All,

Pretty sure that the coolant crossover pipe is the source of my '02 A4 3.0L coolant leak. Haven't had a chance to dig in yet, so I'm hoping it's just the nipple/crush washer.

Does anyone know what the part numbers are for both of those parts? Need to pick up from the dealer today and won't have a chance to pull them out until I've done that. Many thanks.

jw

 

Was the crossover pipe the source of the leak?
What was the cost of parts?
Did you happen to take any pictures while you were in there?
I may have the same leak issue...

 

They commonly leak from the nipple on the crossover pipe. Look down at the crossover pipe, more on the driver's side of the pipe there is a small hose going stright down into it. You have to remove that hose then unscrew the nipple from the pipe and replace that and the washer. If thats the source of the leak you will usually see what looks like a pink crust which is dried coolant.

 

Thanks Auditech!
What is the crossover pipe made of? Is it a hose or a metal pipe?
My leak is definitely on the driver side. I started taking parts out to get a better look. The leak only occurs when the engine is hot (I assume when the thermostat s open), if that makes any difference.
Thanks again!

 

The crossover pipe is steel, so is the nipple. Just get the crap at the back of the engine out of the way and you will see the small rubber line going into the steel pipe.

 

Oh, and its a pain in the *** to change

 

Working on it right now!

 

I haven't noticed...!

 

The hose that goes straight down (to the nipple attached to the crossover pipe) is coming from the bottom of the coolant reservoir.
I got that little sucker out (hose and clip) but not the nipple.
Do I just yank the heck out of the nipple since it will be replaced? Is does not seem to be threaded.
After looking closely at the area near the nipple I am not sure my leak came from the nipple itself unless coolant was shooting sideways toward the engine.
The leak was a big one, with hoe engine only, so I was hoping to find a cut or crack in a hose, something more visible. I guess one cannot underestimate the power of hot liquid under pressure!
I would love to finish that little project of mine and get rid of that car. Its reliability is nowhere near that of my 2000 A6 2.t with close to 100k miles, and I am still paying the lease on it.

 

LOL, thats an oxymoron, a 2.7T more reliable......
The nipple is threaded in, you need a deep socket to get it out. It has a hexagon head at the bottom of the nipple. I believe its a 13mm, but i could be wrong.
If the nipple is leaking coolant can shoot out of there with pretty good force.