John Kunkel <> writes:

While under heavy acceleration in my '87 S4, I looked in the mirror and saw "smoke" rolling out of the back, I throttled back and the "smoke" tapered off. A quick check of the gauges showed nothing amiss so I decided to try to make it home (about 7-8 miles).
Soon the temp gauge started to rise rapidly so I shut it down to investigate. After rolling to a stop steam boiled from under the car and hood and the smell of coolant was overwhelming. A quick inspection didn't reveal the leak source so I called a tow truck to haul me home.

Once home I couldn't find a leak source in the front so I removed the air cleaner to see if the heater valve had failed and, to my amazement, discovered that the elbow fitting on the rear of the right head (the one that feeds the heater water valve) had separated. The tubing nipple had separated from the machined fitting. After unclamping and removing the nipple from the hose and removing the fitting body from the head, I inserted the nipple into the fitting and found it so loose that it would wobble in the bore. I found no evidence of welding, soldering or swaging that held the nipple in the fitting. Something you might want to check the next time the air cleaner box is removed.

Rather than pay the dealer's price for a new fitting, I tapped the bore 1/2" NPT and installed an auto supply heater hose fitting. Since I don't have an
intact original, I'm still wondering how the two pieces were attached.
Anyone else suffered a failure of this part or heard of it? Any ideas on how it's attached?

Yep, had the exact same problem on my '88 the day after I brought it home from NJ just about 4 years ago. No problems since, I do not know whether the part was replaced with the newer version as that was a bit before I knew anything about cars or 928s.

Greg in Boston