Dean_Audi

It all started about a month ago with low coolant warning (A6,1999, 55K). Added coolant, started watching it daily, it was leaking, albeit very slowly. Within 2 days after the incident I started hearing a rattling sound, coming from the front of the engine. The rattle was getting louder every day.

Two mechanics did not find any visible leaks, but found pinkish residue on the bottom of the engine right below the water pump. Coupled with the rattling sound and intermittent nature of the leak the conclusion appeared to be obvious - failing water pump.

Had it replaced together with thermostat and timing belt components. Now, the rattle is completely gone, but the coolant is still slowly leaking. It is not leaking every day, it is hard to pinpoint when it happens. I drive 80 miles one day and the amount of coolant remains the same. Next day I go for a 20 miles trip and the coolant goes down a little.

Any ideas on what it can be. Does it mean that at exactly the same time when water pump started rattling, some other part of the cooling system develop a leak? If so is it a typical situation or a huge coincidence?

saabSean

Check the bottom of your radiator, there's a switch (I believe bottom right, facing the car) that can sometimes leak. It's a $30 part.

Pete RD

It is located near the turbos and can leak, but the heat "removes" any sign around the pump or "puddles". Main clue is a loss of coolant.

HTH

PaulW

However, it wasn't your water pump. A lot of mechanics jump on this when it's not the case.

The A8 has an oil cooler that leaks through plastic connection pipes to the block. Many A8 owners have had the water pump replaced when it's actually the oil cooler plastic pipes and o-rings.

You need to look for tell tale signs of coolant leaking at hose connections. You'll see pink/white residue like this:

<img src="http://www.audipages.com/Tech_Articles/enginemechanical/et1.JPG">

I'm surprised that this has not been well documented for possible leaks on the 2.7.

Remeber, if you have a low coolant alarm, it means there is a leak! It shouldn't change at all, topping it off anymore than once a year means there is a leak somewhere.

Paul

icos6

complitly

Dean_Audi

That's exactly the problem. Absolutely no signs of a leak other then the residue on the bottom of the engine directly below the water pump. The intermittent nature of the leak is also consistent with failing water pump. And so is the rattling sound in front of the engine, which is now gone.

I find it so hard to believe, that with all symptoms pointing to water pump, with water pump actually failing, it's may still be something else causing the leak.

Dean_Audi

That's scary. I presume they'd have to take everything apart again just to find out what the problem is.

PaulW

I'll bet you it's not the water pump. It's somewhere else. Take off the lower belly pan and inspect closely. If you can't find it, clean everything up then inspect again in a week.

If it's leaking enough for a low alarm once a week, it won't be that hard to find.

Do you have a bently? Look at the exploded view of coolant system and determine where all the joints are and start your inspection. It couldn't be that hard to find.

And it's not the water pump - oh, I said that before (actually it could be, but don't get hung up on it).

Dean_Audi

It's not leaking enough for a low alarm once a week, more like once a month right now, very small leak, but it is there.

Water pump and timing belt are new, they should not seize/slip and cause a major damage to the engine so I am not too worried. Will keep an eye on the situation and see whether the leak can be located or whether it will grow. It's just so frustrating to still have this problem after a major repair.

Thanks a lot.