Re: Help! Mercruiser 5.7L Engine knock! Marina mechanic baffled!
This is useless WITHOUT PICTURES There was also a "chunk" out of the bottom of the port side head. So, I'm off to get a reman head.
So, I'm back up and running....now that it's time to put the boat away here in Western NY. The head gasket was bad and was causing that horrible knock in my video. Then, we discovered the head was bad. As far as the "chunk" missing from the underside of the head, it was basically a spot that had been eroded away by thermal transfer. It appears the previous owner did a hell of a hack job when previously replacing the head gasket. The head gasket was a different color then the starboard side one, and there was some kind of "goopy sealer" everywhere. It also looked like he tried to use some type of "metal filler" to compensate for the worn metal. What we found was that, since he didn't do it right, there was combustion transfer between two of the cylinders which fired down the metal. So, between those two cylinders, there was an "arch" of sorts. No one around here had a replacement head, so I had to order one from Precision Marine in Racnho Cordero California. (plug plug) They were great to work with, and had reasonable prices. I had both heads milled and all new gaskets installed (of course). Now she doesn't miss a beat and roars like a Lion! Looking forward to next season. Thanks to all for your thoughts and comments. Much appreciated! 8)
