Jaguar xj40 3.2 1986-1994 piston problem and oil pressure problem

XJ40
1

Good morning and congrats for the forum.! I have the model of the topic and when i run over 200klm the piston appeared a hole with marks of electricity as you can see

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. The same problem also appeared to a friend of mine. I changed the piston but we do not know what caused the problem. Does anybody know what could cause this problem in order to avoid happen again?

Furthermore, there is also an other problem. After repairing the engine and when I tried to start the car I had no oil pressure. I connected an external pump, i filled the line and i started again. The pressure i had after that was only one kilo. Does someone have any idea what caused this and how i can solve it?

Thank you in advance.

2

That is classic evidence of severe detonation, brought on by either too lean a mixture, and/or too advanced timing.

The oil pressure may be a stuck-open relief valve.

3

thank you for the answer. I still wonder because it could be the mixture but it is the third time it happens and always on the second cylinder.

4

Low grade petrol can also cause pre- ignition / detonation and could result in a holed piston if the car was driven hard,
Is there a vacuum pipe or any other possible source of an air leak on the manifold in the vicinity of cylinder No. 2 that could be weakening the mixture for that cylinder alone. ?