Finally tracked down latest coolant leak to fitting holding temp sensor..was only leaking,I guess, when running hot and evaporated on the block, however with the cold weather here I noticed a tear drop on the pipe Assy, I thought it was cracked but on close inspection the fitting was wet, car is garaged but I think low temp contracted the metal fitting and allowed it to leak without any pressure.
Needless to say I have a new assembly with thermostat, I should run to operating temp with the expansion tank open to bleed??
Hope this is the last leak for a while, glad I caught this as sensor was quit loose and would have been a mess if blew out on the highway.
Jeremy

 

The system is not that hard for bleeding off air. Top off the expansion tank and warm the engine to operating temp. The turnthe Climate control to HIGH heat. This will manually open the heater circuit. Once you have heat set the temp control to your normal temp. Shut it down and let it sit to cool and then check the expansion tank level and top off as needed. If during the high heat the low temp comes on shut it down and let it cool and top off.
The system is a low volume/high velocity and will generally self bleed. The only sticking point is the heater core.

 

The trick I use is this: during the initial fill up, I aggressively "pump" the water by squeezing/releasing the radiator hose. This usually pushes most bubbles out, so at least you are not starting near empty. As pointed out above, the system will need topping off a few times before settling on empty.

Best of luck.

 

As suggested above, be sure to check the coolant level in the expansion tank each morning for at least four or five days afterwards. I have found that anytime I have to replace any cooling system parts (most recently a new expansion tank back in September), it takes a few days for all of the introduced air to bleed out of the system, so I must gradually top off the coolant each morning until it finally remains at the proper level just below the cap....

 

Me too.

The design of the thermosat housing on the N/A engines goes back to the introductory model year when the recommended refill procedure was to unscrew the cap and fill through the housing.

This technique and the fitting of the second bleed hose from the Expansion Tank to the Radiator were soon discontininued when it was found they made no difference to air bleeding.

Graham

 

Thanks for all the info installed new pipe and thermostat and refilled system, ran to temp(198-202) after cool down needed about 1/2pint will monitor for next few rides
Thanks again
Jeremy

 

Jeremy,

That's a lot of additional coolant.

Could be more than just a bleeding issue. Worth checking the connection to the Atmospheric Recovery Bottle behind the RH wheelarch liner to make sure it's pulling coolant back and not air as it cools down.

Graham

 

I just changed the coolant on mine - 5 litres or so for the initial re-fill, then topped it up again a couple of times. 1/2 a US pint (rather than 1 or 2 pints) is less than 250ml, which is probably less than what I topped it up with - that didn't seem excessive to me?

 

Thanks Graham, will keep that in mind don't expect to run her again till next weekend, weather being what it is, will report outcome.
Jeremy

 

I have had my XK8 for just 2 weeks and have been checking the coolant level regularly.
I top up to the top of the expansion tank, but when I check it next time, it it's always 30-40 mm below the top.
Is it suppose to be at the top of the tank all the time?
I haven't checked the recovery tank that GGG mentioned as I didn't know it existed.
I assumed that overflow went to ground.

So if the recovery tank is working, [haven't checked yet] should the level in tank be at the top all the time?

 

ORIGINALLY posted BY FMERTZ

"Besides the black tank near the strut tower on the driver side (where the cap is), there is an overflow tank in the driver side front wheel well. It can be seen/reached by removing the plastic liner. My understanding is that this wheel well tank is not under pressure. It captures whatever goes past the cap when hot, and provides a ready made supply when the cooling system sucks the fluid back in during cool down. I assume that the normal operation of this tank could technically produce a smell, even if there are no leaks. Are you in need of refilling the system on a regular basis?

As you found out, there are a number of "usual suspects" for coolant leaks. You could add the radiator end tanks and the water pump to the list.

Separately, if you start meddling with this, you might want to look into the whole thermostat tower, including the upgraded aluminum model. Fairly easy DIY, and parts are not that expensive."

Hope you find this helpful, I know I did
Jeremy

 

EXACTLY. It's the Atmospheric Recovery Bottle and as this awkward name at least confirms, it's not under pressure.



The level in the Expansion Tank should always be at the bottom of the filler neck when cold. The Atmospheric Recovery Bottle can be anywhere between an inch to half full. There is no right or wrong level for the contents.

Graham