coolant level low warning

[shadow]

hi, dont dont we love these cars ,however has anyone had coolant low indicated on dash warning light when on inspection, ? coolant level is perfect ?

[grahamr]

That's usually the warning switch sticking. In can be can be changed without having to replace the whole assembly

[aaj]

Hi Guys

I have also had this message off & on for the last few months. My local Jag Specialist gave me a working sensor to try. Unfortunately, within a few miles the message returned. Next step new Coolant Expansion Reservoir - £103.18 plus VAT! (but it does come with cap & Sensor) – All because the 10p Float stops doing its job! Be careful when working on the Cooling System as all the plastic parts become brittle & you can get hairline cracks in the components - disturb them & they start leaking.

Regards

Allan

[rtucker]

Hi does any one have the procedure for removing and replacing the sensor and/or the tank, is it posted in the forum

Cheers

Richard

[aaj]

Richard

The following is for the XK8 - I've never looked under the bonnet of an XF

The Sender is a push fit from the bottom of the Tank. It's in a sealed tube set in the Tank so it shouldn't leak when removed (if it does you need a new Tank). It can be removed with the Tank in place.

The Tank is held in place by the pipes & 1 screw you can see from the top (the lug on the side). As well as the pipes you can see there is another connected to the bottom of the Tank - Be careful as there is not a lot of slack & if you pull hard it may drop off the bottom & disappear into the wing void.

Take care when dealing with the plastic cooling parts as they get brittle with age!

Good luck

AllanJ

[rtucker]

Hi Allan,

thanks for the info, it was my XK8 which has the problem. It is 1997 with 100K mile so maybe just old age I will have a look at the weekend following your procedure.

Do you know if the sender is easily available

Thanks Richard

[aaj]

Richard

Part Numbers
MJD4400AB Expansion Tank
LNA5740AB Level Sensor

The part number for the Tank is for the one that only has a pipe going to the plastic Thermostat housing. Earlier XK8's had a second pipe going to the Radiator. The spigot is on the Tank but not drilled out.

One last warning never work on the cooling system when hot as the system generates a lot of pressure & you would not want to get scalded!

I've tried to add pictures of the tank if they don't appear drop me a line & I'll send on (a.a.jones@blueyonder.co.uk)

Regards

Allan

[atticus]

I have just had the same problem of the warning light coming on while the coolant level is good. I have a 2004 XKR and I see the SNG Barrett have both the complete (aftermarket) tank and the (Jaguar) sensor. I would, of course prefer to just replace the sensor and I see from reading the various posts that it is possible to do this without removing the tank, although removing the tank doesn’t seem too difficult. A couple of questions:

Presumably I need to lower the coolant level so I don’t splash it all over the engine bay when I remove the unit, and if so is there a tap somewhere to do this?

What is the thinking on aftermarket v Jaguar parts given both are offered by a reputable supplier?

Thanks

John

[mike020150]

There is a plug at the base of the radiator which can be used for draining purposes. However, for the small quantity in the header tank, it's probably easier to use a syringe. The original header tanks haven't proved especially durable so, in this case, fitting an aftermarket tank may not be much of a gamble. Mike.

[atticus]

Thanks, Mike,

From your response I would guess you would favour replacing the tank, which comes with the sensor fitted?

John

[aaj]

John

I would guess that it's the float that has failed.

After replacing my expansion tank on my MY02 XK8 the 2nd time the float failed again! I gave up with the quality? Jaguar Tank & disconnected the sensor and fitted a short link cable between the 2 connections & just went back to the traditional weekly checking of the coolant level when I checked the oil level.

You can check the Sensor operation with a multi meter and a magnet. Removing the sensor can be done (on the XK8) without emptying the expansion tank. The short cable link would check the wiring.

The tank on the XKR is a different shape but I would guess that it has the same pipe connected to the bottom (see my earlier photos). On the XK8 this pipe doesn't have much 'slack'. I ties a cord to it in case it dropped out of sight.

A number of years ago, there were Chinese copies of the XK8 tank on sale & they failed (fell apart at the seams) after a few months - I assume the SNG Barratt one is of superior quality.

I hope this info is of use

AllanJ

[mike020150]

I think Allan has summed up things nicely. You pay your money ... Sadly however, there are no real guarantees of a quality product. Mike.

[atticus]

Thank you, Allan and Mike for the tips. Yes, The XKR one is a different shape and Barratt’s have this one. I will call them tomorrow and have a chat - Aftermarket or Jaguar, sensor only or whole tank.

[atticus]

Well, I replaced the sensor a with a unit from SNG Barratt. At first I couldn't see how the old one came out so I loosened the tank and after I did I realised that it can indeed be pulled out of the bottom of the tank and is simply a click-fit. Mid you, it took a couple of hours to get that far!

Anyway, I changed the sensor and ran the engine up, Eureka! no warning light so I put the car back in the garage, pleased with myself for saving on the cost of a mechanic. I had to go to Shoreham today and thought I would give it a run and yes, you guessed - the warning light came on again after a couple of miles. I waited for the engine to cool and checked the reservoir and yes, it was full, so either the new sensor is faulty or there is a different problem. Any suggestions from anyone?

I may try checking out whether the new sensor works, as Allan suggests, but am not sure what to do with the magnet and multimeter.

[aaj]

John

To test the Sender you need to connect the multimeter to the 2 connections & set the meter to read Ohms. It should read as 'open circuit'. place a small magnet at the bottom of the probe (near the black base) and slowly move it upwards towards the tip. at between 3/4 & 2/3 of the way up the meter should change to 0 Ohms. (If you are unsure of the readings , with the meter set to read Ohms & the test leads apart you will get the reading for Open Circuit. When you touch the 2 ends of the test leads together you will make a circuit & the meter will read 0 Ohms).
As my previous post, I suspect that the fault is with the Float inside the Coolant Tank.
AllanJ