Ok... I'm at it again. Whilst motoring in my XJ, ( like that? It's very british is "Whilst" I got it from the owners manual) from time to time, I've noticeda bit of vapor wisping from the front of the car. All hoses, fittings, and the radiator are dry and I can't see any leaks. Thisusualy occurs or is noticable when stopped. It is very slight, and not consistantbut has occured enough to make me take note.I'm curious if anyone else has run across this?

 

Whilst reading through this I assume this to be not too off topic! I shall move it to the proper forum. Is that OK mate? If you dislike it, I can always it return it to the off topic. Just pondered and imagined you'd get better reponses in the XJ forum!

 

Actually.... I did consider that, but it seemed to be a better fit in off topic as it might be more of a generic Jaguar issue than XJ specific. I also figured there would be more exposure in the off topic area as there doesn't seem to be a lot of activity in the XJ40 forum. I suppose on the other hand...it could aslo be a tech question, but six of one, half dozen of another.

 

This is not a Jaguar or an XJ40 problem. You may have a weak radiator cap or a pinhole leak in a hose or component. You may only notice it at rest because the air pushes it away when moving. You may also want to check the fan clutch and make sure it's cooling at rest. If it's beginning to go you may be running higher pressure due to higher temps when the cars not moving and does not have the air to cool it properly.

 

It's very intermittent at this stage, and no indications of an overtemp situation. It has occured when the engine is relatively cool in the early stages of my commute in the mornings and in heavy traffic during stop and goes. No rhyme or reason. We've had extremely hot weather lately with no indications at all, even while in heavy rush hour traffic. Everything looks fine, coolant is clean and levels areok and I can't see any signs a even the smallest leak when the engine is running or after shut down. The electric fans run as normal shutting of a few seconds after engine shut down. I'll just monitor it for now and get the shop to do a pressure test next service check as I'd agree it must lie with the cooling system. Maybe it's just another case of "Jag Gremlins".

 

So... I washed the car the other night and noticed this problem again. The car runs fairly hot in normal conditions and with the large grill openings with that huge rad behind it, the vapor is merely cooler water on the rad surface that is boiling off. No mechanical concerns at all, just residual Jag heat and water splashed on it. I guess that why it was noticable on rainy days or right after a sprinkle when driving on wet roads. DOH. [X(]