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Is the head gasket leaking on my Jaguar XJS?

I have a Jaguar XJS 3.6 Coupe auto. It was laid up for over a year, but fired up and ran smoothly when I bought it eight months ago. I have restored the interior (damp due to leaky screen) but found a lot of water in the plug recess, which I assume must be the coolant. Does this mean the head gasket is leaking or could there be another explanation?

There is a very thin white film in the oil filler tube but the car has sat in an outside garage for eight months being started once a week. There is no oil in the coolant and no loss of either as far as I can tell. It doesn't overheat either. The car had its head gasket replaced less than 3000 miles and three years ago at a garage I trust.

Asked on 8 December 2014 by mickje

Answered by Alan Ross
Well the fits thing to do is to carry out a compression test on the cylinders as that will clarify as to the situation with the head gasket.

Would not have thought that the water in the plug recess is related to it, but for peace of mind, would run the engine to full temp and check for any leaks, ie all hoses/pipes/connections.

If still unsure then carry out a pressure test on the cooling system.
As for the misfire have you actually checked the condition of the plugs( or switch number 2 plug with another and see if the misfire stays or goes with the plug.)
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