TSHong

If you have access to an old school emissions sniffer, you can sniff the coolant expansion tank while the car is running. If you get some measurements, the leak could be so small that it would not cause bubbles, but in fact leaking. One thing is that if you had a head gasket leak, you should also see the operating temp rise as well.

parkrog2

CONFIRMED, head gasket was leaking small amount of coolant into #2 cylinder.
I brought head gasket repair product, K&W Permanent Head Gasket and Block Repair, drained cooling system, flushed it, used compressed air to blow it out, used product, idled car for an hour, drained and blew out system, let dry 24 hours. It appears to have stopped leak, no misfire in #2 cylinder
any more. Time will tell but have driven about 200 miles over 4 day period.
Still small leak at water pump, about 1/4 cup overnight. Will update as time goes on. Roger

bmwm750

Ummmmmmmmmm that kind of "repair" is for old school motors... not a modern engine like this....

aTOMic

I dunno, Jim. It's just crazy enough that it could WORK!

Seriously, it works on a concept similar to that which makes Super-Glue work (except where cyanoacrylate activates in the absence of oxygen, this stuff is activated by oxygen's presence). Might just work.
Good luck, Rog, ya crazy bastard!

TSHong

We have used this type of repair before and have had good success. Good luck.

ltooz_a6_a8_q7

My question is, why head gasket leaks? Never heard of this with all my Audis, even at 175k miles. Was the car ever overheated?

Cheers,

Louis

aTOMic

There was a TSB I saw in my Bentley manual for a recall caused by overpressure in the cooling system; fix was via installing an additional hose around the bottom of the radiator(!) but I don't have time to find it now.

JohnnyJ A6Q

Roger.
Just a thought, you might think about re-torquing the head....

Re-Torquing Head Bolts

"Re-torquing head bolts can prevent head gasket failure. Some manufacturers have issued technical service bulletins describing the procedure. (See Saab example here: http://www.saabnet.com/tsn/members/g...do=show&id=369 ) Reducing the tension on bolts one at a time (But not all the way.), then tightening in sequence is often done, particularly on engines with aluminum heads."

Once the gasket has failed re-torquing is less likely to stop the leak.

But since it seems you have stopped the leak, like I said it's just a thought.....

https://www.audiworld.com/forums/sho....php?t=2138148


http://www.saabcentral.com/forums/ar.../t-144573.html

parkrog2

UPDATE Now at 600 miles with no #2 misfire.
Car water pump still leaking about 1/4 cup of fluid overnight.
Thinking of trying Barrs stop leak to see if pump leak slows down.
Pump only has 30k on it so I suspect seal might have been damaged by back preasure. Now 90 to 100 degrees with no overheat problems. I think I can live with slow leak. Want to be sure head gasket will hold before replace anything.

MP4.2+6.0

If the pump is leaking out the front, most likely the pump seal is damaged. That leak port tells you in an easy way that is what is up. The seal of course is just in front of the bearing. While I've had Audi pumps leak there on extremely old cars (no newer than an 85), ultimately if the bearing gets contaminated or screwed up and the the pump freezes or really binds, the timing belt gives way or jumps teeth. Then your motor becomes a "coffee table" (like the guy w/ the post parting one) when the valves crash the pistons. A failing pump bearing is usually preceded by a gravelly noise, but still risky to rely on that happening before full failure. And even if that doesn't freeze up, I've had pumps progress from the small leak stuff into a full dump of the fluid over very short periods, enough to leave you stranded or if you don't get stopped quickly, motor damage--minor being more blown stuff, head gaskets, etc., and major being internal engine damage.