nyrobbie77

My 97 Audi A8 has developed quite a large coolant leak. It was fairly small, only needing topped off every 6 months. About a month ago I started noticing a sizeable puddle on the ground, right front engine area. Some nights there would be nothing, other nights a puddle 2 ft in diameter. Now I'm adding about half to 3/4 gallon once a week. I've been traveling for work (not using the car) so I haven't been able to determine the source of the leak. I've been under the car but nothing is obvious - hoses are dry, radiator is dry. Its definitely an external leak as I see it on the ground - oil is clean, reservoir other than empty is clean (no oil in coolant).

I'm suspecting that the oil cooler pipe has broken. I have the replacement (aluminum) pipe and gaskets and plan on tackling this repair via the audipages instructions this weekend.

My question is, can the oil cooler pipe leak this severely? Due to an oil leak from the timing area (guessing front cam seals), its difficult to find just the coolant leak as its wet from the oil and our rainy/snowy weather.

I was hoping to do the timing belt/water pump at the same time, but my local audi guy is waiting for the tools he ordered. So I may have to do the oil cooler then TB/WP another time. I'm planning on removing the front end to give a little better access to the oil cooler.

Any insight as to whether I'm on the right path or not is much appreciated. Any tips other than whats on audipages for the OC repair is also welcome.

Thanks in advance.

silverd2

Yes the oil cooler pipe can leak severely and change back to intermittent.
Get under the car after it's cooled down and look (with flashlight) up behind the alternator ... you should see some dry chalky residue from the leak.
If the pipe has never been changed and you have 100K miles plus, it's bad .. they all go bad ... likely in pieces already. Shifting/expanding-contracting pieces and parts (block & oil cooler housing) can cause the leak to come and go at will.

I didn't find the front end removal necessary (maybe a better line of sight) to get to any bolt ... I removed the airbox and fender liner entirely to do the job. You may need to "invent" the right length tools to get to each mounting bolt ... have extra allen wrenches of all lengths ... I had to custom cut one for the upper left bolt, but things are slightly different on 32V compared to a 40V cooler.

Do whatever it takes NOT to strip an allen head...do what it takes to have each firmly seated before turning!!!

nyrobbie77

Thanks for the great reply. I have 195K on the odo now, no idea if anyone has changed it before. I'm going with the aluminum nipple and hopefully won't have to ever deal with it again.

I'll update with some pics and my findings once I tear into it this weekend.

Thanks again and Merry Xmas.

nyrobbie77

well I tore into the oil cooler repair this weekend. I used a mix of tips from audipages as well as silverD2's. I didn't put the front end into the service position, but I did remove the front bumper. This gave me a little more room to get at the alternator bolts with out scraping my hands on the bottom edge of the bumper cover. I also removed the right front headlight which gave me a little more space.

I could not figure out how to jack up the engine as instructed on audipages. I removed the two rear engine mounts, placed the pipe and jack where specified and it would only lift the entire car. I'm thinking in order to do this I would have had to remove the 3 bolts on the torque arm where the jack was placed to lift the engine the required 3 inches. this step isn't mentioned in the audipages instructions.

One of the notes on audipages suggests removing the inner fender liner. After spending an hour trying to get to bolt #1 on the oil cooler and trying to lift the engine without success, I decided to try this route. after getting the liner out I was able to see the #1 bolt, well where it was supposed to be anyway. Apparently who ever did this job last did not like the #1 bolt and decided not to put it back in (see pic below). the rest of the bolts were easy to get to at this point. #2 I just used a standard 8mm allen head socket, 3" extension, swivel and 6" extension. I made sure to tap the allen socket into each bolt before breaking it loose.

As you can see in the pictures below, the nipple was definitely cracked inside the block. I still need to fish out the remaining piece, clean everything up and re-install. I ran out of brake clean and kerosene for my heater. You can see the oil leak trail which appears to go all the way up to the cam shaft seal area. It puddles around the head gasket area, but I can see oil above it. I hope to change these out this coming weekend.

Thanks to everyone's hints and tips. enjoy the pics.

QUA8RO

I'm in the same boat myself. I wonder how many hundreds of us have tackled this job ourselves? Somewhere in Ingolstadt there's an engineer named Klaus who's responsible and unaware. Or very embarrassed.

My oil cooler has the smudge in all the same spots as yours. Hope this fixes it.

Question (I've posted it elsewhere, but why not in this thread as well):
The o-rings should go on the water pipe as shown in your picture of the aluminum pipe, right? I have the same replacement pipe but am wondering if additional o-rings should have gone at the *end* of the water pipe as opposed to around them?

Same question applies to the metal pipe attached to the engine block at the back of the oil cooler. o-ring around it, not at the end?

For my tear down, I put the car on jack stands, removed front fender, removed the whole radiator/lighting assembly, removed alternator, and jacked up the engine to get the oil cooler out. I'll jack it up again to get the oil cooler back in.