P38 Diesel temp gauge - where should it be?

Hi - Our DSE temp gauge rarely moves from just above the blue end of the scale. Unless we're pulling up a long hill or something then it has been as high as half way.
I've had a few 525TDS Bmw's and I know the thermostat is bit of a weak point. The whole plastic thermostat housing is rubbish, the cheap plastic lugs that hold the thermostat itself break so the unit can't open and close correctly. Its a minor fault that causes big probelms.

Anyway, can someone confirm that the temp gauge needle should sit in the middle all the time (like the BMW TDS's does) or is it normal for it to sit in the first quarter?

Thanks
Richard

Mine is the same, I suspect a stuck open thermostat, and I'll get round to replacing it one day if I can get the viscous fan off...

Its normal, even when a replacement thermostat was put in it still read low.

Mine will stay just into the white section most of the time. When its warm it will rise to just under 12. When I was in the peak district and going up a long hill that was the only time I've ever seen it sit at 12 and stay there. As soon as I got to the top and was on a level again the temp started coming back down. I wouldn't worry about it. Better under than over 12 o'clock

-Wills

Morning RSW

i had a similar problem with mine
The needle would seldom go much above the blue sector on the temp gauge I too suspected the thermostat beening stuck open looking at where the thermostat location was and the circus to get at it decided to lag the radiator (ie reduce the cooling area on the radiator) this i did by cutting a cover to g behind the intercooler in front of the rad and leaving a circular cut out in the middle about 35-40 cm across
in my case it did the trick the motor warmed quicker and stayed in the middle of the gauge
eventually i was going to install a kenlowe (electric) fan and then do the whole lot as i suspected the viscous fan was sticking.
-Thermostat replacement
- Viscous fan removal
- Electric fan instalation
this was done about a month ago and all seem to be well - the vehicle warms up quickly and the fan can be set to kick in at whatever broad temp you dial in on the accompanying adjustable thermo-switch
in short i would suggest lag the radiator - in my case is used freely available cushion flooring with a held in place with a wooden bead to which the material was attached the width of the rad to avoid the material falling down between the intercooler & rad
hope the info helps

Mine sits just a tad under 12 o'clock....all the time once warm, regardless of what the car is doing, flat out or idling, I have a brand new radiator, waterpump, and thermostat, I've also flushed the block and made sure all the hoses are clean, the coolant is 50/50 mix, the car warms up from cold in around 2 mins of normal driving.

I know the gauge works fine as when my old engine destroyed it's head the gauge was often off into the red zone with the little light on!!!

From what you describe it does sound like a stuck open stat.

Mine is also just about always in the blue, only rarely goes hot when pulling the big trailer over the moors, then the fan cuts in & it whizzes back down again.
If your stat is stuck open, it will take forever to get any heat from the heater, as the entire system is flowing & the engine is slow to warm up, if the stat is working correctly, then its shut to begin with, the coolant is confined to the block only,so the engine warms quick & the heater will as well, mine starts chucking out heat before I get to the end of my road, & thats at 0600hrs!!

Thank you all very much for the advice and general feedback. Some good advice and top tips, I'll give them some thought.

Just as a part reply I find the best way to remove that fan is to stick a spanner on the fan nut and belt it anti-clockwise with a hammer. Sure the fan turns but give the spanner a few swift clouts with a hammer and it spins off.

Thanks very much
Richard

mine used to be low until I fitted a new thermostat, it too used to warm the heater up quickly but the guage never showed very high. I changed the stat and it now sits right in the middle once warm and stays there regardless of load or speed. It's now doing exactly what it says on the tin and it maintains and regulates the temperature.

I finally got round to changing the thermostat on my DSE today, and now it works a treat! Previously it used to stay just out of the cold zone, only moving up under heavy loads, but now it shoots up to 12 o'clock and stays there. Incidently I checked both old and new thermostats in boiling water and both opened up as you'd expect, so maybe the old one was opening at too low a temperature.

I also cleaned out the intercooler, intake manifold and all pipework of sludge accumulated over the vehicle's lifetime. The driveway is a bit of a mess but it's made a definite difference to driveability. I also added some wire gauze into the hose between the rocker cover and the intake duct, as I reckon this is where the oil sludge comes from, the gauze should trap the oil being sucked out of the rocker cover and keep things cleaner.

My temperature gauge like most of the posts on this thread stays mainly in the blue.

I have been having problems with the needle lift sensor (so the land rover garage computer says). As mentioned in other threads this results in loss of power and engine management light flickering on, change down a gear and problems goes away. so I replaced the needle lift sensor but the problem still seems to be there. :doh:
It does seem more noticeable when the weather is cold or from a cold start. On a long run it very rarely has a problem.

Could the two be related? Is the engine choking itself thinking it is still cold.

Thanks all.

The engine will be running rich if the ECU thinks the engine is cold all the time. Always fix the obvious problem before looking for the complicated.

lanmjdun said:

Mine is the same, I suspect a stuck open thermostat, and I'll get round to replacing it one day if I can get the viscous fan off...

Click to expand...

Problem with that statement is that waxstats NEVER stick open. They always fail shut.

wammers said:

Problem with that statement is that waxstats NEVER stick open. They always fail shut.

Click to expand...

I agree with that in principle, but I have seen stats jammed open by bits of debris. I have also seen ones that have been "doctored"