The V8 Owners Forum -

I have the EFI inlet manifold as used on 3.9EFI. On the front top left there's the standard rover water sensor which I used for the ECU. On the front right there's another temperature sensor installed in a converter, not sure what was there before. It seems that the temperature is not as stable here or it could just be the sensor. Any ideas?

Here's a picture courtesy of rimmer brothers. As you can see the standard sensor installed on the right hand side in this picture. I have my dash temperature installed in the hole on the front left.

I'm not sure what you're exactly asking. But on the older 3.5's there are 3 senders on the inlet manifold (coolant) :

1 - the gauge (different part numbers depending on model)
2 - ETC8496 - the ecu
3 - EAC1385 - the thermotime switch for cold start - i can't explain it in my own words but here is a link - http://en.wikipedia.org/wiki/Thermotime_switch

All sensors will (should) read the same as it's a common chamber and should be full of coolant.

Hth

Gordon

adamnreeves wrote:I have the EFI inlet manifold as used on 3.9EFI. On the front top left there's the standard rover water sensor which I used for the ECU. On the front right there's another temperature sensor installed in a converter, not sure what was there before. It seems that the temperature is not as stable here or it could just be the sensor. Any ideas?

Here's a picture courtesy of rimmer brothers. As you can see the standard sensor installed on the right hand side in this picture. I have my dash temperature installed in the hole on the front left.

The front horizontal sensor beside the thermostat is for the dash gauge. The
two vertical bosses are for the EFI coolant temp sensor and the thermotime switch. The EFI has its own temp sensor with a dedicated ground, rather than using the engine block. Good practice with electronics.
The thermotime switch controls the cold start injector - not needed with an aftermarket ECU.

I've used the vertical sensor for my ECU and this shows consistent temperature readings. The two vertical holes for are actually not drilled out in mine and I have no need for the thermo switch thingy. The horizontal hole just under this boss is where I have installed my dash switch and this does not show consistent temperature readings. Last night it was saying 105celius but my ECU was saying 93celius. I am now thinking this is not in the coolant and I am reading the temperature of the metal!

That's a sensor fault.

Gordon

Good point, might be. I'll replace it to eliminate the possibility. Thanks.

zim wrote:That's a sensor fault.

Gordon

On my 4.2 manifold (same as yours) i drilled and tapped a hole where the thermo sender is on the 3.5 - next to the ecu's sender. So I now have the standard gauge as well as well as my own mechanical temp gauge. I run my truck with highish rev's, low speeds and rear mounted rad so cooling monitoring is critical as i can't afford to cook it when i'm stuck in the middle of a bog !

G