to badly you should be able to just replace the piston and the head on that side and put it back together.

 

Yep.. The broken valve spring is an important clue. Like mentioned above, when the spring went, the keepers came loose. Spring tension is what holds them in. Once it got dropped, the damage was done.

How it didn't poke a hole in the top of the piston, I'll never know. I bet the rod is bent. I'd replace the crank and rod bearings since the oil clearance has surely been wiped/disturbed to the point to where the bearings on the bottom end have run metal to metal due to the mechanical interference of the valve getting chewed on...

The cylinder wall looks pretty bad and I think I see a slight gouge down about 5 o'clock. Not really looking good for a rebuild in that shape.

 

Yep, Block is no good, and head is irreplaceable.

Audi tells me to beat sand, didn't expect much, maybe help by 50%, but I didn't even get offered 10% off a new long block. This will be my last, I've had 3, 2 were great, well over 200,000 miles then sold. The 3rd, I love, but Audi sold me a lemon! I hope others don't experience such a setback! Be WARNED, there may be inferior parts in your TOP END engines, and Audi doesn't seem to care!