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[redshot]

My 1098cc Clubman has been overheating, i was running it with a thermostat sleeve, but decided to go for a 74deg thermostat. Ive replaced the waterpump with a large impeller type and put a new rad in with still no luck!!!

So looking through these forums I figured i could have a lean fuel mixture which would make it overheat. I've richened the mixture and now it still gets too hot. Plus theres now a knocking noise from the engine!!?

There is a tiny bit of mayonaise under the rocker cover, so could a blown head gasket be causing the knocking and overheating? Or is it possible my timing is out causing overheating and the knocking noise?

Im not sure if it is the head gasket, as theres no oil in the radiator, and the oil on the dipstick looks clean.

The knocking noise does not happen at idle or when revving the engine at stationary, only when the car is moving?

Any suggestions?

[sonikk4]

I would suggest it is the head gasket and the knocking noise could well be one combustion chamber trying to compress its neighbour with the engine under load ie driving. Get a compression test done and this will highlight whether this is the case.

I have had this before on a Vauxhall Cavalier and the head gasket had blown between pots 2 and 3 so one was trying to compress the other on the wrong cycle hence the knocking noise. It sounded really bad when driving but not when idling.