Temp Gauge / Hot Air Not Working

[jadedsancho123]

Hi guys,

Before starting please forgive any ignorance on this subject, I'm both a newbie to the Rover 75 and this (fantastic) forum.

I have just bought a 1.8 (non turbo) Tourer and upon driving it home noticed that the temp gauge wasn't increasing and there was no hot air in the cabin from any vents. Perhaps mildly warm air blowing when the car is idling/in traffic but nothing when on the move.

I have checked the coolant fluid level, which seems fine, and have just run the car in OBC and readings are coming back in the display which makes me wonder whether my original assertion that it was the Coolant Temp Sensor (which I've just ordered) is unlikely to be the cause. Surely if the OBC can detect the readings then surely the sensor is doing its job?

FYI - the engine fan kicked in at around 40 degrees and Ive been told that the head gasket has been replaced with the uprated version.

What are the other likely causes / things to check?

Really would appreciate any help.

[T-Cut]

Originally Posted by jadedsancho123

- - - this (fantastic) forum.

OK you're in. Welcome to the circus.

I have just bought a 1.8 (non turbo)

What's the car's year and mileage?

FYI - the engine fan kicked in at around 40 degrees .

So somefink ain't right.

TC

[jadedsancho123]

The car is a 2003 with 48k. I've just taken it out for a 20mile spin with OBC and on the move the engine temp is reading between 52-54 degrees. This jumps to around 62 degrees when stood still. I'm guessing these temps are probably about right considering the coolant wont be at boiling etc.

Also, the guage does appear to creep up to quarter temp on first starting the car and letting it idle for a bit. At this time, hot air is coming through into the cabin as it should.

The signs appear to be simialr to other threads I've read, which have idenitifed the problem as a fauly sensor but, as I say, I can't see why the OBC would give a dymanic temp reading if it was this - surely the OBC and temp gauge/hot air systema are related to the same sensor?

Cheers

[T-Cut]

If the OBD readings are correct, the engine is running way too cool. It should be typically around 95-100C for local driving. After a good run, open the bonnet and check whether the upper hose from the head is too hot to touch or just warm. If it's only warm, then the readout is obviously true. If that's the case, it looks like the thermostat is stuck (open). Just to be sure which type you have, can you check the same coolant hose leaving the right end of the head. It goes to the top left radiator elbow (these are as you face the engine). Is there a plastic T-piece in the hose just behind the radiator, with a large bore pipe going vertically down? Alternatively, is it just a simple through connector with no branch?

As to the radiator fan cutting in at 40C, that's not an engine cooling signal. It's possible that the fan is faulty and you had actually tripped the aircon emergency cooling. To check the fan, ensure aircon is off (Econ). Press the Demist button with the cold engine running. The fan should start within a couple of seconds and run continuously until Demist is turned off. If the fan doesn't start for a while, then pulses on/off every 30 seconds, it's faulty. This needs to be addressed separately. Hopefully it will be just the slow speed resistor that's blown. Check for the presence of a resistor behind the fan blades.

TC

[jadedsancho123]

Wow, fantastic reply, thanks so much! I will look into your suggestions over the next couple of days and let you know how I get on. You've been a big help already!

Thanks again