Engine Coolant Low llight on but coolant level fine

I just ran my XJ8 year 2000 4 litre for the first time in a months and have the above light. The coolant level is Ok in the reservoir and in the thermostat housing.

What should I look at ?

Thanks,

Graham

 

Check the float inside the reservoir -- They can stick/ fail. It is a magnet that effects a red switch located outside the tank.

 

The magnet float donut rides on a hollow tube with the micro switch inside. Use something soft, like a plastic spoon to move it. A sticking magnet float is the most common problem with the low coolant issue.

 

Thanks everyone. The plastic knife (and simultaneous try at WD40 to the contact) solved the problem.

Thanks again,

Graham

 

I have the same problem and I for about to use use a plastic anything, so I accidentally pulled the magnet out completely with pliers since its magnet, is that magnetic little thing important? How do I get back in there? Also, is there a fuse for the coolant leveling sensor?

 

If you pulled the magnet out you broke the tube isolating the coolant from the rest of the world . . . and probably the sensor itself. That, I do not think, is repairable.

Fortunately, a new reservoir comes with a new sensor.

No fuse. The sensor is connected directly to the ECU.

 

Hi
A new Coolant Level Sensor retail price is $58.25 (discount price from gaudin jaguar parts.com is $47.70 plus shipping) - part# LNA5740AB.
I also found aftermarket replacement part on Rock Auto Parts website (about $55 plus expensive shipping) - higher price than dealership discount pricing.

Here are some comments from testpoint back in April on the sensor replacement:
"The sensor unit snaps into plastic fingers molded into the bottom of the reservoir securing it to the lip at the top of the plastic housing. Eighty percent chance of breaking the thin rosin tube the glass enclosed contacts are inside if you try to remove it without pulling the tank so you can see what you are doing. Using a screwdriver just pry down between the sensor connector and the bottom of the tank. Doesn't matter if you are replacing the senor as it is isolated from the coolant. Installation is easy as it just snaps in place."


I did a forum search after I resolved this (to try to understand how the coolant level sensor works) and found a posting that Gus posted on the Coolant tank. It is an excellent DIY on the cleaning and testing the tank and the sensor:
Here is the link to his forum posting:
Message: Engine Coolant low - Jaguar Forums - Jaguar Enthusiasts Forum

I liked the pictures and information of this DIY on Gus website so much that I copied it into a Word document and save it as a PDF on my PC . I did this in case I have to refer to it. I may have to print the DIY if I need to clean the tank and the sensor.

Here is the PDF file:
Level Sensor in CoolantTank Stuck DIY .pdf

Thank you Gus for this DIY - Great Photos and instructions

Here is another PDF file I created from the JTIS Jaguar Repair Shop manual - Coolant Expansion Tank Removal/Install:

XJ (X308) Coolant Expansion Tank R&I.pdf

Jim Lombardi

 

Low coolant light had been on my car over 2 years until I changed the coolant reservoir tank.

 

I'm not sure if you can glue it back to the float?

This is a common problem with many cars as they age -- We had this problem with most of the older Ford vehicles in our fleet -- the float was so cheap it surprised us that they worked at all. We never fixed them as the sensor was not available separately and the tank was a $250.00 -- plus we never had any coolant issue with the cars ..ever.

The problem with the X308 Jaguar is that often a drop in the coolant level is the only warning one gets prior to engine death -- so it is very important that it be working. You can't plan on the temperature gauge saving you.

 

thanks for all the info, I luckily had another reservoir that was good, I put the other reservoir in and no more LOW COOLANT, its fixed. Thanks again

 

Awesome thread, I have this same issue as well.

 

Hi guys, I'm sorry to gate crash this post but I'm hoping you can point me in the right direction. I'm new to forums (this is my first ever registration) and I do not have a clue how to start a new post/thread what ever it's called lol. I too am having issues with coolant light and leaking water substance from what looks like it is coming from under the car where the passenger seat is! There is a small leak at the front of the bonnet underneath which is visible on the floor, the other leak is as I described, under the car under the passenger seat location. The water is visible on the floor there too.

I will now await a reply before going into further detail as I do not want to offend by crashing this post.

Again, I apologise but am new to all this and I am unsure of any code to follow when posting.

I'd appreciate any help and advise.

Terry

 

Welcome to the forum Terry,

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Click on the Post New Thread button to get started:



Graham

 

Thanks Graham, will do that now

 

Welcome to the forum. Have you had the A/C running? That could explain the water in the passenger seat area. Could also be some drains are partly plugged and taking a while to empty if it has been raining. Anyway, put your finger in the puddle and see if it smells like antifreeze.
The puddle at the front of the engine is more likely a leak from the water pump or a hose. You will just have to get in or under with a light and search for it.

 

Thanks for the reply Rj237. Yes I have had the air con running and did think of this first. The leak at the front just seems like its water. I'll have a sniff tomorrow when I drive it around lol. Not sure if this is related or not but after putting my foot down or pressing sport button, the car sometimes stalls whilst driving along dual carriageway. It starts up straight away though. It's an XJ8 V8 automatic.

Thanks for reply

 

Funny thing is I've had it fully serviced today and none of this has been mentioned lol

 

Thanks guys for all the information for a long time I have the low coolant light come on and there is plenty of coolant in the expansion tank but if i top it right up to near top it goes away but that top up will go out the overflow but when the coolant light comes on still plenty in tank .The float magnet moves freely and so is it suggested that the probe going into the tank has calcium build up on it. and can i clean this up or get a new one . Glad I am not alone on this problem

 

I am going to be troubleshooting this issue this weekend and want to thank everyone for all the good information.

 

Even though this is an old thread my experience may help a new guy. 98 XJ8. Coolant light on and off intermittently. Checking the tank cool it was full. I followed this thread. Checked connections float,etc. all seemed good. Before I bought a whole new unit I started it with the cap off to see if wiggling the connection made any difference. After a minute or so the tank emptied,sucked into the engine, light came on. So filled it then. Not sure if something else is wrong, we’ll see. But try that first because it’s simple and easy.