1993 VW Corrado SLC (VR6) Cooling System

Good post.

It is sometimes beneficial on many models to raise the front of the car as well.

Is there not a Corado forum where the OP can get extra help? Have he/she looked?

I found many in the German language, if you read and write German that is the place to go, but I also found this one in English:-

http://www.autoplenum.de/Antworten/Marke/VW/Corrado

Solar Eagle proposes the best filling technique, you shouldn't have any problems, but if you do; replace the reservoir cap with a new one and inspect all the system for very small leaks, include hoses, radiator fins and all cooloing system joints and couplings.

A small leak will allow an ammount of coolant to be expelled due to the expansion of even tiny air bubbles. During the next warm up cycle, the air volume inside will be bigger, thus the expansion will push larger ammounts of coolant thru a leak.

I've never worked on one of these engines & I have a question . Some of the vehicles we have here in Aussie land have a bleed screw in the system to get rid of air in high areas that the air is trapped in. Do the VW have any thing like this?

Another thought I had is a friend of mine had the same trouble with another type of vehicle & the mistake that he made was that the vehicle wasn't on a level surface the front was lower than the back & even though there was a bleed screw, the air was trapped at the back of the motor & his vehicle over heated until he leveled the vehicle up & then bled the air off & filled the system.

As I said I don't have experience with your vehicle but these are things I have seen in the past so I think worth thinking of.

Hello. Find a sensor,switch or fitting to a coolant passage at or near the top of the engine.Remove same and fill cooling system untill coolant runs out.Reinstall part you removed. Warm up engine and then let cool down to ambient temp. repeat.Hope this helps.

I am no auto expert or somewhere near but i had a similar experience with a japanese model where I could not expel all the air in the cooling system.It turned out to be air from the compression cycle leaking into the cooling system because the cylinder head had had its gaskets burnt when the hose burst.I hope it is not the case for you.

Its actually quite easy to identify such problems as the bubbles will be filled with exhaust gas, not air, just fill the radiator, run the engine on tick over, wait and watch as the bubbles burst and let out exhaust fumes.....air is clear, these will not be clear but "smokey"!

I've owned and maintained VWs for many years. I've done coolant changes on the VR6 engine like you have in your Corrado. They don't seem to require special procedures for filling the coolant system compared to other VW engines. Having some coolant rush back into the coolant reservoir when the cap is removed is normal. And if the coolant is at normal operating temp when you open the cap it will flow back into the reservoir violently. solareagle is correct in his suggestion that your heater core must be allowed to fill during a coolant change by turning your heater control to the hot or heat position. Let your engine cool, turn the heater control to the heat position and fill the system up to the normal level and run the car, try to do this for a while with the heater control in the heat position. During the first fill, when the thermostat opens at about 97 deg. C, you'll see your coolant level drop. This is because the coolant is flowing into the radiator. After that, let the engine cool, check the coolant level, it should be slightly low. Add more coolant to get the level at the normal line on the reservoir. Normally, I have to do this procedure a few times before I get the system full with no air in it. Or I just drive it and check it after every drive until it stabilizes.

Did your engine overheat when the hose failed? Or have you noticed that the coolant temperature is above normal when you drive it? Does your radiator fan run? If the engine is running hot and the system does not leak, when you open the cap-watch out! If the engine is running hot, you need to be sure the thermostat opens and the fan runs (3 speeds). Make sure the belt to the slave fan is ok and that the slave fan turns also. If the engine is running hot the coolant pump may have a broken blade on the impeller and the broken piece may have lodged somewhere in the system reducing flow. Does your electric coolant after run pump work? You can hear it run after the engine is shut down. Lastly, If the engine was overheated, the head gasket may have started to fail, but that is a extreme, and you'd probably be loosing coolant, or worse......