Hot - hot - hot... errr HOT!

[mackat]

Now the weather is cooling down, it's kinda nice to have a toasty car - With the exception of the Astor were I now get a free sauna every time I drive it.

Coolant level is fine, pulled the brown plug and both fans kick in on high, but never seem to start when the engine temps reach 90Deg or above.

I managed to do the aircon button hack to turn them on manually, saved me a couple of times driving around London, but the weird thing with that, the temp gauge jumps up 10Deg when switched on before it starts to bring the temperatures down.

I'm thinking maybe its the thermostat, any thoughts?

[powerandtorque]

If the radiator gets hot and using the aircon fan as an over-ride cools it down to the temperature it normally sits at, it won't be the thermostat.

[mackat]

If the radiator gets hot and using the aircon fan as an over-ride cools it down to the temperature it normally sits at, it won't be the thermostat.

Thanks - Next thing on my list of suspects would be the water pump?

[powerandtorque]

When you're travelling along at normal speed, is it running hot then as well?

Or is it only when in slow/stationary traffic and - presumably - the fans not coming on when they're supposed to? If it's the later and unplugging the brown sensor makes the fans work, are you sure that it's not just the brown sensor itself that's dead?

[Ruan]

Now the weather is cooling down, it's kinda nice to have a toasty car - With the exception of the Astor were I now get a free sauna every time I drive it.

Coolant level is fine, pulled the brown plug and both fans kick in on high, but never seem to start when the engine temps reach 90Deg or above.

I managed to do the aircon button hack to turn them on manually, saved me a couple of times driving around London, but the weird thing with that, the temp gauge jumps up 10Deg when switched on before it starts to bring the temperatures down.  

I'm thinking maybe its the thermostat, any thoughts?

How sudden is the jump?

If it's as the load comes on, bet you you've got an earthing problem.

[maxzy]

Have you tried to swap the brown sensor ?

May be the cause of all probs.

[powerandtorque]

The brown sensor is a doddle to swap and if you're quick you can do it without dropping the coolant. Do it with the engine cold though otherwise you risk burning yourself!

However, as Ruan says, the guage jumping about does sound odd and something like an earth issue could well cause it.

I would have thought that if the fans work with the sensor unplugged then the earth side of things should be good enough for the fans to work, but worth checking and ruling out first.

[mackat]

Thanks Chaps!

I think I have another brown sensor floating around somewhere, will hunt it out today and try fitting it tomorrow.

The car comes up to temperature quite quickly, would say 4-5mins of slow driving it's around 70-80Deg
Either normal driving or ragging it I'm looking at 70-80, it's the slow/stationary traffic which is the killer. I've had to stop a couple of times as it was getting uncomfortably close to the red.

I think the jump up on the gauge is probably to do with the aircon button fix, I'd need to try bridging other pins rather than 3-4 to see if that helps.

[Ruan]

I would have thought that if the fans work with the sensor unplugged then the earth side of things should be good enough for the fans to work, but worth checking and ruling out first.

Fans aren't earthed through the engine block though, that's off body electrics. Seen exactly this before where there was a dodgy earth, only other things that would be affected are obviously spark - although it's not a high load thing, very small current, but the main thing is the starter.

[jjenn20]

Wait, is coolent ment to spill out when you undo the brown sensor.
I changed mine and coolent just trickled out.

[powerandtorque]

I would have thought that if the fans work with the sensor unplugged then the earth side of things should be good enough for the fans to work, but worth checking and ruling out first.

Fans aren't earthed through the engine block though, that's off body electrics. Seen exactly this before where there was a dodgy earth, only other things that would be affected are obviously spark - although it's not a high load thing, very small current, but the main thing is the starter.

Fair enough if you've seen similar before.

My way of looking at it is that if the engine earth is good enough for the starter to crank over strongly (ie passing a significant amount of current) and the engine runs cleanly (so the sensor return should logically be relatively "clean") then it should be more than good enough for anything else.


If there's any doubt of course, a jump lead from the battery negative to the engine block should rule it out.

[mackat]

Managed to find the additional thermostat housing, to find it only has the green sensor and blanking caps over the other two holes. Bummer!

So while I'm trying to source a brown sensor, you're thinking it could be an earthing problem?
Anywhere on the block to the battery neg should give me what?