Re: Noise from valve cover area, engine lack of power to plane and stall at idle.
I have a OMC 5.7 1987 ish and I recently over heated due to a bad empeller. After I replaced it, I took it out and it ran fine for the first 30 min. then it went to about 25% power and started to knock at full throttle. This is due to the Head gasket going as a result of it over heating. With a bad head gasket you can get water in the engine throught he breach in the gasket. I am only getting a small amount of water in and at idle and very low speed the engine sound and runs great. The reason for the loss of power is due to one or more plugs fouling out. I changes my plugs and this will repeat again once the water gets on the plugs. The inevidable is a head gasket at the least. Once the Head gasket is removed you have to make sure that the heads are not warped/have a wave in them. This can be done with a ridgid straight edge. You have to measure the head in every direction to detect for a warp. If the warping in the head is less that the width of your finger nail, so pretty darn thin, you can get away with not having your heads re-machined. Then all you have to pay for is your head gasket kit. I am a rookie still on the repair of engines; but I am taking classes in the , "School of hard knocks" so these are just my limited experiences and knowledge I recieved form others recently! I am searching for the schematics of my engin now to prepair for the tear down, if you have any good resources for that please share.
