MY 2006 A8 IS LEAKING COOLANT SOMETIMES BUT NOT ALWAYS. FINALLY TOOK OFF ALL LOWER ENGINE COVERS AND FOUND DRIPPING FRONT LEFT BELOW WATER PUMP. CAR
ONLY WILL LEAK OVER NIGHT SOMETIMES BUT NOT DRIVING OR PARKING AT WORK.
COOLANT RESERVOIR WAS REPLACED BY DEALER 1 YEAR AGO. SYSTEM ALWAYS HAS PRESSURE WHEN YOU REMOVE CAP, EVEN AFTER SITTING ALL NIGHT. I THINK MY CAP MAY BE DEFECTIVE SO OVER NIGHT COOLANT SEEPS OUT OF PUMP! ANYONE HAVE SIMILAR ISSUE???

 

<a href="http://www.dognmonkey.com/audi/2000-a8-40v-oil-cooler-plastic-pipe-replacement.html"> Oil Cooler Plastic Pipe</a> Do they still use the same one on D3 40V? If it is, lots of work.

Cheers,

Louis

 

If it is literally leaking at lower area of the pump itself, it has a pump issue. Two possibles: less likely is the gasket where it bolts up to the block. More likely: the seal is shot. When a seal starts to fail, it typically will leak coolant out just below the center shaft area where the pulley bolts up. Typical modern water pump design is to drill/cast a little port in there so that if the seal fails it will pee out some coolant and help signal there is an issue.

If it's that seal area drain hole, only fix is a new water pump, which then invites the timing belt job question. And similarly, if the seal, you neither want to run the risk of running motor w/out coolant nor that the seal leak issue getting into the pump bearing and eventually freezing up. That is more a very extended neglect scenario and usually accompanied by squeals or gravelly bearing failure kinds of noises, but it makes sense to resolve pronto anyway.

BTW, on the cap it shouldn't ever release pressure under normal operating scenarios, so a cap malfunction here wouldn't be the cause. Instead, per the normal operation, the system stays under pressure for some hours as the motor cools down. Unless the car overheats and the cap then dumps the coolant to the ground under a lot of pressure, if anything the cap functions more in the other direction. Thus, if the car is low on coolant and has more resulting air volume in the cooling system, when a vacuum condition develops (like the system cooling down), the cap can let air back in to the reservoir area so the hoses don't start collapsing.

 

I was actually going to post something on this topic a day or two ago. I've noticed a coolant smell from the front driver's side of my 07 D3. I've gotten a couple of low coolant warnings, after which, I added a minor amount of coolant back to the reservoir to restore it to the proper level. I've also noticed on more than one occasion (but not continuously) a deposit or leak of coolant near the inside of the front driver's wheel. Whatever the leak is, it appears to be extremely slow and intermittent. Was going to ask if others had experienced similar problems...

Thanks!

 

WATER PUMP AND TIMING BELT DONE 30K AGO BY DEALER.
I AM GOING TO RELEASE SYSTEM PRESSURE TONIGHT AND SEE IF LEAKS OVERNIGHT.

 

System operation is under pressure while it cools down for hours. If you are loosening the cap, that isn't normal operation. And again, cap should NEVER release pressure anyway in normal operation. Instead you should focus on simple fact it's leaking, not the pressure element that is normal cool down.

That belt and pump done 30K ago is interesting but again not determinative. Failure rate is > 0 regardless of miles; it just goes up more later. Net, if you have timing belt and engine covers off, you want to get to exactly where the leak/drips come from, like literally within a few millimeters. Without that, you are on a wild goose chase and then we're all just guessing.

 

I found something like this recently. Overflow coolant hose on W12 involves a bunch of hard plastic molded pieces that route to rear of engine and also up toward radiator. One of them cracked and allowed a bit of leakage.

4.2 set up will be different on specifics, but in general I would trace your overflow line back looking for leaks. If you find a very faint pink crusty sort of deposit on or near any line, clamp or hose, that's where a leak resides. That pinkish stuff is the coolant residual as it burns off; helpful for finding leak sources actually.

 

I replaced my water pump on my D2 (no experience then) when I saw the coolant leak under the car, the leaks were still there - then opened it up again - it's the coolant pipe.

OK - The symptom of the coolant pipe is this - over 120k miles both of my D2 32V and 40V.

The leak is on the passenger side - by the starter -
Only leaks when the pressure of the system is high = Hot and engine OFF, will not leak when engine is running.
Leaks a little - then a lot after a few weeks.

Cheers,

Louis

 

I have to ask; did the dealer use genuine parts or was it a Blauparts kit? If so, check the CONdition of your serpentine belt right away. Of course the main reason I ask is because my Blau water pump started to leak with only 72,000 miles on the pump. Way less miles than the OEM pump.

 

That was my question. I have that kit sitting in my garage.