I'm on a roll here. 3rd post in one day.

Okay then. I'm losing coolant when I drive our 92 XJS V12. I've had the expansion tank replaced but I still have to top up after each drive. Typically, I'll put in a pint or two of 50/50 mix after I've driven 60 miles so it's not a fast leak. There is no evidence of coolant on the garage floor - oil yes, but no coolant. Well it is a 21 year old Jag after all.

Thank you for any help or advise.

Stephen

 

Disappearing coolant without any noticeable leak anywhere always makes me concerned, because coolant is going somewhere, right? Two things to check. First, are there any oil droplets in the coolant you can see? Depending on the oil weight you use, it might be harder or easier to see. Alternatively, is there any milky white substance in your oil? If so, you just found where your disappearing coolant is going. If either of these is a yes, you may have a bad head gasket. It's probably a small one, though, at least for now.

Another possibility is that you may have a pin-hole leak and your coolant is evaporating. I have doubts about this because you are mixing 50/50 coolant, this doesn't easily evaporate. And, also, the not having any visible leaks.

 

Definitely check your oil but perhaps you just have a little leak that is falling on something hot and burning off? Also check under the front carpets to see if they are wet, might have a leak in a heater hose.

Did you just have the expansion tank replaced? If so they may not have bled the coolant system properly (very common) and you might be expelling air on each drive. Did they drain and flush the system? if so, how much coolant did they put in?

Cheers,

Allan

 

Have you replaced all the many hoses? If not, best to do that. While being done it would be adviseable to remove the radiator (unbolt panel across the top and lift out with the help of a friend), clean it's fins and those of the oil cooler/aircon condenser radiators, and pressure test the rad itself (any rad place can do this). If it does not hold pressure overnight, renew it.

While you have all that out, remove and renew the cross pipe hoses (three). If you want to be 100% sure then also renew the water manifold seals on the front to back pipe.

Presuming no coolant is leaking into the interior from the heater, you should cure the problem, and have peace of mind. There was a recent thread on water manifold seal replacement:
https://www.jaguarforums.com/forum/x...option-102001/

All in all quite a bit of work, but much better than a warped engine if something lets go at the wrong time!

Greg

 

Thanks for the comprehensive reply. Is this something an average guy can handle or should I take it to the pros? Where would I get a set of hoses for my car?

 

Full set of hoses for about $80: www.xksunlimited.com

Not only can you get ALL the hoses you will need, but they also have a pretty neat diagram online of where each hose goes, as your old hoses will probably look nothing like the new hoses due to years of use. In addition, they send you a neat catalog full of diagrams for various parts and nick-knacks for your car, which I admit I enjoy looking through. Kind of reminds me of toy catalogues during Christmas, but for Jag owners!

They are not hard to change. Probably a 4 or 5 on a scale of difficulty out of 10 (10 being highest). However, if you have large hands, the rear heater hoses will be a pregnant female dog as the clamps and hoses are hidden behind the valve covers on the driver's side. You may want to get a friend with smaller hands or rent a child somewhere to help you with those (I joke about renting a child). It took me about three or fours hours to change them out, but I was taking my time. Also, while you're at it, you probably want to at the very least clean the front of your radiator from all the debris that accumulates there. One piece of advice is to soak the new hoses in hot water to make them more flexible, it really does make the job easier.

Ok, I typed a lot more than I meant to. Apologies.