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

 

The low compression is likely causing the problem. If these numbers are accurate, my guess is your engine needs a piston ring or valve job or both. None of the cylinders is within correct working range. Before you go any further, have a competent tech do a leakdown test and read the intake vacuum with a meter to confirm the diagnosis. This may souynd lke heresey, but I have a friend Jag tech that swears by the oil additive called "Restore" that may give your engine back some life. With a fixer-upper, it would be my first thing to do, although I would not take this car out of town.

 

If the timing was the issue, you would either have the same low compression readings across all cylinders or you would have 0 compression where the valves touched the pistons. I would suspect the engine was overheated at some point. Time for a leak down test.

Good luck,

Bob

 

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.

 

Engine seems worn out, did you pull a carfax to verify if the mileage is correct? Some one might had use a program to turn back the mileage.

 

The only way to know how bad it is is to tear it down and pull the heads. Put a straight edge across the block if the block is good and cylinder walls look OK. Then order a couple re-manufactured heads. Check online there is a place in Sarasota or Tampa Florida that has them at a decent price last time I searched. But maybe you'll luck out.

Only you know if it's worth it.

 

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.





I dont think you are supposed to see light through this!!


And the engine bay:

 

WOW, simply WOW.

 

You've paid $5 for that car?

 

Look for a new/used intake manifold.
Try Shokan.com or any junkyard.
Mine was a pita to seal and it was in good shape!!!!!!!
It kept leaking through the bolt holes I finally used Indian Head on the whole thing and permatex on each bolt and it sealed up.

How is the block surface and heads Straight or warped????

Use some Indian Head gasket sealer on those head gaskets and you will probably have to glass those heads when your done to completely seal them. However Bars and others now have a leave in treatment for the cooling system and it works great. But that's only if you develop a small coolant leak into the cylinder after your done. I'm just mentally preparing you.

Make damn sure you have new valve seals on those heads before re-installing those are most likely all burnt to **** and will leak down into the cylinder causing misfires. (That was the problem with mine)

Also the o-rings for the crossover pipe and the front and back cam cover gaskets all need to be oem only place I could find them. aftermarkets are all wrong part or size.
But if your clever you could re-use them with some sealer.

If you need to know where I went for what parts PM me. and I'll answer you back in the thread. I'm not on every night.

OH and I don't know how much everyone has noticed but most of the engines I have seen the past two years torn down this far are 3.0's Just an observation.