cnyman

All,
I now have a few major decisions to make. I just installed new upper timing chain tensioners and managed to get the right bank out of time. It bent valves and I have no compression on all three cylinders and a borescope verifies that the valves contacted the piston. (I had all the correct tools needed but obviously failed to pre tension the chain on the correct side of the tensioner). So...

I am faced with taking the head off and replacing valves. The drivers side was timed correctly but currently shows 90psi compression on all three. The engine ran fine prior to the tensioner replacement (loud ticking sound from drivers side was the symptom) After opening up the valve covers, the amount of sludge is significant. I change oil every 5k with mobil1 0w30 so this is very surprising. I have had the car since 90k and have service records of prior 10k services all the way back to 0. When I got the car at 90k, I did the carbon cleaning and there was major gunk on all the valves. So here are my questions:

With 130k on the engine, if I take the heads off and essentially do a valve job on both heads, I will likely have 90psi compression. I think that the spec is supposed to be around 125 or so. The car ran fine and got roughly 19mpg around town and 26 on the road so it wasn't a pig. It burned about two quarts of oil every 5k so that wasn't out of range. I am now at roughly 800 dollars in parts for the tensioners, gaskets and valves. Piston rings are ridiculously expensive at roughly 100.00 a set so I would be adding another 6-800 in parts if I decided to put new rings in it while I had it apart. Somehow dropping two grand in a car worth 6k on a good day doesn't make a lot of sense so I am tempted to just fix the valves, sell the car and start over.

Has anyone taken heads off with the engine still in the car? Looks doable but the bentley manual is almost worthless. I can get a used motor for 2500 but again, the numbers just don't make sense.

Any suggestions on whether to just fix the one side, do a valve job on both, or go whole hog and replace the rings and just keep the car after that? The rest of the car is pristine and as another poster put it, I would have to pry the keys from my wife's cold, dead hand at this point.

Fastbird

Some thoughts: How bad is the carbon build up? Could be potentially a cause for the low compression on the drivers side.......if you pulled the heads, had them tanked and cleaned up, reassembled with new valves where necessary, you might get compression back.

Are you still able to do a compression test currently? If so, drop a spoon of oil into each cylinder that's only seeing 90 PSI and retest. Old school trick. If compression comes up, it's piston to bore sealing. If compression doesn't come up, the problem is in the valve sealing. Just a thought that might help your decision being made.

A6 4.2 Vier

I use Mobil 1 0W40 which meets the Audi oil specs.

http://www.audiusa.com/content/dam/a...e-Bulletin.pdf

Solo786

As per the earlier suggestion . Do a wet compression test. The pressure will show more than 90psi. However bear in mind that wet tests are normally done on a warm engine. So on a could engine you most likely will not see the spec psi (125).

audifsi3.2

I don't see engine specific at list of oil. Is 10W 40 ok with any of these numbers?
Approved Engine Oils
Below are the lists of engine oils that currently meet Audi Oil Quality Standards VW 501 01, VW 502 00, VW 505 00, VW 505 01 and 504 00/507 00.

• The first four lists of products are comprised of oils that meet Audi Oil Quality Standard VW 501 01, VW 502 00, VW 505 00, VW 505 01, or VW 504 00/507 00 and are generally available in the North American market at the time of publication. The attachment lists products that meet Audi Oil Quality Standard VW 501 01, VW 502 00, VW 505 00, VW 505 01, or VW 504 00/507 00 available worldwide at the time of publication.
• Please refer to the specific Vehicle Owner’s Manual, published Technical Service Bulletins and Fluid Capacity Charts to select the appropriate oil required for each Audi vehicle.
• The lists below are also posted on www.audiusa.com and www.audic

cnyman

All,
Thanks for the replies. I mistyped the oil spec. It is mobil1 0w40. What is is interesting is that both the carbon buildup in the intake track, on the plugs, and the sludge in the heads is the worst I have ever seen on a car that has regular maintenance. I know what an engine can look like when the oil is not changed at all and this one is very close. I had to clean each allen head for the tensioners in order to get the tool to seat in the bolts. I am wondering if the PCV system is mafuctioning or something. But back to business at hand.

I did a wet compression test on the drivers side and like expected, it did come up. So is this due to "stuck" rings that are just full of carbon? One would think that at 130k, the rings wouldn't be worn out. Is there any hope in trying some sort of mystery oil or solvent to free up the rings? Again, the price of six sets of rings plus the fun and games involved in the project are really not what I have in mind. Does anyone know if the rod bolts are accessible without having to take the entire bottom of the engine apart? Shure would be nice if I could remove the pan and then push the rods and pistons out. (obviously I would need to deglaze the bores for new rings).

audifsi3.2

Hey. I think in this case so you described engine it would be better to get a new engine. Long term is better, and cheaper . Maybe the engine don't you have now at these miles only will give you problems in the future?

cnyman

All,
The head is now off, (yes, you can get it out without removing the engine...) All 6 exhaust valves are bent, 4 of the intakes. I bought 6 each so they are all being replaced. I cleaned the massive carbon out of the intake areas and lapped the valves last night. The plan is to do this one side only. I will do the normal cleaning on the other side. The only bright side to this nightmare is that the valves have hydrolic lifters for the rockers that eliminate the need for shims for valve adjustment. One small break...The cylinder walls look pristine and have some sort of ceramic coating on them. Never seen that before.

Anyway, since it is likely that the other side looks the same in terms of cylinder wear, I am going to put it all back together and hope for the best. I did the carbon cleaning 30k miles ago and the intake valves are now caked with massive amounts of buildup. I wonder what is causing this? Is the PCV system really designed to deliver that much crud to the intake? Seems like some sort of filter would be in order as this is really ridiculous if 30k miles is enough to cover each valve with a 1/4" of muck.

Some other notes: The cylinder head bolts are 8mm allen head type. They are roughly 5" down inside the head. I knew better than to use a ball type tool but the access on the two closest to the firewall do not allow a short socket type tool to fit. I couldn't find an extended reach socket version so I sacrificed one of my ball type ones and just ground the ball off to make a straight tool. This worked perfect on one but the last bolt just rounded out. How freaking perfect. So...I sacrificed a 10mm ball version, ground off the ball part and then carefully "made" a 9mm tool. Hammered it into the rounded bolt and miraculously, it came out. These are one time use bolts anyway so I have new ones but do you think an 8mm bolt head is appropriate for what must be well over 100 ft lbs when you get done turning it 180 degrees from the initial torque setting? Maybe the factory tools fit tighter than my 8mm versions but I have never had fit issues before. I will upload some pictures and create a DIY for the bent valve adventure in a few days after I get it running again.

Fastbird

Do yourself a favor and pick up a dial indicator and check your valve guides. If they're out of spec you could end up with oil consumption issues and be chasing your tail for a while. It may point to you needing a new cylinder head, but better safe than sorry.

cnyman

Fastbird,
Good call. I have one. Fortunately, the design of the head has the guides very high up in the head so the valves bent easily without damage to the guides. They are very snug with the new valves and the lapping would have shown an alignment issue if the guide was misaligned. I will check them as I have not finished installing the springs yet. Again, thanks for the heads up. You wouldn't happen to have the torque spec for the head bolts, would you? I don't have the right manual for this engine and wanted to verify if it is the same as the 2.0 motor at 60ft lbs and then 180 degrees. Thanks.