Hi
Just got the Daimler 6 out of mothballs for first real run this year. Everything running great except the temp gauge reads very low or not at all. Car was up to temp I would have said. When I stopped for gas the needle crept up, but on the run again it dropped right off.
It was a very cold day with minus winds, but even so, can’t believe it would be that low.
Im not too bothered but will it affect the running, if the brain thinks it’s not hot enough? Could just be the gauge I guess but it does move on stopping.
Any ideas?
Regards W

 

the sender for the gauge is separate from the sender for the engine computer. you will see two sensors bolted to thermostat housing, the one with a single spade connector is for the gauge.

you can check actual temp with a $5 elm327 reader

 

As Xalty mentioned the instrument cluster is the single wire sensor and the ECU engine regulation Temp sensor is next to it as the 2 wire sensor

You observed probably by feel that your coolant is up to temp but the thermostat my be " floating " back and forth on the road

The 2 wire temp sensor has to see 88 degree C to be in the ECU closed loop mode

On the X300 the thermostat doe not take a O - ring , even f it comes with one

A 0 - ring if installed will crack the thermostat housing

The instrument cluster gauge is a dummy gauge and not so much as a arcuate temp response so is not the most confidence building for information

But you have 2 pieces of information pointing to the actual coolant temp is in question

Coolant fluid level correct ?

You do have a fuse to look at and this has to do with the O2 sensors that are warmed up by heaters

The fuse # 14 / 10 amp right engine fuse box covers all your O2 sensors , you may have 2 or 4 O2 sensors

 

Thank you for the reply, when you say the thermostat may be floating Back and forth, does that imply it’s faulty or would that be normal, as I said it was a bitter day.
W

 

The thermostat moves very slowly back and forth to throttle / limit the coolant flow though the radiation to keep the coolant just above 88 degree C

It can be bad and swinging wildly open and closed back and forth and not holding the point just above 88 degree C

 

I wouldn’t say it was swinging wildly, but when I think about it , the temp allways seemed slow to register. I guess I won’t know till I put a thermometer on to see what it really is! Where would you put the thermometer on to test it. The block or the thermostat. My experience was from younger days, that an engine block or water system should be just too hot to leave your hand on, just like a domestic hot water radiator, which usually runs at about 90C.

 

Usually the hose going to the radiator as it should have some flow if the engine block is up to temp

To improve the response on the instrument gauge remove the single wire sensor and sand the tarnish from the copper crush washer and the seat on the housing

This is the ground path for the sigle wire sensor

It will be pressurized with boiling fluid so cooling precautions

 

You have been so helpful, thank you. I’ll check that, but just one more question. If I remove the sensor to clean up the seat, will it leak fluid? I can presumably do it with cooler or cold engine to avoid scalding.
Thank you again, I am very new to Jaguars.
W

 

The only fluid above the sensor would be in the reservoir on the cars left side

There is a easy half turn ( if I remember correctly ) drain port on the bottom of the radiator on the right side

So what part of France ?

 

Ok fine thanks.
I am just North of Bordeaux, ' amidst the vines and the sunflowers'. It’s beautiful but unusually very cold right now. I am English but living here permanently. Love it, a very slow pace of life. Not like the US at all. But I love the US, don’t get me wrong, I’ve spent a lot of time there, my son is on Long Island. you’re in Kansas, don’t think I been there, travelled to most of the US though.
W

 

I rented a car a couple of times to drive around France and crossed through on the way to the Airbus factory

I use to be a jet doctor for American Airlines and Trans World Airlines ( TWA )