bradwilcox

I see a lot of references to the C3 and C4 20v and V6 and it has not helped me with my 10v 1990 200tq issue.

I flushed the coolant, refilled it and am unable to find an air bleed valve anywhere, even under the plenum cover. Failing finding it, I have loosened hoses throughout the total path of the coolant and verified that the coolant is traveling from the expansion tank through the block up to behind the dash and back to the expansion tank.

The 200 is not happy, though. I get the warning light almost immediately after ignition that the coolant is either too low or too hot.

The heater blows hot.

The radiator fan does not turn on after a while. Caveat: it may be going to turn on but I am afraid of overheating the engine so I don't run the car very long. The block gets warm but I don't push it without the fan.

I drove leisurely around the neighborhood just now and the warning light stayed on. Heater blowing warm. No fan. Parked and turned off engine. No fan. Sound of mild boiling from in the block area. Carefully opened expansion tank. A bit of a hiss but no geyser.

Everything worked fine until I did the coolant swap. Thermostat was working fine. Wondering if now thermostat is not opening. Don't know why it wouldn't. Don't know if it's a thermostat issue or an air bubble issue or what.

Yes, I am a rank amateur. Will appreciate any advice.

yodasfro

When refilling the with coolant you want to fill the block first via coolant neck on the cyl. head. Then top off the reservoir. You are correct there are no bleeder valves, you can run the car up to temperature with the coolant reservoir cap off but closely monitor the coolant level to avoid any spillage when it burps. Set the CC heat to high on the econ mode so the rad. fan doesn't turn on thus making it take longer to get up to temp. Two things can trigger the warning lamp either low coolant level in the reservoir or overheat signal from the MFTS big coolant temp sensor on the bottom of the coolant neck.

bradwilcox

Yodasfro, thanks.

I assume you mean the coolant neck on the cylinder head basically at the MFTS, just above the MFTS?

I just went out and loosened that hose with cold engine just to see what would happen. Nothing came out even with hose removed. No pressure needed to be relieved.

Car is seemingly full with new coolant. At least I had added the right amount.

I reseated the hose and warmed the engine up next with econ heat running. I got hot air pretty quickly. I loosened the hose carefully. Tiny bit of air and tiny bit of coolant came out. Took hose off entirely. Engine running and barely any coolant coming out. Like maybe a tablespoon every 2 seconds? I looked in the expansion tank and it was going down, but very slowly at the same 2 tablespoon rate. At this point it had been about 5 minutes. Finally the coolant warning light came on. No radiator fan came on. I was nervous to overheat the block, so I shut down. No after-run fan. With engine now off nothing really came out from the block. Put hose back on.

Again, assuming MFTS and wiring is good, shouldn't I be getting radiator fan and much more travel in the coolant?

It seems to me that there is small portion of the total volume of coolant trapped in the block. The block thus is getting hot while the radiator is still cold. Thus no radiator fan? But then again if the block was quarantined behind a closed thermostat, the expansion tank would not have gone down when I had the hose on the block off.

The thermostat was fine before I flushed the coolant.

twentysevenlitres

Does the 5cyl have an engine driven fan (I assume it does as Audi only started trusting thermofan only installations in their longitudinal cars around 2008!)?
Or does it have one of those offset radiators?
If it has an engine fan, the electric fan will be auxiliary only - coming on for aircon boost and very hot radiator only.

Is the radiator getting hot?
Is the top hose hot?
what's the temp gauge reading?

With heat through the heater core, the system should be well bled (as usually the highest part in the system, any air locks will usually prevent the heater from working).
I'd be looking to the thermostat or radiator fan switch if it is actually running hot.
If it's imaginary, I'd look at the coolant temp switch.

bradwilcox

New tidbit: with heater on econ mode the radiator fan does not come on, at least not by the time I get nervous about the block overheating and shut down.

If I turn the heater on "auto", the fan comes on.

I think that is working as intended.

But either way, I'm still getting coolant alarm and very weak flow of coolant coming out of the block back toward radiator.

audidream2

The cooling fan switch is located on the lower part of the radiator. If you do not have coolant flow to the radiator if cannot sense coolant temperature to control the fan. I would remove the thermostat for testing purposes and start the engine and confirm coolant flow. I do not know what ambient temps are at your location but it should need to run at least 10 minutes before needing a cooling fan. What is the temp gauge on the dash reading? I have never had a problem with bleeding the cooling system. If you leave the coolant cap off until the thermostat opens it will self bleed as stated in an earlier post. Let me know how that goes and I can give you further instructions.

audidream2

A little more info. The type 44 Audi 5000/100/200 10V does not have a mechanically driven fan. It has a 3 speed cooling fan. When you turn the climate control to Auto or Def the fan turns on stage one to cool the A/C condenser. If the climate control are Off or on Economy the fan will not come on until the cooling fan switch tells it to therefore stage two. There are different temp fan switches so I can tell you what temp that would be but you should not be getting an overheat light. The third fan speed is very hard on the electrical system and will only activate for brief periods and then it will step back down to step two.

x19

But either way, I'm still getting coolant alarm and very weak flow of coolant coming out of the block back toward radiator.[/QUOTE]

When it's over heat or not warm up to normal temperature etc.
There are no coolant leaking and(or) cooling system pressure leaking etc. then you can move next. Cap sometime wouldn't hold pressure.

Coolant level sensor is defect or loosen electric wiring at the connecter may be.

I will use the old radiator hose If size is OK and connect to mouth of coolant tank which makes highest point (air out) when pour coolant regardless of engine running or not. (I'm in LA,CA)

BTW, do you have a Infrared thermometor gun?
Good luck. x19