After I drive my 2001 a6 and let it sit over night I typically have a puddle of antifreeze under the car. It happens most nights after letting it sit and I know it is antifreeze by its color and have been monitoring the coolant level in the expansion tank. Just as a reassurance as well, the low coolant light came on once too.

I also have pressure in the coolant system as when I loosen the cap to the expansion tank pressure is released.

I jacked the car up and pulled off the bottom cover but all of the hoses seem to be dry, there is just a large amount of antifreeze dried on the bottom of the oil pan. It also appears to only be leaking from the right side (if you are sitting in the car).

All is dry underneath the coolant expansion tank as well and I cannot see any visible leaks. There are only 38,000 miles on the car so I don't suspect its the water pump. Also, the water pump is in the front of the engine and I am not seeing any coolant residue there.

Lastly, I never over heat while driving, the temperature gauge always remains in the middle when it reaches normal speeds.

Has anyone else experienced this and found a root cause?

Thank you in advance for your responses,

Matt

 

Pressure in the coolant system is normal. As for the leak, it can be any of the hose connections. There is a coolant cross over pipe at the rear of the motor which can be the cause. Or the hoses from the throttle body to the heater core could be it too. There is no other way to find it other than just looking and tracing the leak.

 

Most likely the water pump but could be a connection on the lower crossover pipe.

 

You did not tell us what engine. The 2.7T has a secondary coolant pump on the rear of the engine that often fails slowly, and leaks. Mine tended to dribble down the back of the engine and over the front of the tranny, where it often evaporated due to heat. Not sure it would land on the plastic belly pan as you say yours is.

 

My 2.8 suffered a leak from the main hose to the heater core around 180k.


-RZ

 

Thank you for the responses thus far. PPGoal it is a 2.7T engine in the Audi, I wonder if it has to do with this secondary coolant pump that you speak of.

I have not heard of a secondary coolant pump and I also have the Robert Bentley repair manual if you would be able to provide a page number to describe more about this.

Thanks in advance

 

Start by removing the undertray. Leave it off. Put a clean sheet of cardboard under where you park and park over it. Mark the cardboard where the tires meet it to get a reference point. Let it leak out onto the carboard. Now you will be able to determine where to start looking. Get under the car with a bright flashlight. You can shine the flashlight around the engine and look for the shiny spot which will be the coolant trail. It will be HARD to spot. You must have a good flashlight. Use the location derived from the cardboard experiment to narrow your search area. Look for a wet streak or a small drop of coolant which will form at the low point of the drip trail. Follow the drip trail up. If you still can't find it, get a can of spray foot powder. SPray the engine where you think the drip might be. Run the engine. The drip path will stand out like a sore thumb. Keepi going up until you find the source of the leak.

Good luck,

Bob

 

Thank you for all that responded. I pulled the slash guard off again and studied the stain pattern of the coolant leak for quite some time. After examining the stain and referencing my Robert Bentley manual it looks like the leak is coming from the Auxiliary Coolant Pump.

When I look under the vehicle a majority of the coolant is leaking under this pump. Also, I have done some searching at this forum and throughout the internet and have discovered that this has been known to leak. While I am 90% this is where the issue resides, I will not be certain until I remove the intake manifold to examine it further. However, even if it is not this pump, with the engine dissected I am confident that I will be able to determine its root cause and repair the issue.

At this time I also intend to replace the spark plugs, anything else anyone would recommend checking or replacing while I have the engine apart?

I do have a 2.7T engine
38,000 miles on the 2001 A6

Thanks again

 

I'm having a similar problem - coolant leaking on right side of engine. I can see drops of coolant on the side (closest to the block) of the alternator. Since I have not taken off the intake manifold, I can't see whether the leak is under the aux water pump. How did you manage to see it? Others with aux pump problem have reported the leakage in the back of the engine, over the tranny.

I would appreciate knowing your progress in solving this problem.