XSeries-forum

[quote="henrym3"]
As you say "if it ain't broke don't fix it" but yours is broke and needs fixing. Your car will run forever with an open thermostat,  but it's taking longer to warm up and it's using more fuel, it's just not as efficient.
[/quote]

I've noticed that the cabin heater is not as warm as usual - presumably if the engine temp is running lower then it is likely that the two issues are linked and replacing the thermostat should sort the air temp of cabin heater?

Smee

Without a doubt. Then you'll be snug as a bug in a rug

Not had a chance to book it in yet. Hopefully before Christmas. It was the cabin heat that that did it for me. Seemed to be coming through in waves. That or it's the male menopause.

[quote="henrym3"]
As you say "if it ain't broke don't fix it" but yours is broke and needs fixing. Your car will run forever with an open thermostat,  but it's taking longer to warm up and it's using more fuel, it's just not as efficient.
[/quote]

Ok, so ......the thermostat has been replaced, as had the radiator, the fan and the coolant (but that's s tory for another day). Car has been run for two hours and the hidden menu says the running temp is 58c!

So I think that it is ...
a dodgy thermostat?
coolant sensor on the blink?
There is a secondary thermostat somewhere - anyone know if there is one on 2004 E53 2004 3.0 D auto?

Smee

The E53 has only one thermostat to my belief, my E83 X3 has the same engine but has the DPF and EGR cooler, it only has one thermostat, but the 3.0 SD of the same age has an EGR thermostat. Mine has a vacuum operated valve that operates the EGR flow instead of an EGR thermostat.
As. The E53 3.0 d is euro 4 it wasn't fitted with an EGR cooler, so only needs one thermostat.

Ok thanks, so presumably there is coolant temperature sensor somewhere

Coolant temp sensor is either in the thermostat housing or the engine block

Thanks. The thermostat housing was replaced at the same time as the thermostat, but still showing cold, so must be somewhere else - anyone else know where it is or how i find out?

I guess I could test if it is the sensor by testing the temperature of the water by unscrewing the filler cap when the engine is warmed up and insert a temperature probe?

Careful Smee, if it is a dodgy sensor and your coolant is at the right temperature you could get scalded.

Indeed, ad thanks for the warning, however Ive thought about it further. it can't be the sensor. last week the temp reading on the hidden menu were very low at around 60c so i decided to get a new thermostat fitted. for reasons that I will go into in another post I had a fan problem and the car started to heat up - i accessed the hidden menu and could see the temperature rising rapidly 70,75,80,85,90 etc but managed to get it to the garage

So the coolant sensor was definitely working. We've now fitted new radiator, fan, thermostat and housing, pipes and coolant.

Yet the temp readings are even lower at around 57 or 58c

So what is going on folks?

Where to look next? if I thought the sense was dodgy Id probably just leave it than have it off the road again, but I sense something else is keeping it cold and I want to get to the bottom of that. The only thing I can thing of is that the thermostat that went in is defective (unlikely but possible)? Anything else?

Smell

wouldnt be the air con fan running all the time would it ?  just a thought

possibly. but it's not (running all the time).

If the radiator is getting Warm/ hot before the desired temperature, the thermostat is opening /Stuck too early.
The temp sensor is a thermistor which is a resistor that alters resistance as it heats up. Usually a PT1000
100-1000 ohms
Usually when they fail you will get a set/ unchanged reading , I e been caught out by faulty replacement parts before at work. BMW thermostats fail open, so not to overheat.

Im not getting an unchanged reading it fluctuates around the 58c mark from 56-62 or so