Alright well I've researched this quite a bit and it seems that no one has really found any resolution for some strange coolant issues. First of all the car is a 1996 A6Q with an automatic transmission. The problems first began last week when the car began to throw the low coolant light at me as I was parking the car so I didn't really give it another thought until the next morning when I checked it and it was low. So I checked the hoses and tightened the clamps on the tank and refilled it. A couple days later I ran to the gas station to fill up and as I was parking again the low coolant light came back on and the A/C seemed to stop and start pumping in only mildly cool air with a lot of humidity. So I pop the hood to find that the reservoir cap is steaming along with all of the hoses and a bit of an overflow as well. So I let the car cool down before I got close again and started inspecting. My fans are always on, no matter what temperature or if the A/C is on. It was fifty degrees F the other day and the car was cool from the night before. As soon as I start it the fans come on with no heat or air on. Sorry for the wandering, back to the inspection. So on the driver side of my radiator the hoses and the radiator are still hot and the on the passenger side the hoses and radiator feel stone cold. Here are the things I've done so far to try diagnosing/fixing the problem.

1. I ran the till it warmed up with the heater on and checked the radiator, it seems as though the coolant is never even getting through the radiator. So while flusing and pumping gallons and gallons of water through it all I see is old coolant and water, no dirt or mess at all. Well I put everything back together and still no dice, over heats and blows the lid.

2. The next day I bleed the system for air using the purge valve up by the windsheild. The car begins to cool normal with the heat on with the ac on as well. Both sides of the radiator heat up as normal and there is no bowling or explosion from the reservoir. I think success and take it for a quick test drive and play with the climate control. Twenty minutes down the road I start to fiddle with the A/C by turning down the temperature on the unit and just pump out cold air. As I do this I switch it back to heat and wait a few minutes but the heat never resumes. It stay ice cold even with the A/C off and the temperature all the way up. I lug home defeated.

I really need to get this car up and running again since my brother is getting tired of lending me his car to get to work everyday. Any suggestions toward why this would occur and perhaps giving me a few options toward what my next move should be. I've considered pulling the radiator and taking it to a shop to get really flushed. Which brings up another question. Is there a trick to getting it out of there, is it normal to remove the entire front end (bumper, lights, and top radiator mount?) Well sorry about the length, but thanks to anyone taking the time to get here. TIA.

 

The thermostat can be changed without disturbing the timing belt, despite what Bentley says.

I'm not exactly sure how I'd check the water pump other than pull a hose and see if coolant pumps out.

Are you leaking coolant before it blows out the reservoir cap? (any puddles on the ground?)

Check the heater control valve, bleeder valve, and hoses under the plenum cover between the firewall and windshield for leaks.

 

1) You have a coolant leak that needs to be located.....hence the low coolant warning light. The water pumps like to leak as they get old. The coolant tank break in several places and then may only leak under pressure when the coolant heats up.

2) You have fans that run all the time from either a failed radiator fan switch or someone has jumped the wiring somewhere...like at the switch. This is called "Masking a problem by creating a new problem." You need to find out why the fans run all the time and you can start by looking at the fan switch on the radiator and testing it (no continuity through the switch when the coolant is below about 95*Celcius/195*Fahrenheit using an ohm meter

3) You have coolant that's not properly circulating, and this could be due to blockage in the radiator, blockage in a hose, air in the system, or air in the system from a blown headgasket.

If it were mine, I'd take the plastic engine covers off and replace the thermostat and check to see if the water pump is leaking. While the thermostat is out, I'd disco any hose I could get to and then start back flushing everything seperately with a garden hose and one of those pistol grip spray nozzles. Only when I had good flow and clean water coming out all "zones" would I start putting things back together.

With a thermostat (and possibly water pump) installed, I'd put it all back together and fill with 50/50mix of phosphate free coolant. Perform the bleed method that I talk about in BMThorn's thread from a couple days ago. I'd make sure I had heat, and that the radiator fans were cycling on and off, and then go drive it.

 

i just had the same problem and i was baffeled.. I finally noticed that. Coolant was leaking from my waterpump and my thwrmostat was sticking closed.. That is why the hose on the thermostat side was cold..i replaced it all itsan easy job if you have thetiming belt tools... Make sure u have them so u dont run into the timing problems i have now

 

If the engine ishot and u have a small leak u will never zee coolant if its leaking from the pump... It will burnup as it comes out

 

The t-stat can be removed with the t-belt in place. Of course it's moot if you're doing a water pump

 

But you might have to take the plastic timing belt covers off. Typically, there can be so much grime on an engine that a small coolant leak will go unnoticed as the leak is just soaked up by all the grime.

Otherwise, an engine block doesn't get hot enough at 195*F to "burn up" coolant.

 

I'd add more but I think Todd covered it all.