HELP!

Broken down in Hampshire with the problem of the car overheating, and cant figure out why?

The water pump is working.
The head gasket is fine.
The heat varies depending on the speed and hill gradient.

My girlfriends dad thinks one of the fans might be dodgy or the thermostat is stuck open.

Any ideas or questions?

Couple of starting points;

Expansion bottle cap - these fail and don't keep pressure so your water boils

Air lock in the cooling system - Have you bled the system from the three bleed point - Radiator, engine bay bulkhead (from heater matrix) and engine bay metal cooling pipe just forward / below throttle body.

Are you losing coolant?

Check the fan fuses. The relay for the rad fan is the yellow one next to the under bonnet fuse box. You can bridge the connections to give constant power the rad fan. I've got a photo somewhere...



With ignition on disconnect the sensor above the expansion tank. The bay fan should run.

The coolant is boiling in the cylinder without the cap off.
and i haven't bled the system.

we think the fan is running from what we have heard, but (i broke down last night) when we limped it home for a hour last night the fan didnt seem like it came on or off when the temperature raise or fell.

Check the fuses etc Fuse 6 under the bonnet, fuses 5 and 15 under the steering wheel.
As for the thermostat it would only overheat if it was stuck closed. Check the rad and underfloor pipes for temperature when the car starts to overheat. If they are not red hot then suspect the thermostat is stuck closed..

this is the sensor to disconnect for the bay fan.

I presume it's an F, not TF

Is the rad fan running? Check the fuses; Fuse No. 6 in the under bonnet fuse box and on an F and the fan relay is just outside the fuse box.

You can force the fan to run by pulling the relay out and putting in a link wire to test it (image below) If you have checked the fuse and it's OK with the link wire in the fan should run.





If the fan runs by the method above then re-fit the relay and go for a run, get the engine up to normal temp then leave it idling, the temp will rise due to no air flowing through the rad and the rad fan should cut in after a few minutes.

If the fan will not cut in than have a look at the sensor switch, this is fitted at the water outlet on the cylinder head, exhaust manifold side, flywheel end. There are 2 switches/sensors on the outlet, the lower is for the gauge in the dash and the upper sends a signal to the engine ECU to switch on the fan (at just over 100 degrees C) Pull the plug on the sensor and clean the terminals.

If the fan runs as it should but it's still overheating check or replace the expansion bottle pressure cap, if it's not holding pressure the coolant will boil at a lower temperature.

Good luck and let us know how you get on.

Brian.

I will check all this when my gf dad gets home about midday and keep you guys posted. And thats what i meant! :oops:

Badger wrote: I presume it's an F, not TF

Is the rad fan running? Check the fuses; Fuse No. 6 in the under bonnet fuse box and on an F and the fan relay is just outside the fuse box.

You can force the fan to run by pulling the relay out and putting in a link wire to test it (image below) If you have checked the fuse and it's OK with the link wire in the fan should run.

If the fan runs by the method above then re-fit the relay and go for a run, get the engine up to normal temp then leave it idling, the temp will rise due to no air flowing through the rad and the rad fan should cut in after a few minutes.

If the fan will not cut in than have a look at the sensor switch, this is fitted at the water outlet on the cylinder head, exhaust manifold side, flywheel end. There are 2 switches/sensors on the outlet, the lower is for the gauge in the dash and the upper sends a signal to the engine ECU to switch on the fan (at just over 100 degrees C) Pull the plug on the sensor and clean the terminals.

If the fan runs as it should but it's still overheating check or replace the expansion bottle pressure cap, if it's not holding pressure the coolant will boil at a lower temperature.

Good luck and let us know how you get on.

Brian.

Obviously a lot of info as above came in while I was getting some info; sorry for the duplications. Brian.

So it turns out it was the head gasket, well that's what we think. Its getting checked by a friend soon to confirm but as this is my first one i don't really know how to go about it in terms what head gasket i should get etc. So anyone wanna give some handy tips?

Thank you!

by the way its a 1.6

Give Russell from MGRoverSolutions a call - persevere he's not an easy man to contact sometimes - but he'll sort you out. He got my 1.6 Sunstorm working after it had been botched by a previous garage who took it apart and left it in bits!