XJ40 4.0 low coolant sensor

[Oldbaldbiker]

Hi all,

Just joined, as just purchased 2 XJ40’s. Only had Ser 1,2 &3 before, apart from a V8 250.

The dash light for the low coolant sensor is showing on my 4.0. Is there any way of testing the sensor to see if it is actually faulty? Are there any workarounds or repairs that can be done to these, rather than purchasing a new one?

Still trying to work out how to post a picture!

Cheers

Chris

[xj40 paul]

Try this link if its working , its what I came across in my 1988 40 , regards Paul .

viewtopic.php?f=23&t=998692#p186489

[stevemc]

Try this link if its working , its what I came across in my 1988 40 , regards Paul .

viewtopic.php?f=23&t=998692#p186489

its working

[naki_k]

Try this link if its working , its what I came across in my 1988 40 , regards Paul .

viewtopic.php?f=23&t=998692#p186489

Those are specific to the 86-89 models.
90-94 3.2/4.0/6.0 use a entirely different part.

I would suggest removing the sensor. It’s on a bayonet fitting. They are quite fragile though. You may find it’s actually broken in two already, or obviously damaged in some way.
Do check the plug and wiring too, to be through.

I have spares here if needed. PM for details.

[katar83]

I bet it's the bit in the tank itself that fallen out or is stuck

[Oldbaldbiker]

Thanks for all the advice - will check them out tomorrow. Can I remove the sensor from the tank, keep it connected and immerse the sendor in a container of water to see if the light goes out?

[xj40 paul]

Try this link if its working , its what I came across in my 1988 40 , regards Paul .

viewtopic.php?f=23&t=998692#p186489

its working

Nice one steve , that's the first ever time I have forwarded a link on here & didn't know if I was doing it right , I'll try posting a picture next & see if I can bugger that up

[naki_k]

Thanks for all the advice - will check them out tomorrow. Can I remove the sensor from the tank, keep it connected and immerse the sendor in a container of water to see if the light goes out?

I do not think it’s that simple. I think there’s a float and magnet set up inside the tank that this sensor reads off. When you remove it you will see what I mean.

[katar83]

Correct. There is a float inside the tank with a little magnet thingy. Its possible the sensor itself came off the tank, mine did it few times but like I said sometime the little magnet or float inside comes off its resting place and you'd have to be very lucky to get it back in there without splitting the tank. In that case its usually easier to replace the whole tank.

[Oldbaldbiker]

Hi all,

Many thanks for all the helpful suggestions.

Just an update: While the warning light comes on initially, it now goes off once the engine reaches normal operating temperature. Not sure if this is normal, but am happy to live with this!

Next task: fixing the blower motor, which is not blowing at low or medium speed - found a really good step by step instructions on this site!

Cheers

Chris