Coolant leak

[SteelyS6]

Looks like the auxilliary radiator located inside the right front fender of my 2003 S6 is leaking again. The previous owner had this repaired twice according to the service records.

Is this a common problem?

Why does this radiator continue to fail?

Repair or replacement write up available on the forum?

Does the C5 4.2 have the same radiator or is it S6 specific?

Thanks Guys and looks like we need to find a heated garage for the weekend, -35 degrees celsius every morning here for a week and getting sick of it!

[A62TURBO]

What is the radiator for? You can't really "fix" a radiator and expect it to last a long time, sooner or later you must replace it.

[SteelyS6]

Replacement is what I meant.

Not sure what is for, looking for an answer to that question as well.

[A62TURBO]

Replacement is what I meant.

Ok, is it leaking from the core or the fitting? Is it a trans cooler?

[SteelyS6]

Crawled underneath and confirmed it's the small cooler tucked up in fender behind SAI pump. Leaking from core at bottom corner. Saw two 3/4 lines going into top, not sure where they go. Leak has slowed down now that car is warm. Will keep an eye on it. SAI is getting deletes in March when catless down pipes go in with man a flow system. If it doesn,t get worse would be fairly easy to replace I think especially with SAI removed.

Still wondering what this cooler is for? Transmission?

[A62TURBO]

It's most likely a trans cooler. Seems weird that it keeps leaking in the same spot, could be rubbing against something close by and slowly causing that leak.

[SteelyS6]

Thats what I am starting to think.

[Sparkstack]

This is the radiator you are talking about?

http://www.autopartsnetwork.com/w0133-1736324-radiator-behr/ad8fBfkT28qN2

[Audini]

Check your water pump, I had the same problem on my 4.2 and had the mechanic stumped because I would loose coolant daily. He did a pressure test a couple of times and could not find it but there would be a puddle in the morning. He finally found it after checking around with a camera. Have it pressure tested first if anything and then go from there.

[SteelyS6]

This is the radiator you are talking about?

http://www.autopartsnetwork.com/w0133-1736324-radiator-behr/ad8fBfkT28qN2

This is exactly what I'm talking about. Do the C5 4.2 sedans have this secondary radiator?

[Vinnie981]

yes

[Daily Driver]

I'm having the same problem. '03 S6 leaking engine coolant. Had the shop pressure test it - twice- they could not find anything. Have to take to stealer for the gas tank nipple recall so may have them dig around....

[Audini]

I had my pressure test done twice and nothing. My leak was coming from the water pump it was slow at first then worsen with the added pressure. It was difficult to spot at first until the mechanic used the camera and looked around the water pump and saw the drips. Cost me $1500 for the repair, I just decided to replace everything in the vicinity and won't have to worry about the timming belt, tensioners belts and gaskets hopefully for another couple of yrs.