expansion water tank under wing

[fhauser]

XKR 1999.Advice please,the expansion tank under the driver side wheel arch.Should it have some coolant in it or empty when when car not driven,my tank is completely empty.I am not overheating.Also do i put coolant into this underwing tank via the cap on the top of it.
.Thankyou

[M100TWO]

Are you sure this is the Expansion tank and not washer bottle?

[Astromorg]

Yes, that's the atmospheric expansion tank at the rear of the driver's side front wheel arch.

You can conveniently check if it has any content by shining a torch through the apertures near the door hinge.

When I had the wheel arch liner out for some other work I added a vertical, 3 inch strip of green insulating tape with a horizontal line across its middle to mark an arbitrary level. This I use to check if the system overall is maintaining its volume. A bit pedantic, but if the tank's there anyway why not check it can do its job by maintaining a level at least (say) a quarter of a tank?

I add any coolant required with a small/tiny! funnel in the relevant hole in the pressurized expansion tank neck. It's a rare event!

[fhauser]

Thankyou for the reply,but i would like to know do I fill the atmospheric tank from the small cap on the top.The pressurised tank under the bonnet is full but the atmospheric tank under the wing is empty,it is not the washer tank.Thankyou

[Astromorg]

There is no quick way!
I put a quarter tankful in when I had the wheel arch liner out and that is straightforward and I don't recall topping it up in the last year or so. With the wheel arch liner out it would be simple enough to fit a (say) 1/4 inch tube through the filler lid of the tank and out to the door hinge area for future topping up. The only other way in is through the tube from the neck of the pressure expansion tank. There is a very small entry hole, but it's big enough for the very occasional times that a top up is necessary using a syringe type pump and some small dia plastic tubing; or disconnect the hose fitting at the pressure tank - it's not a hose ever under pressure.

[fhauser]

Thankyou Astramorg ,That is the answer i was looking for.Just bought the car a try to double check before jumping in. Thankyou

[mike020150]

It's probably worth saying that the fluid level in the coolant degas bottle under the front wing will vary enormously in normal operation. When the engine's cold, there should be practically nothing in it. When the engine's fully hot, there's insufficient room in the under bonnet coolant expansion tank to take the expanded capacity of coolant in the system so the excess is vented to the degas bottle. As the engine cools, the excess coolant is sucked back into the expansion tank leaving the degas bottle practically empty again. Hence, as long as the under bonnet coolant tank is kept at the correct level, there is no need to access the degas bottle to add coolant. Insufficient room in the degas bottle could prevent the system from operating as intended. Mike.

[fhauser]

Thankyou everyone all ok now