Gentleman Driver

OK, did the above procedure, and let the bleed screw open with the Heater on full until only coolant came out (was very bubbly still though...). Problem is, now the water temp fluctuates greatly from above half mark when sitting yet settles back down when driving. Hot air works fine BTW.

What gives?

Thanks

PorscheG96

Not sure I understand what behavior you're seeing. You'll probably need open the bleed screw again after driving the car a bit.

FRporscheman

Try what PorscheG96 said, and if that doesn't work, try this. This is probably not what any book says, but it always works for me.

It really helps if you squeeze the upper radiator hose a few times to create some swishing and flowing (with the screw closed and the tank cap off). Then turn the car on and let it warm up until the fans come on (then you know the thermostat is open). Then open the bleeder, rev the engine manually until coolant spurts out, and once the spurting becomes a consistent stream, close the bleeder while still revving, then stop revving, and test drive.

Wash your hands thoroughly as coolant is very toxic. I mean I don't even care if I'm under the car and oil drips right into my mouth. I spit it out but w/e. But I will not let coolant anywhere near my face.

ehall

You still have air in the system. re-bleed. Also, put the nose of the car in the air. These cars need to be excessively well bled.

Gentleman Driver

OK, bled the system a number of times more, and there did not seem to be any more bubbles in the coolant that was coming out of the bleeder screw. Went for a drive and the same temperature fluctuations were happening... The car would literally get to the third hash, above half way on the water temp gauge when at rest, and then go back down to nearly cold, below the second hash when driving at highway speed... this seems extremely odd to me, especially because nothing like this ever occurred before.

I think I may have not installed the HCV correctly and the small vacuum hose is not in completely connected thus creating no suction. When I change from Hot to Cold on the HVAC, and turn the fans on and off, the Valve does not move, although I can manually push the arm on the HCV up.

Could that be the problem, simply the vacuum hose being installed improperly?

Thanks... something that seemed so simple is turning out to be difficult... but what is new?

Good news was that I did get the nerve to finally wash the car in 30 degree weather!

Thanks again everyone!

ehall

Does it get to the top line, when sitting?
As the engine revs, the coolant circulates throughout the system. I forget the exact reason, but it doesn't flow through out, when sitting. Moreover, it gets much warmer when sitting, as it should, without airflow across the radiator. Next drive, leave the heat on full, and turn on the recirc. It will blow like hell, but it should give you a better idea of what you are getting. When you get home, CAREFULLY, and with GLOVES and ARM PROTECTION, open the bleed screw a bit, until there are no bubbles, then tighten. That should finally do it. YMMV. These cars are a PITA when bleeding.

ehall

BTW coolant is MUCH more dangerous to aniamls than humans. You'll be fine if coolant gets on you. Just wash up when you're done.

SeaGull

Found this old thread while searching for heater control valve.
The links is not working in this old post.
FRporscheman, if you still are here, which valve did you use?

Damian in NJ

It says in the text it's for a 88 Audi 5000.

SeaGull

This one then?
The hose connections on this valve are not inline like the OEM valve.
Not much space. Any pics?

RajDatta

Stick with original/oem heater control vale. The original seemed to last 15+ yrs. No need to use mismatched parts.
Raj

ehall

Plus, it acts as a bit of a "safety valve", as it will blow if there is too much hot air in the system.

Jfrahm

I disagree. The OEM valve presents too much of a risk of cracking in half and soaking the RF tire with coolant. There should not be any air in the system and the safety valve is the pressure cap which should release pressure at it's set limit. I have had no problems with the metal valves in several cars, other than a ziptie or twist of wire to insure the vacuum line does not come off there were no problems or surprises installing them.

-Joel.

ehall

It's different on the 968. That isn't a problem on the 951. The valve sits at the back of the engine, so behind the wheels.

SpeedBump

Agree completely and the flow pattern is better as well.