Gs300 Overheating

[yusaf1]

Hi, our gs300 has started to show hot on the inerior temp guage and when the bonnet is up is clear to see that the water in the expansion bottle is burbling away.

It also seems to take a while for the air through the blower to get hot though??

The fan infront of the radiator comes on initially at startup, is this correct??

I am wondering if it could be the thermostat or temp switch??

Any ideas??

Thanks.

[TigerFish]

Have you tried topping up the cooling system, is it low on coolant?

I wouldn't expect to see bubbling in the expansion tank if the thermostat was gone. You can normally tell if the thermostat is stuck shut if when started from cold, if once the engine shows normal temp on the guage, does the radiator then feel hot. If it is stuck shut, hot water won't get routed to the radiator and the rad will feel cold/cool to the touch for a long time after initial warm up.

On my mk1, bubbling in the expansion tank as a result of a blown head gasket, hopefully that won't be the case here though.

[yusaf1]

It's not low on coolant.

I'll start it up and see how long it takes for the rad to get hot.

I'll check the dipstick to see the oil condition.

Is it normal for the radiator fan to operate from start up from cold?

[TigerFish]

Isn't the main cooling fan a viscous coupled one on the mk1 GS? In which case it probably will spin up. Any other fans will be for the aircon, so make sure that is switched off if testing any other fans (been a long time since I've been under the bonnet of a mk1, so the memory is all a bit hazy).

[yusaf1]

I've checked the dipstick and the filler cap and no signs of water ingress so I hoping that it is not a head gasket issue.

When we ran the car up the interior temp guage went up to the middle fairly quickly but the radiator stayed cold and the top hose was easily squashed with no signs of any water travel. I also did this with the expansion bottle top and radiator cap off to see if there was any airlocks.

I told this to my local garage and they are suggesting it could be the water pump??