MontyChambers

MontyChambers

Member
This I hope will be straightforward:
My 2.5 diesel will not warm up, stays around 45c.
So I want to test/replace temperature sensors. Having not taken a spanner to her yet I want to know the procedure to make this task as economical as I can time wise.
If someone could tell me where to start I would be very grateful.
Kind regards John
 
Start up from cold and see how long it takes the radiator to warm through. It'll get hot at the quickly as normal but if it starts blowing warm air from behind the fan quickly it could be an open thermostat. Watch your fingers😜 run for about fifteen minutes, the coolant pipe on the right hand side should be cooler than the left hand coolant pipe.
 
Last edited:
Thanks Allan
So I should change the sensor.
It’s located towards the front of the engine near the injectors? Should I remove the alternator to reach it?
What would be the best way to go about this?
 
It would either fix the problem or eliminate that part form the diagnosis. I have a new one anyway. What I want to know is where should I set about getting to the sensor by the injectors toward the front of the engine head.
 
If you want to change the sensor also you go via the inlet manifold. Disconnect battery (standard procedure) Intercooler ducts off, Inlet manifold off. This is simplified there will be gremlins along the way like spill pipes to remove, brittle wires, possible snapped threads etc. later plastic manifold will be a little easier. Once you remove the sensor you’ll let air into the block so you will need to suffer bleeding that out too.
Have a look through RAVE to familiarise yourself first
 
RangeRoller dt said:
If you want to change the sensor also you go via the inlet manifold. Disconnect battery (standard procedure) Intercooler ducts off, Inlet manifold off. This is simplified there will be gremlins along the way like spill pipes to remove, brittle wires, possible snapped threads etc. later plastic manifold will be a little easier. Once you remove the sensor you’ll let air into the block so you will need to suffer bleeding that out too.
Have a look through RAVE to familiarise yourself first
Click to expand...
Thanks, that is what I needed.
I will flush the cooling system while I’m at it!
Ta very glad 😃
 
You state that it stays around 45ºC, how do you know that? If you're guessing that's an odd statement to make. But, I rather suspect that you're getting that data from a couple of potential sources:
1 - Diagnostic from the ECU in which case, the sensor is working just fine.
2 - Infrared or analogue thermometer in the coolant.

A cross reference of these two will be that either the coolant temp is physically low and agrees with the gauge or the ECU in which case the sensor is working just fine, or, the coolant is up to temp (at a guess somewhere around 90ºC) and the gauge doesn't agree in which case I would take the plug off the sensor and earth it to see if the gauge goes fully to the red indicating that everything but the sensor is in working order.

It seems as though you're dead set on changing the sensor, let us know how you get on.
 
Blob said:
You state that it stays around 45ºC, how do you know that? If you're guessing that's an odd statement to make. But, I rather suspect that you're getting that data from a couple of potential sources: 1 - Diagnostic from the ECU in which case, the sensor is working just fine. 2 - Infrared or analogue thermometer in the coolant. A cross reference of these two will be that either the coolant temp is physically low and agrees with the gauge or the ECU in which case the sensor is working just fine, or, the coolant is up to temp (at a guess somewhere around 90ºC) and the gauge doesn't agree in which case I would take the plug off the sensor and earth it to see if the gauge goes fully to the red indicating that everything but the sensor is in working order. It seems as though you're dead set on changing the sensor, let us know how you get on.
Click to expand...
Blob said:
You state that it stays around 45ºC, how do you know that? If you're guessing that's an odd statement to make. But, I rather suspect that you're getting that data from a couple of potential sources: 1 - Diagnostic from the ECU in which case, the sensor is working just fine. 2 - Infrared or analogue thermometer in the coolant. A cross reference of these two will be that either the coolant temp is physically low and agrees with the gauge or the ECU in which case the sensor is working just fine, or, the coolant is up to temp (at a guess somewhere around 90ºC) and the gauge doesn't agree in which case I would take the plug off the sensor and earth it to see if the gauge goes fully to the red indicating that everything but the sensor is in working order. It seems as though you're dead set on changing the sensor, let us know how you get on.
Click to expand...
Blob said:
You state that it stays around 45ºC, how do you know that? If you're guessing that's an odd statement to make. But, I rather suspect that you're getting that data from a couple of potential sources: 1 - Diagnostic from the ECU in which case, the sensor is working just fine. 2 - Infrared or analogue thermometer in the coolant. A cross reference of these two will be that either the coolant temp is physically low and agrees with the gauge or the ECU in which case the sensor is working just fine, or, the coolant is up to temp (at a guess somewhere around 90ºC) and the gauge doesn't agree in which case I would take the plug off the sensor and earth it to see if the gauge goes fully to the red indicating that everything but the sensor is in working order. It seems as though you're dead set on changing the sensor, let us know how you get on.
Click to expand...
 
Hi Bob
I am new to this so if I am coming across as a bit thick it’s probably because I am.
I use a thermometer with a red dot and point it at various places:
Low down on the engine block gets to 45-50 max, after an hour ticking over. The metal intakes to the radiator are 24 one side and 30 odd on the other.
I have gotten confused with sensors and the thermostat!
It is clear now.
I will remove the fan, rad, till I can get at the thermostat, which I will remove and test with hot water.
I will them replace thermostat and pipes with new. Check the condition if the rad and fan, rebuild and test.
I will post the results.
 
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