Help with a mysterious small coolant leak, here's the deal, details inside
Thread Starter
AudiWorld Member
Joined: Jan 2007
Posts: 241
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Help with a mysterious small coolant leak, here's the deal, details inside
I had a leaky water pump and failed t-stat, so 3 weeks ago I had those two items and labor covered under my extended warranty, and while the mechanic was at it I paid out of pocket for new pulleys, tensioner, t-belt and serp. belt. Major service out of the way, nice. The day after the repairs I notice a very small coolant leak on the garage floor. I figured maybe the mechanic overfilled the resi tank. The days went on and so did the leak, so a week later the mechanic checked under the car while up on the lift and neither he or I could see any obvious signs of a leak. He said I would have to wait until it became obvious so we could then fix it.
Here are the symptoms: it only leaks a tiny bit over night. It does not leak during the day driving around, while at work as I can tell. It seems that when the entire engine fully cools down that the leak finally hits the belly pan and then the floor.
I STFA and from what I can find it may be the oil cooler.
ANY ideas will help. My warranty ends in 300 miles and I would like to fix it by then.
thank you all
Here are the symptoms: it only leaks a tiny bit over night. It does not leak during the day driving around, while at work as I can tell. It seems that when the entire engine fully cools down that the leak finally hits the belly pan and then the floor.
I STFA and from what I can find it may be the oil cooler.
ANY ideas will help. My warranty ends in 300 miles and I would like to fix it by then.
thank you all
Tech Guru
Joined: Oct 2002
Posts: 8,009
Likes: 191
From: Olney, MD
Get some fluorescent dye and put it in the reservoir. Run the car
for 10-20 miles and put it in the garage and search for the leak with a UV light. You'll have to take off the belly pan before you do this and either clean the belly pan thoroughly to get the existing coolant off it or leave it off while you're searching for the leak.
The moron service facility should have used a dye tracer first thing.
Prime sources of leaks are the coolant reservoir itself...it often cracks on the bottom.
There is also a plastic coolant line (at least on my 2K 4.2) that hardens over time. Also multiple spring clamps that leak (and should be replaced with screw-type clamps).
Good luck.
The moron service facility should have used a dye tracer first thing.
Prime sources of leaks are the coolant reservoir itself...it often cracks on the bottom.
There is also a plastic coolant line (at least on my 2K 4.2) that hardens over time. Also multiple spring clamps that leak (and should be replaced with screw-type clamps).
Good luck.
Thread Starter
AudiWorld Member
Joined: Jan 2007
Posts: 241
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Yes you are correct about the mechanic, very good Audi man of about
25 years, very fair pricing, but can be either too busy or lazy when the problem is not blatantly apparent. I have been going there for 15 years now and 4 different Audis because there is no one better for the $ in my town. They always diagnose for free, and they have given me a few small fixes over the years for no cost. In the case of the leak check he was busy that day as I just dropped in for the quick check under the car. Where do I get the correct dye? Any auto parts store? Or do Audis need something specific?
thanks
thanks
Audiworld Junior Member
Joined: Aug 2003
Posts: 79
Likes: 0
From: St. Louis
Re: Any auto store should have the dye or get it online.
I had a similar problem and it ended up being a small hose that runs to the oil cooler. My best guess was that the cooler was twisted during a repair and the hose got pinched between the cooler and the engine where it promptly rubbed a hole in the hose. It was a pain in the *** to repair. Good luck with the dye.
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