Audi A4 3.0 TDI catastrophic engine failure

Hi!

In my Golf Mk4 build thread I already wrote that we had a catastrophic engine failure with our 2005 Audi A4 (B7) 3.0 CR TDI. As I was driving on the Autobahn with ~ 150 kph, I had to take the foot off the go pedal because of an upcoming 120 kph-zone. At that moment, the engine stalled and wouldn't start again. At the time the failure occurred, there were no warning lights on, no high temperatures, no smoke, nothing.

So we took the car to a shop and used an endoscope to look inside the cylinders. The left cylinder bank showed serious wear / damage, so the decision was taken to take the engine out of the car and disassemble it. After the cylinder head on the left hand cylinder bank was removed, I took the following pics:


The glow plugs. As you can see, the tips are completely burnt down. Obviously the debris fell into the cylinder and cause further damage.


The cylinder head. You can see at least two damaged valves; valve seats are broken as well.


Detail pic





Cylinders and pistons. You can see the damage cause at all three of them. Fortunately, the crank case is not cracked, but there are signs that some of the leftovers of the glowplugs worked their way through between piston and cylinder.


Detail pic of the worst one.

Our way ahead will be to get an entire new crank case with crank shaft, pistons, rods, cylinder heads incl. valves etc. I hope the turbo didn't suffer; the compressor side looks fine and it still turns well. But knowing that some parts of the glowplugs might have gone through the turbine side gives me a really bad feeling.

It looks like there was a serious thermal problem on the one cylinder bank. Surprisingly the other one is fine. I've read about glowplugs melting down in 3.0 CR TDIs; seems like a not-so-unusual problem

The end of the game is that I have to put around 5k Euros into the car to get it back running. Boring and honing the crank case is not really an option as the car belongs to my Missus and she wants the car back ASAP. I don't have to hand the broken engine back to the dealer I get the new parts from and I think if I should keep it and maybe use it for a future whatsoever project.

Greetz,

Fabian

Ouch.
Did you lose your oil squirters on that bank, causing loss of cooling?
Or do you think you had fuel streaming (instead of atomizing) from your injectors?

I don't know about the oil squirter yet, but I suspect the injectors to be faulty. They have been sent to a specialized company for testing as Audi can't do it. I found some info about those "1st generation" CR injectors that says they tend to drop. But usually I would expect the pistons to look even worse.

I would find it hard to believe that such small piece of glowplug were the root cause of the damage to the exh valves.. seems like major injector/railpressure problem, at such low load as youre describing it would be able to survive without oil squireters imo

New engine is in and running. We used a new crank case, new injectors, cyl heads etc. The engine idles a lot smoother than it did before the failure; I assume there was something going on already. Some minor issues to sort out; the new nozzles needed to be "reported" to the ECU by entering a specific code. We also found a minor crack in an exhaust manifold which causes a slight exhaust gas smell inside the car when waiting at a traffic light. This will be fixed today as well.

Despite the minor issues, the car is back on the road again. After inspecting the broken engine we came to the conclusion that some massive thermal problems must have occured on the left cylinder bank - funny though, there was no increase of water or oil temperature at the time the failure happened.

Glad to hear you are back on the road.

I've been reading through your Golf build up thread. I understand how things come up. This summer, I was all set to fix my boat so I can get back to fishing, when the AC in the truck went out. Got to have AC in AZ summers! Anyway, it put about a 2 month delay into the plan.

Tony