I had my 2000MY XKR at couple different shops over the last year (a jag dealership + a british specialty shop) for various reasons. Each time they always said that the fluid levels were good. Never had a low coolant warning.

I recently learned about the atmospheric tank for coolant (located behind the front wheel arch). I got curious and peered at it from behind the open passenger-side door with a flashlight. It appears to be completely empty when the car's cold. I haven't gotten a chance to look at it fully hot yet, but I turned the car on and watched the tank for several minutes, and didn't see anything that looked like liquid behind the plastic. Am I right to believe that there's no other possible explaination for this other than low coolant?
I checked the coolant level in the expansion tank, and it's a few inches below the top, which is a bit closer to normal but not ideal I think. Rather than believe there was a massive leak in the last few months, I'm trending towards the explaination that these shops didn't bother to check the atmospheric tank, or that they possibly didn't even know about it.

Never touched the coolant before--- I've had the car a year. I know from an old service record that a previous owner (there've been 3) added distilled water in the past, so clearly there was some sort of leak, and I'd assume coolant was added at some point in its life. I'm hesitant to top it off without knowing what product was used. Would it be better to just top it off now or do a flush first? I heard that a flush could be bad for the car.

It looks like the OEM Ford Motorcraft orange coolant was discontinued, and replaced with yellow coolant. They say it's backwards compatible with the orange, and better quality (video link below), but I'm curious if anyone's ever tried it in their XK8. Would love a coolant reccomendation that matches the WSS-M97B44-D spec.

Thanks in advance.

 

The atmospheric tank needs to be at least 50% full for your cooling system to function as designed. Perhaps the fluid in it merely evaporated over the years, or possibly it has a crack in it.

Needs investigation on your part.

heres what use in my 2002 XKR. I don’t have any overheating issues and I drive in the hottest part of the USA. Many long distance trips throughout Oklahoma, New Mexico, and Texas every year.

You would have to contact Prestone to see what standards the coolant meets.


Z

 

+1 on the Prestone Dexcool. Have used it in both of my XK8s past and present.

 

I fill my tank with a large hypodermic thingy through the hose that attaches to the header tank. Remove hose clamp, pull off hose and squirt in the coolant.

Jack

 

All you need to do is fill the black header tank to the bottom of the neck with a 50:50 mixture of OAT coolant and distilled/deionised water or use ready-diluted OAT antifreeze. Check what colour is already in there, probably orange/pink, yellow or clear, and buy the same colour if possible. If you've no idea when the coolant was last changed then you can drain and flush the system a few times with distilled/deionised water and choose whatever colour OAT coolant you wish.

Keep checking the level in the header tank when cold every couple of weeks and, if it's gone down, top it up back to the neck and repeat. Once it stops dropping, you know that you have enough in the atmospheric tank to keep the level in the header tank topped up. If it keeps dropping and never seems to stabilise, you have a leak somewhere.

The alternatives would be to pull aside the wheel-arch liner and half fill the atmospheric expansion tank directly through the top or use a syringe or similar as described above and half-fill it down the tube which connects to the top of the black header tank.

Richard

 

Repeatedly filling the expansion tank is going to be a very slow way to get the atmospheric recovery bottle filled to the necessary level. I don’t see the advantages to this approach.

The difficulty level to properly fill the tank by any of the other aforementioned means is quite minimal.

Z

 

You only need to have sufficient coolant in the atmospheric tank to refill the header tank when the engine cools down. Most of the XK8's I've looked at have a totally empty atmospheric tank so it's not exactly a critical issue.

I reckon that most systems will be filled sufficiently with just one proper filling of the header tank. Certainly, two fillings will be sufficient. Compared to any of the other methods, that doesn't seem like any effort at all. 🙂

Richard

 

When you fill the the atmospheric tank at least half full it cools the coolant that is pushed out of the radiator slowing evaporation. If the tank is empty when it recieves hot coolant it evaporates at a faster rate. Fill it at least half full and forget about it.

Jack

 

There’s a good chance an empty atmospheric tank is empty because it’s cracked .


Z

 

+1 on Dexcool, orange, mine came from O'Reilly's, the autoparts chain.
But you need to be sure it's compatible with what is already in there.
Or else flush and refill.

+1 on filling the atmospheric tank down the overflow from the expansion (header) tank.
You did the right thing to look with a flashlight thru the open passenger door crack (US).
If you have to get to the atmospheric tank, remove the right front wheel and the wheel liner.
Pretty easy but you might need a couple of replacement plastic clips.
Good instructions on this forum.

Have a really good look for leaks and good luck.

 

I've seen a fair number of empty ones but I've never seen a cracked one. It's a fairly robust construction and it's well hidden, which is why most garages have no idea that it exists, but I guess that some might have cracked over the years.
My theory is that garages generally leave an airgap in the top of the header tank of the X100 to allow for heat expansion (as you would do with an X150) and it's that practice which, eventually, drains the atmospheric tank. As I said, it's not a big issue and dozens of X100 are running around with an airgap at the top of the header tank.

Richard

 

motorcraft yellow is prestone. consistently cheaper than dexcool and easy to find concentrate

when the f150s started clogging the new style heater cores a tsb they literally had instructions to drain and refill with prestone

 

Thank you to everybody who chimed in. I picked up some dexcool today and I’ll compare the color to the one in my tank. If they’re identical, I’ll top off both tanks with it. If not, I’ll do a flush first just to be safe.

 

Hi guys, I wanted to post an update with a follow-up question.

I took the car back to the Jaguar dealership to look for leaks and pressure test the cooling system. The shop foreman, who is apparently an XK8 expert, who was there in the 90s doing PDIs (pre-delivery inspections) for the XK8s, says that the atmospheric tank SHOULD always be empty, and that the header tank should be half full. This contradicts ALL the owner recommmendations I've seen here on this website, and the instructional tutorials on youtube.

Where is the official literature that I can reference for a definitive answer on this? If he's wrong, I'd like to provide evidence.

 

100kpa system pressure it vents to the overflow which is pretty much never. car shuts off it sucks back to the expansion tank

overflow is almost always empty

 

Just do what you think is right.


i keep my atmospheric tank 1/2 full, just like every other liquid cooled vehicle I’ve owned or worked on.

i keep the header tank full to the neck.


i put them that way 6 years ago when i bought the car and they have stayed that way on their own ever since.

Z

 

i cant keep mine full to the neck. there is always like 1cm down when i check every month (cold car).

the tank in the wheel arch is half full. not moving.

is that normal?

 

the coolant has to be going somewhere. I suspect a crack in the hose going to the atmospheric tank.

If you don’t add any fluid does the level in the expansion tank keep going down and down ? Or does it stabilize 2 or 3 cm (about one inch) down from the bottom of the neck ?

If it stabilizes, then I’d be happy and move on to other pressing issues, but if it gets lower and lower, then put on your detective hat and start sleuthing.

Z

 

You need to find a new dealer. The Owners Manual for the XK8 says, when cold, "The coolant level should be up to the bottom of the filler neck of the header tank". Simply show the dealer the relevant page in your manual, probably page 21.

The only way that can be achieved is for there to be sufficient coolant in the atmospheric expansion tank to refill the header tank every time the system cools down and draws coolant back into the header tank.

Richard

 

everytime i look it up (and fill to the neck) its at exact the same level. i assume if i dont fill up anymore it wouldnt change at some point.

i have no spots below the car so far.

i think i stop refilling and look what happens or?