Hi Fellow A6 Avant Owners

I have a 2001 A6 Avant, and I noticed one morning that there is a small puddle of coolant underneath my Audi. The coolant reservoir has NOT been drained, and there are no signs of leak from it. And the weird part is, the leak is on the opposite side on where the coolant reservoir is located.

Normally, i see the leak when the car is parked overnight. But if the engine is running, even if the car is just parked, there is no leak. The leak is like droplets from a moist water bottle. And it is dripping from the edge of the Oil pan. and beyond the oil pan is i think where the Alternator is located and thats how far I can see.

I tried checking underneath one morning, to see if the hoses there is leaking, but they are all clean. no signs of leak, im just not sure if there are other hoses other than those visible from underneath. The coolant that is leaking has no signs of engine oil, so im assuming that my engine gaskets is still intact.

Any ideas on what I am dealing with? Thanks

 

Assuming you have the 2.8 engine and that the leak is from the front of the engine, best guess would be t-stat housing or water pump. But, why guess when you can take it to a mechanic and have it put on a hoist and investigated properly.

 

I guess this is going to be a guessing game..

I have a couple of mechanics check trace the leaking coolant, and NONE can pinpoint the exact location. They did some high pressure test and found nothing.

It seems all of my hoses are ok, and no leaks. RIght now, I am entertaining the idea of my water pump failing. My coolant gauge went 2 lines from the usual middle. I noticed this after re-starting my engine, coming from a 30mile drive. But it gradually dropped down to the middle. Altough, my timing belt with the water pump was change at 120,000 ++ miles, im now 135,000 miles.

Have any of you guys experienced this? Any more thoughts?

 

You can not be serious, guessing at a coolant leak!

Do not even tell me your so called mechanics verified a coolant leak and couldn't find it. How could that be possible???

Let's start at the top then.

I can not imagine having a coolant leak on an engine and not being able to find. It could be a pita but come on...

Is it coolant for sure or just water. Have you touched it and smelled it?
if it's water it could be from A/C or some other non important place.
With my cars I notice it is wet just before the passenger pan on the ground all the time. Put a white pan under the leak to catch the fluid.

Is your level in your coolant reservoir going down?
If it is. and your leaking. remove the belly pan run it and park it then get under there and look for drips. Determine whether it's coming from the front or rear of the engine. Get a telescopic little mirror and a good flash light.

If it's the front look at your hoses and pump it will have white crusted crap around the leak. Don't second guess a pump replace it. If the seal is going the bearing is next and that could lead to bent valves.

When they did the pump and belt did they do the thermostat and hoses???
Use an Audi pump or something real good. It should be no surprise that a china pump or seal fails, They can't even produce milk over there.
and you should have replaced every hose on that engine by now so if they are originals that could be a problem.

If it's leaking from the rear it could be the cross over pipe and there was a couple of small cooling hoses under the intake manifold on my 3.0 so I would imaging a 2.8 has some too.

Get me some intel here.

what color is the fluid?
is it leaking from the front or back of the engine?

 

A good mechanic should be able to add ultra-violet dye to the coolant and then you can find the leak using a black light in the dark. If it's in the front, you are probably looking at the water pump or the water pump gasket. Since the wp is relatively new, unless you had an unusual early failure I would suspect gasket. Or as posted, it could be a leaky hose since you have high mileage. (I'm about to bring my A6 in for it's second timing belt at 184k, and will probably replace all coolant hoses just to be safe.)

 

There's no coolant line/hose on the opposite side of the collant reservoir.Obviously if you're not mechanically inclined, take your car to an Audi/VW dealership since your private so-called "mechanics" told you they can't find anything and is a "guessing" game.
If you have a 2.8 engine, then look for the following:
1. The radiator draining "plug" - is just a stupid plastic part. Aging causes it to let coolant leak around the threads. It drops on the belly pan and can pool up near the rear edge of it, passenger side.
2. If it is dripping FROM THE EDGE of the OIL PAN, as you said, then it means something is leaking up and trickles down onto the engine.
Places to look for: - as Bob said it, T-stat or water pump housings, both front and rear (under the intake manifold). I would personally suspect the O-rings in the back of those two housings (the coolant pools in the valley pan), but since we're talking about an Audi... anything is possible. As someone put it: this car brand is a leaking sieve.

 

Thank you guys for all your inputs.

I am using an orange/pinkish coolant color, and i was able to get about a tablespoon full of coolant overnight. This is just the amount of leak i get everyday. I pulled up the service records from the previous owner, and all the hoses and thermostat was replaced during the timing belt change. It is leaking on the back of the engine.

Hope the pictures helps. Thanks again for all the info. This would help alot once I find a mechanic and I'll know if he know what he's talking about.

 

take it to any rad shop with your pics .. they should be able to pressure test and find the leak very quickly .. cases like this you need a system specialist , not a car specialist .. this is not an Audi problem as much as it is a coolant system problem ..take it to the cooling system specialists ..

 

-> Re-opening thread <-

I was advised to replace the lower radiotor hose and the hose from the aux water pump to the thermostat. So I did, all hoses are installed properly, no signs of leaks on the hoses. I also bled the coolant, by running the engine with the coolant reservoir open and running the heater on for a few minutes.

After I few days though, I noticed that there is a coolant leak on the same spot as before. Surprisingly, If i open the coolant tank (once the engine cools off) there is a small amount of air that comes out, and I started noticing if I do this (
open the coolant reservoir to let the air out), i dont get the leak the following day. I did it a couple of times, and I dont get the leak the following day unlike the days that I dont let the air out.

Any idea on what my problem is?

 

I have the same problem with my 2002 2.7T, tablespoon or two of coolant leak dripping off the right side of the oil pan. The car needs to cool for about 8-10 hours after driving to cool. I have had it pressure tested too (before it cooled those hours) and it was fine. Today I added a dye to the coolant and have been checking for the leak, but as you pointed out, opening up the coolant reservoir prevented a leak the next morning, so I might not have any luck tonight as I opened it after parking. I'm of the mind that two metal pieces when cooling contract and allow a bad gasket to leak enough to let off some pressure, so it would need to be higher up on the engine where after a small amount of fluid comes out, air can leak.