For those that want to know and see exactly what a coolant tank looks like inside.

I have made a cut away with pictures.

Not a whole lot to it, but the sensor and float inside most have not seen.
Thought I would show you since I just had to replace the entire tank, which comes with new sensor.

About 186.00 plus 50.00 labor to install OEM tank.
Jaguar part # MJD4400BA reservoir-coolant

PS> you can double click on picture to enlarge and read descriptions on the pictures.

Thanks for looking and remember
Happy Motoring...

 

Almost embarrassing to admit this, but yes I did always want to look inside.

I struggled with the float like so many others until I finally bit the bullet and bought a new tank.

 

Awesome. Thanks for sharing and the effort.

 

Thank You for sharing - That is what I love about this forum - you just don't get this anywhere else!

And Mike, I am with you. I changed mine and did not even bother to open it up to see what it looks like inside.

 

Finally pictures that show what I said many times. The float does not indicate low fluid unti the tank is almost empty. Some have said the tank had to be completely full before the light would go out. I tried to dispute that and now maybe they will believe me. Thanks for showing the pictures.

What made you replace the tank in the first place? Had the float lost the magnetic?

 

Good timing, I just did s-tensioners yesterday when I moved the expansion tank 'aside' the probe popped out. I thought I had it back in, just found hole and pushed it in.. ran ok for a day but had a low coolant signal today, though I know I have coolant (realGauge) and it's prop that probe popped back out. I didn't get a good look at the fitting since all the hoses were connected, is there some 'locking' twist or something when inserting it? I check JTIS they indicate to just use a level to remove probe and 'reverse' to install.. well I wouldn't use a lever to put it back in.. any help on this or just seat it up there well, cars hot at the moment, will check later to see what's what and get a mirror out.

 

My old and its new replacement both need to be within 3/4" - 1" of the top or the light will come on. Doesn't seem to make much sense, given its appearance. But, as with many things, they don't make sense until you figure it out and have an 'Aha!' moment.


Me? I've got bigger fish to fry. I don't need to know the answers to everything... :-)

 

This is a little more information on the testing of the float and the sensor. I hope this helps!

Link JagRepair.com - Jaguar Repair Information Resource

 

Well, I had to replace the whole tank because I kept getting "Low Coolant" message. If I took a long screw driver and banged the inside bottom of tank and tried to lift the float, the message would go away for awhile maybe a day or so, but it always came back.

I also replaced the sensor 1 year ago and that worked for that time.

The sensor just clicks into place, you need position the sensor to go straight up and push until you hear the click of the sensor seating itself.
The area where the sensor goes is a sealed area so no coolant is lost, no dripping.
Pretty easy to take out and put back in.
If you develop a "low coolant" message the first thing to do is to remove the sensor from the tank and unclip the sensor from harness and clean the sensor (scrape off scale and then sand with medium to fine sand paper to clean the sensor.
Don't really know how scale gets on sensor since it does not come in contact with any coolant or liquid but it does get dirty, crusty and sometimes a cleaning is all it needs. If you clean sensor and the message keeps coming back then it is most likely a float / magnetic problem which means a new tank.

I am guessing with my old unit the cause was the magnetic part in the float went bad.

Also in the new unit the coolant level is about right in the middle of the tank. 1 ½" to 2" below the top of tank (about half way).
My understanding is if it's any higher and the coolant gets on the hot side it would go to the recovery tank in the front left wheel well until it cools down.

Happy Motoring...

 

Thanks to all who posted about the sensor seating.. I'll be checking it again and probably cleaning it today...

 

Want to give everyone a chance to look inside Jaguar XK8/XKR coolant expansion tank. Not everyday you can look inside.

Happy Motoring...

 

Cannot get the low coolant light to go off . This despite level being full.

Any ideas?i

 

Check your sensor and replace if necessary

 

What might be happening is that the float that the magnet is attached to (or is inside of) has lost its buoyancy and no longer floating (it's become 'waterlogged'). That is why replacing the sensor wouldn't fix the problem.