Why is my mk2 overheating?

[Rocco Ben]

My mk2 has been overheating for a while.
Things I've tried: new thermostat. New thermoswitch. New radiator.
My pressure cap is good and my Ignition timing is good. My fan kicks in but not sure if its coming on for long enough.
Any help would be great :)

Ben

[Nate]

have you flushed the entire system through with a hose after treating it with a detergent additive (biological washing liquid is really good for this)

can you see water moving in the coolant bottle to indicate that the water is actually moving round ok?

does your heater blow hot air?

[MikeH]

What he said ^^ plus...

Why do you think it's overheating? Maybe it's just a faulty gauge or sender, if the fan is coming on but not staying on much?

Where does the gauge sit on a run, or in traffic?

Does the bottom hose get hot when it's up to temp?

Does the bottom of the radiator get hot? Be careful not to burn yourself!

If you take the expansion cap off, and start the engine, can you see water squirting out of the little return pipe from the radiator?

[Nate]

Does the bottom of the radiator get hot? Be careful not to burn yourself!

and mind out for the fan. voice of experience!

[Rocco Ben]

When I'm on the road the gauge is to the right and its worse in traffic.
I've flushed the system out. I put my hand next to the fan and the air is pretty hot. I haven't checked if the water is moving.
I haven't felt the bottom hose or radiator yet. I think sensors ok, the engine is deffinately gettin pretty hot .

Ben

[Nate]

sounds like thermostat sticking partially shut, water pump breaking up or cooling system has a blockage or airlock

[eamon1.3]

Ive put in a brand new thermostat into a car and it was still over heating, took it back out and tested it and it was dead, so worth checking it.

[stu.gtx]

Ive put in a brand new thermostat into a car and it was still over heating, took it back out and tested it and it was dead, so worth checking it.

This has happened to me too

[Rocco Ben]

Hmm interesting. I'll try the thermostat again then :) and if its good then o could change the pump.

Thanks for the help lads :D
Ben

[bensspares]

mixture,are the plugs black ??? to rick (unlikley)or too weak pulgs glassed,

my instincts tell me it head gasket if its not the mixture or timming.

check for waterloss and mayo in the rockercover or oil in the coolant resivior.
ben

[MikeH]

It might be that the rad is just old and blocked up. Check the bottom hose is getting hot once the car is up to temp, it should be nearly as hot as the top hose, but not quite.

My '89 scala (the track car) still has its original VAG radiator I think (it's a VAG radiator with a VAG pipe, and the original crimped hose clips) and it's getting a bit warm (150-ish bhp might be part of the issue though).

It's worth checking if your rad looks like it might be original. If it is, could well be time for a change, but as ever, do more diagnosis before you start chucking money around down at the motor factors.

[fonzooorooo]

silly thought, but similar to what the others are getting at:

When you flushed the system, are you sure it ALL flushed? I did mine while I was changing the water pump, so hoses were all off there, thermostat was out, top rad. hose off... that way, I was sure i'd got it all... And I've also had dodgy thermostats.

[DannyH]

you said that the cap is good how do you know this and what colour is it?

the black ones are notorious for causing overheating