i went to look at a mk3 2.0 8v gti yesterday for a friend and during my simpleton check i noticed that there was hardly any water/coolent in the header tank at all and that there was a redish rusty colour deposit inside the reservoir. Ive heard in the past that if you dont use the vw coolent in certain rads it can lead to corrosion, is this what has happened? if so is it a new rad or is the head gasket on its way out. there was no mayo in the filler cap and the car didnt over heat when idling or on the test drive. Any advice would be greatly appreciated as its a solid little car and im desperate to get the rover man into a vw as is he!
all coolant has anti corrosion properties, however the VW one is the recomended for the car...(ive never bought it) i think the VW one is for long life service - unsure. the red you are seeing is deposits of the oxidisation of the cylinder block, perfectly normal when a few coolant changes have beeen missed - regular flushes and coolant changes will prevent your water getting brown, dirty coolant has less cooling properties than clean coolant. the radiator is generally a mixture of aluminium/copper bars/fins and polymer end caps (tanks) certain coolant may harm it quicker than others - i cant see how they can possibly sell aftermarket coolant is it was detrimental to any component. the thing with red water, it has particles in it that will deposit and block a rad over time (in the case of our lil corsa diesel work horse 11 years with no water changes caused it to block). when you view a car with coolant like this you need to be aware that the maintenance and serviceing may not have been kept current so this may not bee the biggest snag on the car. however you can be quite confident that no one is trying to cover anything up such as oil in water. you need to run it up to temp and wait for the fan to switch on a few times to see if it boils, at all times squeesing hoses etc to check for exessive pressure. if it all checks out ok - get it home, flush it out with the hose for a few hours then refill with proper coolant be it VW recomended or aftermarket poop.
