Oil or petrol coming through spark plug hole

[steve]

HI got slight problem around number four piston spark plug hole, when the engine is up to temperature and had a good spin down the by pass, i have noticed a slight weeping of oil, or oil contaminated petrol coming out of the plug hole, ive cheched the plug and it is very wet with what looks like petrol, all other plugs are clean, also when checking after a good run, the plug in question is a lot hotter than the rest. the plug is nice and tight in its hole but it still weepes, any advice or ideas would be a great help.


many thanks

steve

[DJT]

First off Steve, is it the same as all the others - i.e. same make and rating? Have you tried swapping plugs around to see if you get the same problem at a different position, or if it still occurs at the same piston? It could be a faulty plug and swapping or substituting will narrow it down.

Dave

[martin]

Hiya Steve, unless something dramatic has happened, you'll find that the oil is leaking downwards onto the plug, probably from the cam cover gasket. I think Dave's right, it's more than likely a duff plug as well, two minor issues, not one. Martin.

[steve]

thanks for the advice, i have swapped the plugs around and the problem is still in the same place,all plugs are not very old, also the oil / petrol is deffinatly being forced out of the plug hole but only when the engine is hot and has been reving, when just ticking over ther is no leak.

[martin]

thanks for the advice, i have swapped the plugs around and the problem is still in the same place,all plugs are not very old, also the oil / petrol is deffinatly being forced out of the plug hole but only when the engine is hot and has been reving, when just ticking over ther is no leak.

It's EXTREMELY unusual for a car to run well and chuck oil out of a plug hole. Crankcase pressure ? are the breather hoses clear ? Has that particular HT lead started failing ?
Try this, remove the offending plug, pull off the king lead from the coil, you don't want the engine to start, and get someone to spin the engine over while you hold a clean cloth over the plug hole, does this leave anything on the cloth, worth a try and it's free. Martin.

[steve]

Martin thanks for that, i will try some more investigation work at the weeekend, but i cant work out how the car is running so well with this oil issue.

many thanks

steve

[martin]

OK mate, do let us know how you get on. Martin.

[jbuckl]

cam cover gasket

[therat04]

HI got slight problem around number four piston spark plug hole, when the engine is up to temperature and had a good spin down the by pass, i have noticed a slight weeping of oil, or oil contaminated petrol coming out of the plug hole, ive cheched the plug and it is very wet with what looks like petrol, all other plugs are clean, also when checking after a good run, the plug in question is a lot hotter than the rest. the plug is nice and tight in its hole but it still weepes, any advice or ideas would be a great help.




many thanks

steve

Steve i do not want to depress you further but is it possible there is a crack in the head across the threads of the plug hole, this would only be hairline but expand under heat of the engine, i have come across this before but not on a stag i hope its not but its worth checking......fingers crossed... Steve