Another coolant leak question...

[allroadinvail]

I have searched the forum and can't find anything too similar to my leak so I hope someone can help. I have an 04 Allroad 2.7t and it is leaking coolant from the drivers side. My car doesn't overheat (according to the temp gauge) and it seams to run fine. I want to say it is leaking from the overflow hose but I am not 100%. Some days its fine but others it leaks alot. The last time it happened I popped the hood and the reservoir was completely full. The next morning it was fine. I just had the timing belt and all the goodies replaced 5k ago. Could it be that the Aux water pump is not working and backing the system up? I also noticed a small puddle on the passenger side of the skid pate when I removed it. The leak doesn't always happen. I drove 3 hours with no leak but a short 20 minute trip and I had coolant all over the driveway...
Thanks in advance for any help!
Bill

[Audi_Tech]

Try pressure testing your coolant cap.

[themadscientist]

Remove the belly pan for starters. If you just had a TB/WP/Thermostat done there's a good chance that somebody didn't follow torque specs and the waterpump or thermostat housing is leaking because of that. Pressure testing the system is the best way to go.

[allroadinvail]

Try pressure testing your coolant cap.

Just replaced the coolant cap...Pulled skid plate and I have 2 spots 1 on each side of the motor. Passenger side spot is closer to the front of the car leading me to believe its the Aux water pump...I 'll try to get it pressure tested this week! Good thing I got the beater Jeep running!

[Audi_Tech]

Just replaced the coolant cap...Pulled skid plate and I have 2 spots 1 on each side of the motor. Passenger side spot is closer to the front of the car leading me to believe its the Aux water pump...I 'll try to get it pressure tested this week! Good thing I got the beater Jeep running!

You should be able to remove your upper engine covers and peer down under the manifold to see if your after run pump/hoses are leaking. From what I've seen IIRC the coolant normally runs down the back of the block when your after run pump is leaking but I could be wrong, won't be the first time! If you can't get a handle on it snap a pic and post that jank up.

[themadscientist]

Just replaced the coolant cap...Pulled skid plate and I have 2 spots 1 on each side of the motor. Passenger side spot is closer to the front of the car leading me to believe its the Aux water pump...I 'll try to get it pressure tested this week! Good thing I got the beater Jeep running!

It can be difficult to pinpoint coolant leaks without pulling the lock carrier but I've had a few customers come to me shortly after getting a full TB R&R done and they have a leak at the t-stat housing due to an amateur tech it could be the aux pump but my money is on the WP or t-stat area.

[allroadinvail]

I'll get under it tomorrow and take a look. My only question is wouldn't I see a leak immediately after the tb replacement? This service was done 2500 miles ago. I did see a leak from the passenger side 2 weeks after the tb service (aux water pump?) then nothing till recently...I have a friend that got his tb replaced by the same shop and he is losing coolant as well nor a puddle on the ground like mine. I was able to push coolant through the system by detaching the top hose that goes to the radiator to a drain bottle and plugging that hole then I blew into the overflow pushing coolant through the whole system, so nothing is stuck...HELP! Do I have a leak in the Head gasket or is it a simple fix? I know photos would help but I cant seek to pinpoint it. I am going to put it up on some ramps tomorrow and see what I can see! For what it's worth the car is only leaking after I turn it off and is parked in the driveway...

[themadscientist]

For what it's worth the car is only leaking after I turn it off and is parked in the driveway...

...which is exactly when the system pressure will be at it's highest.

I highly doubt that it's a head gasket issue.

Inferior work can take a little time to show (even 2500 miles).

I'd highly recommend removing the lock carrier when you start tracing the source of the leak.

If it's the aux pump, it won't be hard to find see. You'll have coolant residue in the block valley, running down the back of the engine.

Rent a cooling system pressure tester, but make sure it has an adapter for Audi expansion tanks.

[allroadinvail]

So I wasn't able to get a pressure tester today but I did get under it and could see much. I cleaned the underside and stuffed a piece of paper towel into the over flow hose from the reservoir to see if that is a possiblity next time it pours out. I also plugged a scanner in and watched the temp for 30 minutes and it topped out at 97 degrees celsius. Pulled code and nothing. I did notice what appears to be a vacuum leak from a hose under the y pipe
http://i879.photobucket.com/albums/ab351/xjinvail/3637F1A7-4AE9-41B9-8AB9-727F38597850-3928-0000045DD3250980.jpg
could this be related? I am gonna drive it to the office tomorrow and see what happens...Any other thoughts besides getting to the parts store before they close for a pressure tester? Also does the Aux water pump sound like a clock ticking? If so it is running after I shut the car off. If not looks like I am going to tackle that project soon!
Bill

[themadscientist]

The aux pump (after run pump) is more of a humming sound. Unless it an obnoxious ticking I would just make a mental note of it.

Considering the age of the vehicle, I would R&R all of the vac lines and check valves. Those things should be considered maintenance items but are sadly overlooked until they become a real problem. It will not be related to the coolant leak(s).

Your block 032 values in vagcom will give you an idea of the severity of the vacuum leaks.


Definitely get that pressure tester! I have an old Snap On one from the 80's that still works fantastic. It's one of my favorite tools. If you can't pinpoint it with the pressure tester, drain the coolant and re-pressurize the system with only air (it will take a while to pump it up with only air in the system) and listen for the leak. You'll hear a hissing sound.

[Ballzo]

I've got the same exact issue going on with my 03 A6. Just had TB done at 73K, I'm at about 82K now but this leaking has been going on for a while now I think. I thought it was the AC but now that I see this, I think it was coolant the whole time. I really hope its just the aux pump but I'll find out Monday. I'm taking it back to the shop to have them look at it. Its only leaking when the car is off and its just started dumping the last few days and I see that the overflow tank is empty.

[Zachariah]

Passenger side leak = A/C condensation(when used)

Driver side leak = Coolant overflow/tank/rear hose

Front of engine leak = Lower coolant hose/Thermostat housing