Overheating Problem

[Lorenz]

Hey guys,
Last weekend I took the car for a good long drive (its been a while) and all of a sudden I looked at my temp guage and it was off the end of the dial (not cool).
Pulled over to let the car cool down, coolant was boiling and spitting out the top of the tank.
Managed to get the car home alright later on after topping the coolant up with water and taking it pretty easy.
When the car gets too hot, the thermos should kick in correct? They were'nt on which was odd as they used to always come on on hot days and never had I seen the temp go over the half way mark....
Car runs fine, but seems to heat up a lot quicker than it used to and if Im driving around long enough, it will go over the half way mark and keep rising.
Thermos still arent coming on (guessing the themostat is stuck or the switch is broken?) and Im a little worried that its getting so hot to quickly.
What else do you think I have broken or damaged? Water pump?
Before I take it to someone else to have a look at, thought I would see what I can get from on here. Willing to change over a few parts if need be, already priced up a replacement pump and thermostat (about $100 delivered from US).
Appreciate any help
(It's a 2.0L 8V btw!)

[gldgti]

thermostat. if its shut, radiator wont even heat up (thats where the thero switch is) and the engine will get really hot fast.

get a new 'stat, stat

[Golf Loon]

Radiator fan switch.
Try disconnecting the 3 wire connector to it and bridge it out with a wire, if the fans come on then, but not when car is hot, I would change the switch.

[Lorenz]

Thanks for the quick replies guys. Will give it a go tonight and see how we go

[Lorenz]

Had a play around before, hard wired the thermo's but still no difference. I think the thermostat is buggered, top rad hose is hot as, bottom one is stone cold so getting no flow unless my rad is bloked (which I doubt....)
Any other ideas?

[gerhard]

Take the thermostat out and take the radiator hose off the top, start car and see if the pump is pumping.

Drop the thermostat into boiling water and see if it opens.

Then you'll know two critical things. If they both are OK, check the radiator for blockage.

[Golf Loon]

Or the waterpump has no fins left.

[tommymac]

ouch, yer my guess is thermostat, unless you changed your coolant recently and have a massive air lock, which I doubt. If the rad is cool then it wont be your thermos, earth the switch to see that they def work. top hose hot bottom hose cold to me means thermostat. when you get a new one drill a 1mm-2mm hole and mount it as 12 o clock to help with any air locks.

[Lorenz]

Thanks for the help again.

Ordered a new thermostat, will pick it up later and hopefully get it in this weekend