"I have a 1986 MCM 170... just
"I have a 1986 MCM 170... just replaced head gasket, intake and exhaust mainfold gaskets and elbow gasket. Replaced spark plug wires, spark plugs, etc. She will start right up but there is excess pressure coming out of the vent in the back of the valve cover. If I remove the oil fill plug, the engine will rev up. The head and valves were clean as a pin. Slight carbon deposits on the top of the pistons. No sign of oil on the top side of the pistons. Is it possible that the exhaust mainfold is leaking back into the head in some way? I really need some expert advice! Thank you in advance for your reply."
"I have a 1986 MCM 170... just replaced head gasket, intake and exhaust mainfold gaskets and elbow gasket. Replaced spark plug wires, spark plugs, etc. She will start right up but there is excess pressure coming out of the vent in the back of the valve cover. If I remove the oil fill plug, the engine will rev up. The head and valves were clean as a pin. Slight carbon deposits on the top of the pistons. No sign of oil on the top side of the pistons. Is it possible that the exhaust mainfold is leaking back into the head in some way? I really need some expert advice! Thank you in advance for your reply."