urgent help needed, overheating badly

[justin3779]

hi guys ive got a mk3 2.0 8v gti which has run absolutly great until last week when it started to overheat really bad. the temp gauge is going to the top and the oil temp is going through the roof as well ( it hit 120 yesterday ) the rad seams fine and the fan works but its getting that hot its blowing steam. i had the plugs out out checked the cylinders and theres no water so the head gasket aint gone. i couldnt find a thermostat either. anyone got any ideas ?

[Deano2711]

If you want to check the thermostat then let the car warm up and when the fan kicks in then check the two radiator hoses. The top one and bottom one should be hot. If the bottom hose is still cold then the thermostat is not opening and needs replacing. Just don't let the engine get too hot 

[lord14]

to check teh thermostat you be able to takem it out and put it in a bowl with boiling hot water
. then it will open up once it reaches a certain temperature , if not its broke

[justin3779]

do you think it might be the water pump ??

[Deano2711]

Coud be the water pump Mate but check the thermostat first as this is cheaper. Also try driving the car with the coolant reservoir cap off. If yours has the Blue cap then these are prone to fail and the Black caps are more reliable. Always try the cheaper easier stuff first 

[justin3779]

i dont get it ? how can the bottle cap affect it, cos it is a blue one

[Deano2711]

i dont get it ? how can the bottle cap affect it, cos it is a blue one

Not sure how they differ Mate but heard a few stories of the Blue one failing. If the rubber seal inside fais then the pressure system is not right and believe it or not it does have an effect. Try driving it without the cap to relieve the pressure and see if it makes a difference. It's a free test and may work or may not 

[sharki786]

I thought the black caps were bad and the blue one were ok?

[Deano2711]

I have always stuck to Black caps and never had a problem. Maybe someone else can confirm which way ??

[rubjonny]

its the black ones which are early, blue ones were the replacment. but i believe its the mk2 pre-90 caps that the design actually changed black to blue, from what ive seen the mk2 90spec + mk3 caps are very similar black to blue. if the system isnt sealed then the coolant may boil, and if that happens you get airlocks in the system.

have a read:
http://www.golfgtiforum.co.uk/index.php?topic=106380.0