Apparently, when changing the spark plugs on my 93 4.3 OMC Cobra I noticed one cylinder which had not fired in quite some time due to the resistor on spark plug being broken off. Once new plugs were in, I attempted to start motor, upon the first crank of the starter, the motor made a loud backfire and upon inspection the valve gaskets were blown out from under the valve covers on both sides, also the valve covers were deformed after the backfire. My question, what would have caused this much pressure, and secondly how bad is the damage to the engine? Currently the oil level has not changed since the backfire and blowing of the gaskets. The oil is not cloudy or milky, it does not appear to have any water or fuel in the oil.
Would really like to know if just replacing the valve gaskets and covers will be ok or will this just happen again.
Would really like to know if just replacing the valve gaskets and covers will be ok or will this just happen again.