Stop me if you've heard this one before....... My 99 A6 2.8Q's coolant reservoir is cracked (2nd one in 103K miles). Does anyone have a good tutorial or general advice on how to replace it? I'm somewhere between clueless and mechanically inclined in terms of technical skill, but my mechanic said it the job is pretty simple.

 

Considering its cracked twice so quickly i would also inclued a new cap in the mix. Sounds like a cooling system overpressure issue. As for the replacements it is easy. Pop the hood and its on the drivers side right in front of the cowl. Youll need a phillips screwdrivers and some hoseclamp pliers. A small screwdriver or pick and some silicone spray will also come in handy as the hoses can sometimes be stuck in place. Thatll be your biggest chanllenge. Other than that its a piece of cake.

 

Thanks for the advice. I have heard that these reservoirs fail quite frequently. There is a pin sized hole that leaks only when the car has been driven quite a bit, so I want to replace it before time and pressure take their toll on it even more.

 

I've had 2 fail in the last 2 months... just like you described. When the engine is shut off, it heat soaks, builds pressure, and voila, the coolant starts streaming out of one or more pinholes.

I'm surprised I haven't heard of more failures from other hot climate Audi owners.

I live in Texas, and we've had over 30 days of +100 degree weather, ugh.

I've tried "melting" the cracks shut with a soldering iron. My next solution is to use a polyethylene glue, and if that doesn't work, I'm building an aluminum tank.

 

The cooling system pressure should only raise to about 14psi no matter the condition, car off or on. Any more than that indicates a failed cap which can cause repeated failures.

 

Resolution...

After having two coolant tanks fail (aftermarket, Meyle brand), I went to the VW dealer and picked one up. The tank is definitely "molded" a little differently... its much more "clear" and has a much smoother surface finish. The mfr. markings are VW/Audi.

My initial thought is the aftermarket tanks sold by various parts houses (I bought mine from Arizona Autohaus) are inferior to the "real" thing.

I'll post my results after another week of Texas "heat-wave" weather.

 

I replaced the tank last night. Dankhound, you were right, it was a snap. The hardest part was emptying the coolant from the old tank. I didn't get a new cap but I think I will order one as it cannot hurt. Although I live in New Hampshire and can't speak to consecutive 100 degree days, the leaking of the tank did appear most significant on what we consider hot days (high 80s)