Does anybody known how the coolant sensor works ?

I’ve had an intermittent coolant level problem for some months and finally got around to changing the collect expansion tank. In doing so the coolant level sensor popped out of the holder on the new tank. I refitted it but was surprised by what it looks
Like and so am puzzled how it works.

BTW - I followed this excellent video for the method.

Attached are photos of the old tank and old sensor.

Click image to enlarge

Click image to enlarge

Depending on how much coolant is in the expansion tank, the resistance of the probe changes. The car measures the resistance change and flags an error when empty. 2015 Range Rover Autobiography 4.4 SDV8

Many moons ago Nino- Nino bench tested his to prove that not only does it check coolant level but also gives different results depending on the specific gravity of the coolant , thus alarming with water but not antifreeze of the correct mix.

Sorry I can’t remember any more details or find the post.

Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

The probe does not have any physical contact with the coolant fluid. The probe is sited up in to an unsealed tube void in the bottom of the expansion tank, so it’s i’d be surprised if it could be variable resistance based. It might be a magnetic reed switch in the probe (it’s the correct shape for that also) with a float in the tank that operates the reed switch. The float could operate on fluid level but perhaps also operate based on specific gravity of the fluid.

I’m still wondering how / why it could operate intermittently. -------------------------------------
MY 2012 4.4 TDV8

https://www.fullfatrr.com/forum/topic43284.html 2012 TDV8 Black Edition
2000 Disco. TD5
1975 series III

Great explanation. Many thanks for posting the link. -------------------------------------
MY 2012 4.4 TDV8

I now have this problem
So Nino you just cleaned the tank and sensor and re-fitted?

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

It’s quite an easy / cheap job to replace the coolant tank. I don’t think it’s worth removing and cleaning it. -------------------------------------
MY 2012 4.4 TDV8

Thank you, anyone got part number(s) by chance ?

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

This is the one I ordered.

https://www.lrjdirect.co.uk/product/expansion-tank-lr022731 -------------------------------------
MY 2012 4.4 TDV8

amazing thank you bwelton

it looks like it has the sensor in it?

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

Yes, includes Sensor, Coolant Tank and Lid. -------------------------------------
MY 2012 4.4 TDV8

GGDR wrote:

Thank you, anyone got part number(s) by chance ?

.

I got mine from site sponsor Advanced Factors with our discount code AF4LRP  Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
Many, many other Landies over the years
My preferred specialist: www.glenrands.co.uk
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Thanks DrRob

So are we saying non-original is ok in this case?

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

I paid more than twice that price for a genuine one but that was my choice.
If pattern ones are holding up OK without problems then I don't see why not.
How many companies go to the trouble of making such a complicated part? Probably the same ones that supply Land Rover in the first place so we pay over the top for a 'genuine one'.