Hello , I have a pristine 4 .0 2002 xk8 second owner is myself and I have an issue with the coolant level reservoir depleting ...once a week I put one small bottle 10 oz bottle of water in the reservoir.This has been going on over a year and I have taken the car to numerous shops and every time it’s a problem not solved and a new part and expensive labor bill.I have had the reservoir replaced, the cap replaced, the radiator replaced, the water pump replaced , the water serpentine hose replaced, the fitting plastic fitting behind the block, thermostat housing...and it’s still using a bottle a week...i drive the car about 66 miles a week tops ...and no signs of water on the garage floor., no water in oil, no overheating, just a warning on the dash coolant level low..
Hopefully some here can assit me and advise me what to check...thanks guys

 

Sorry, right block, wrong address.... https://www.jaguarforums.com/forum/xk8-xkr-x100-17/ ...this is the XJ8/XJR residence.

 

You have a coolant leak, with no coolant found on the floor and none in the oil??

When you had these coolant system components replaced, were these one at a time or all at once?

Does the heater work?

 

The water must be going somewhere. Check the heating system. Does the heater blow hot after the car reaches operating temp? Look for leaks under the dash and by the firewall. If your car is not leaking out of external cooling/heating system parts, it must be consuming coolant through the engine itself. It may not be bad enough yet to get into the oil. It may be blowing out through an exhaust port. If so, you're possibly looking at a small head gasket leak. You MAY consider using a head gasket leak sealer. Follow instruction carefully. Often, it will seal up small leaks permanently or at least solve the problem for a several years. You might want to review with other senior members on the forum for their input as well.
https://autoquarterly.com/best-head-gasket-sealers/

 

it’s going someplace out the exhaust pipe? I went through a similar leak for about three months until it got bad enough and Head gasket.then it still did not have water in oil. After it started leaking bad enough I pulled the spark plug on one bank of cylinders. Water was coming out of one of the spark plug holes out of the reservoir on the firewall.

 

it’s going someplace out the exhaust pipe? I went through a similar leak for about three months until it got bad enough and Head gasket.then it still did not have water in oil. After it started leaking bad enough I pulled the spark plug on one bank of cylinders. Water was coming out of one of the spark plug holes out of the reservoir on the firewall.

 

Steam cleaning afect.

 

Excellent example what a relatively small gasket leak can do. If it develops to a bit higher leak, it could cause a hydraulic lock of the piston at cold start, i.e after sitting overnight and enough coolant seeps into the cylinder.

Perhaps a look with a bore scope down the spark plug hole can identify a well washed piston in "Al Gaston"'s engine.

 

So later effects were smoking steam the hydraulic lock over night.mine was a mess.

 

So now maybe it’s time we discussed the elephant in the room. When is a good time to use head gasket sealer? My vote is now in the situation? If it turns out to be the head gasket this might seal it up. If not that was a big job putting on a new one. If I had to go through it again I would use the head gasket sealer and hope for the best. I had always considered the stuff snake oil. But sometimes a little snake oil is a good thing.

 

But, in the meantime, be sure your overflow hoses are correctly attached, Many times, mechanics mis align the hoses.

 

Different time frames by different shops

 

I lose about 3-5 ounces every 500 miles & have had 3 garages pressure test to no avail lol.

 

Thanks... I will try the sealer first

 

So an update on this afternoon I finally got one of them back together that had a bad head gasket I want to do a start and of course I left a pin in the fly wheel oops raised it back up got the pin out and it cranked right up. But it was a temporary situation for this had been off for so long possibly since January I wanted to cycle the oil and then dump it all not knowing what was in it so I just temporary put The valve cover on with two bolts then started it and around the car I had steam coming out the back for five minutes thinking what if I did wrong then all of a sudden it just sealed up or ran out of water whatever it was anyway I got the car up to temperature let it cool down did it again and then dump the oil it looked like iced coffee at least it’s off the car lift. In the next couple days I will finish it up with new gaskets in the valve covers . I guess I’ve just started working on this one. Like I say if I had to do it over again I would’ve dumped the sealer in earlier

 

use k-seal or radweld/subaru coolant conditioner.

bypassing the heater core and flushing it out when you’re done is a good idea