jonah290

Hi all,
I've a '98 A.8 2.8 with 274000 miles on, it's losing coolant. A pool is forming under the car. I generally need to top up by 500ml to a litre. I can't locate where it's coming from, no evidence from above or below. Though it does seem to only loose it as the car cools down after completing a journey. When the engine is hot, if I undo the cap from the expansion bottle there is a bit of a hiss but it doesn't try to shower me in scolding hot coolant. I have it in mind to change the expansion tank, as it seems very brittle now. I've not had it overheat, no gunk in the oil and no gunk in the coolant! Does the cooling system cool the ATF? Does the cooling system run through an engine oil cooler? Does any one have any suggestions please??!!

Also I'm in the UK so my steering wheel is on the "wrong" side of the car

Mark

joshe8695@yahoo.com

Possibly the plastic pipe behind the oil cooler. Mine only leaked when cold. Pain in the a$$ to get at.

silverd2

Well you've got the wrong engine, too all US D2 A8's are 4.2L V8.

If you have a belly pan under the engine, you'll need to remove it find the leak location. There has to be some evidence of where it's leaking...fluffy whitish residue from dried coolant trail.
The coolant is at it's hottest and under the highest pressure, shortly after shutting the engine off...you'll have to observe for a while right after that. Maybe slide a piece of cardboard under it to pinpoint the origin of the leak.

ATF is cooled with coils that are integral with the radiator, so ATF lines go to the radiator...no coolant lines go to the trans.

4.2L V8's use coolant to cool oil...cooler is on front left of engine (looking from front) behind the alternator.

There are also coolant pipes on the rear of the engine, under the throttle body, where heater hoses lead to the passenger compartment.

You gonna have to catch it in action or find a coolant trail.

silverd2

That's IF the 2.8 has that kind of oil cooler. My B5 with 2.8 has the cooler on the other side of the motor and is a different design, with hoses running to and from it...like on most water cooled VW's. It just a small box that the filter screws into, with 2 coolant hoses...not the block-mounted design of the 4.2.
...and YES, the 4.2 version is a pain to repair ($1000 at the dealer...I did for mine $40 and a lot of bloody knuckles). The 2.8 version (if his is the same) is easy to get to and repair.

joshe8695@yahoo.com

Sorry, didn't see the 2.8

jonah290

Thanks Joshe, Thanks Silver,
I think the 2.8 has an oil cooler such as you described, the oil filter sits on it. A bit like an oil cooler on a citroen td I had in the mid 90's. There seems to be a cooling pipe feeding into it. I've an Air/Con guy coming round later to look at my a/c compressor (that's leaking too!!) So it'll be up in the air with the pan off. The quantity of coolant lost as it cools seems to be consistant, by that I mean only loosing about 1/2 the capacity of the expansion tank.

I'll keep you posted.

Regards from the "wrong" side of the pond

Mark

silverd2

If it has the type cooler that bolts to the block, it likely has a short hidden coolant pipe (plastic, unfortunately)between the cooler and the block, that always goes bad eventually...the plastic turns to brown sugar and leaks increasingly bad.
It also has a metal pipe on the outside that you can probably see...I think this is what you described.
These coolers work very well, but Audi should be shot for using a plastic pipe in direct contact with a hot engine block...inexcusable. There's a member on Quattroworld forums that makes an aluminum replacement for this pipe, as Audi engineers should have in the first place.

melmaddock

I had the same problem amout a month after purchasing my 98 A8. It was the plastic connector that connected the transmission cooler to the block. Amout 1" in length and was broke in half. The trick was to connect the other lines with the new O rings but once I figured that out - never had any coolant leak afterwards.

Good lick

Have you checked out audipages.com - great info.

silverd2

That's the engine oil cooler, not the transmission cooler.
The trans cooler is built into the radiator and is cooled by air, not coolant.

jonah290

Thanks for all the response guys,

Mel, I think you may be talking about the V8 block, I have the V6. As Silver pointed out earlier, you chaps in the States only had the V8's. Thanks for the comments. As far as i can tell the V6 oil cooler is what the oil filter screws into. Looks like a raised platform about 20mm deep that is sandwiched between oil filter and block. I have looked at audipages.com quite a bit, it is really informative but again it all leans towards the V8.

Silver, The guy that does my repaires thinks it may be the waterpump (but he only had a quick look), I'm going to take it back in to him next week. The waterpump is only about £40($30), it is due a cam belt kit and the A/C compressor needs replacing, so it could all be done at the same time. There have been some funny noises, grinding/squealing type noises when I've 1st started up over the last couple of days. A water pump giving notice perhaps??

All the best
Mark