I have previously posted a mod I did to my car which involved fitting a BMW E34/M3 coolant expansion tank. The tank is almost the same but it has the advantage of having a level sensor fitted. Can't recommend more strongly having a coolant level sensor. It saves a lot of grief.

Anyway, to cut a long story short, I was just on the Island4x4 webside ordering yet more bits and low and behold, someone now makes a level sensor which directly replaces the screw cap on the p38 OEM tank. The BMW tank mod is no longer needed, stay with the p38 tank.

https://www.island-4x4.co.uk/expansion-tank-with-sensor-britpart-prc7925-p-8067.html

Can't go wrong at that price even if it is Britpart.

That looks like a great idea. Where do you plug it in? :)

Ooh, sounds good. I think you just volunteered to be our pathfinder Morat :-)

Lol, well I'm sure I can handle replacing the lid - I'm wondering where the signal from the level sensor goes.

It won't work on a P38 header tank. That's a cap for the header on a Classic which is a simple plastic tank and the cap doesn't have the extension with the O ring that keeps the outlet from the radiator bleed separated. This https://bearmach.com/expansion-tank-suitable-for-all-200-and-300-tdi-diesel-engine-v8-and-mpi-vehicles-black-version-esr63 is the header tank used on a Classic, Disco 1 and Defender .

I have already added it onto my order, so hang fire guys. I will let you know if it fits. If it is the wrong one, I will send it back.
It does say it fits all Range Rover 2.5 diesel and V8 models.
My existing BMW expansion tank is wired to an LED in my dash panel. I used a redundant window in the black panel at the bottom of the dash.
Had to reverse the action of the sensor with a relay since the action is high level normally closed/low level normally open. The opposite way you want it.

I'd remove it from your order, the cap won't fit, mainly because the float won't fit in the P38's expansion bottle.

The expansion tank and cap was the same for the RRC Diesel and Petrol hence the "fits 2.5 and V8 models"

I've got a feeling the cap thread is a smaller diameter too so it won't even screw on. If you look at the Island listing it shows it as a Disco 1 part and not a P38 part.

Yeah, doesn't say p38 in listing.

That'll be for the 2.5 VM motori diesel engine and later 200 and 300 tdi range rovers.

I have asked them to knock it off the order.
I will stick with the BMW one:

I have mine to install when the weather loosens up a little.
Tank part number 17111712641, sensor part number 61311384739, and I got a plug for the sensor from a breaker.
Will make photos :-)

I don't have a proper plug for the sensor unfortunately. I have also moved the relay since then. I didn't like where it was.

Do as I did ... take your sensor and go around BMW breakers (if any specialized in that in your area), if they know their biz they will recognize it and just snip the cables with the plug. Should cost you next to nothing, nobody wants or needs such parts :-)

Island4x4 delivered the level sensor even though I told them to knock it off the order.
I can confirm that it is the wrong one. It is for a classic.

Yesterday messing around in the area where I need to pass with the cables for the aux battery and instruments (another post will follow) I thought to clean up a little and mount the BMW tank with the sensor I've already had ...
While it fits no issues, I noticed is missing the extra plug that goes to the throttle body heater ... any workaround you guys might have? Or should I ditch that circuit entirely?
For now - since I needed to move the car out of the workshop and back into its ... resting place, I just fitted a large enough bolt :-)

I think the BMW header tank only works with the Diesel?
Went for an alloy tank with level sensor from Allisports, plug and play.
Have fabricated the LED for the instrument cluster a few days ago by removing the electric contacts from a genuine build holder and drilling an appropriate whole for ease of installation.
Will integrate a buzzer as well, like belt and braces ;-)
Dave3d ... did You use an existing / non-used Icon or did You drill a whole or scratch the black layer. I have a spare instrument cluster which has no unused symbols, so I tried to scratch my own, which looks OK. Will have to look, what's fitted in my car.

Leolito, IIRC you are in the Phillipines? You might not need the TBH there. I wouldn't ditch it here in Canada.

If a V8, why not use the diesel glow plug light. You know what it means which is the important thing and minimum fabrication required etc.

@Harv .... no man, I am right in East Europe, Continental weather ... so far is hot and torrid, but soon (long) winter will set in ....
I can try to run it without and see what happens, which I do not think is a problem ... just some hiccup on start up might be it. Earlier versions of the venerable RV8 did not have this gadget, didn't they?

Sorry to misplace your location. I've read a lot about deleting the TBH on Discoweb. Some guys have had no issues, while others have had their throttle bodies ice up while cruising along the freeway.