Following Along – Diagnosing a Head Gasket Issue on the 1971 Jaguar XJ6

As with any classic car, you want to try and exercise a certain amount of reserve and caution when working on them. Try to be sympathetic to their age and their condition. So, when the 1971 Jaguar XJ6 that we have had in at Bridge Classic Cars developed a misfire our in-house restoration team did everything they could before having to dive deep.

The XJ6 has had its fuel tanks replaced, new fuel lines and was tested by our technicians. Before the tanks were replaced this classic Jaguar had real trouble staying running. Now though, it will run for as long as there is fuel in it. However, now that it was running long enough, Dave noticed a misfire on the big straight-six.

Originally Dave thought it to be connected to the ignition system. It would arc out to the nearest metal point. We also discovered exposed wires in the connectors that join the condenser. Those were all then replaced along with the HT leads but to no avail. It had got marginally better but the misfire was still rather prominent.

With that, our in-house engine guru Ady was called in to take a look at the straight-six. The only thing left to do was to gently remove the cylinder head. Carefully and patiently, Ady eased the head from the block to expose the pistons but more importantly the head gasket. On the cylinder closest to the firewall, the gasket was in tatters. The XJ6 had blown a head gasket. Also, Ady had noticed coolant marks down the side of the block. Another sign that the gasket is not sitting correctly between the cylinder head and the engine block.

With that, it also damaged the chamber of the corresponding cylinder in the head. A large chunk of material is missing from between the leading edges of the valve. But, all may not be lost. The head is currently in the process of being stripped down and assessed so that a plan can be made to get this wonderful straight-six back in action.

Once the plan for the XJ6 engine has been confirmed, work will begin to get the car back to its former glory.

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