Cerocool

Hey guys...

I need some expert help here. So I bought a 02 A6 w/3.0L (w/146k) a few days ago as a fixer-upper. The guy said it runs but just not good. So I test drive it and it drives but idles really bad and shakes. At higher RPM the motor sounds great. There were no knocks or rattles so I knew it couldn't be internal damage (so I thought.) So I tow it home and run vagcom. Here are the codes I'm getting:

6 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 002 - Lower Limit Exceeded
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded
16690 - Cylinder 6 Misfire Detected
P0306 - 001 - Upper Limit Exceeded
16687 - Cylinder 3 Misfire Detected
P0303 - 001 - Upper Limit Exceeded
16686 - Cylinder 2 Misfire Detected
P0302 - 001 - Upper Limit Exceeded
16502 - Engine Coolant Temp. Sensor (G62): Signal too High
P0118 - 002 - Lower Limit Exceeded

So I thought, maybe its just a bad coolant sensor since they tend to go bad frequently even though vagcom was giving me good readings. I replace the coolant sensor and that didn't fix anything. I still get all the misfires. I then check out all the coils and move them around to simulate a bad one (Cylinder 6 code pops up first always) and that didn't do anything. Also, all 6 of them were just replaced with the recall. I then run a compression test... and wow... something is wrong

Cylinder:
1-105 psi
2-50 psi
3-75 psi
4-110 psi
5-75 psi
6-100 psi

My first thought was that the timing belt jumped a few teeth but come to find out this 3.0 is impossible (as far as I know) to time without the cam locking tool which I don't have, yet. The belt is in pretty rough shape but its tight so I suspect its original. I didn't see any missing teeth or anything. Is it even possible to jump teeth?

I took the cover off bank 1 and the cams don't look abnormally worn just looking at the lobes. Does this engine have VVT and can it cause the timing to be off at idle? It has to be something with the timing because all the cylinders are off and not just one or a bank.

So here are my big questions:
1. Can I check timing without the cam lock tool?
2. Has anyone seen a belt jump teeth?
3. Can the VVT be stuck in full advance and cause this?
4. Anything else I can check?


Thanks a ton!!!

-Paul

Peter Badore

The 3.0l V6 has VVT for all four camshafts. Usually there will be a fault code if the VVT has malfunctioned. I would guess that your engine has bent valves.

Cerocool

I just received the cam lock tools and the timing seems to be in line. I think this engine was overheated because when I do a compression test I can hear hissing like compression air escaping either through the exhaust valves or intake valves.

So now my question is what usually has gone bad? I'm guessing I'll need to get new valves and machine both heads? Do you think that the head or even the cylinder head could have warped? Is this worth even fixing? If I have to sink a bunch of money into this thing I'm just going to sell it for whatever I can get for it.

Arg... what should I do??

SloopJohnB@mac.com

Do a leakdown test to confirm leaks at intake or exhaust valves or just plumb up your compression tester (if you have a set of threaded adaptors) to an air pressure source....you'll be able to tell where the leak is coming from.

jschick

I just finished rebuilding my neighbors 02 a few weeks ago, he had same symptoms and same cyls had bad compression except 1 of them had 0 compression the others were just under 50. he did had bent valves! we did find his belt was missing a few teeth also, but it is also possible for the cam pulley's to move if not tight. I also heard the air leak.
Good news is this really isn't a bad engine to work on and He had less then $1000 in parts, timing belt, water pump, tensioners, gaskets, and valves. Bad news you must have the Timing tools, we had to rent them 2x, once to check it, then again on the reinstall 2 weeks later!
what you can do is pull the intake which will take 20-30 minutes and look at the intake valves. it was easy to see what was bent on his, it was the center intake on 2 cyls, and 1 exh on the other which you can't see till the head is off. you can also spray carb cleaner in the valve to see if they leak!
my guess is with 146k on the car you have 1 of 2 things, either you are missing teeth or the T-belt was changed and they did not torque the cam pulley bolts properly and a cam pulley spun. I was afraid of busting the bolts when I torqued his I think the spec is over 80lbs I think it's 84 but don't recall

Cerocool

Well guys I have found the problem. I pressurized each cylinder at each TDC and found that the rear two cylinders on both banks would leak between each other!! So immediately I knew it was a bad head gasket. Now I did find a lot of other evidence of it being over-heated like the intake manifold melted slightly! I hope it will still seal on the head.

It was a b$#%^ to get this far but I had to take off the cylinder head to confirm my diagnosis and sure enough, the head gasket melted/split between the 2 cylinders! I've never ever seen that. I'm guessing it got so hot that the gasket metal became soft and the pressure blew right through it. Now I just hope the head isn't warped. Crossing fingers.







And the engine bay:

Airbag

Dude get that coolant out of your cylinders .. if it leaks down past the rings to your mains your engine is toast .. er ... more toast ..

Cerocool

Yeah, that was the first thing I did, well after I took the picture

Airbag

so what's the plan .. a couple of gaskets and some valves ? or are you going to send the heads up to check for falet and be redone .. you may even be able to get heads from shokan or force5 at a reasonable price . The issue may ne if the deck is flat or not .. some good pics of the destruction there.

Airbag

look at the bright side ... changing the o2 sensors is a snap now