Merc 3.0LX Cooling system Question

Vegas Naturist

Petty Officer 3rd Class
Joined
Sep 15, 2011
Messages
81
This happened a couple of years ago, and the engine has been running fine since I fixed it, but reading some of these threads has me concerned. Where is there and where is there not supposed to be water in the exhaust manifold?

Here's what happened. We were running the boat down at Lake Havasu, about 10 miles or so south of the London Bridge Resort where we were staying. Boat was running great. All of a sudden, I had a dead miss, but still had power. I immediately turned around and headed back. When I got back, I checked the motor and #4 was not firing. I pulled the plug and it had moisture on it. Not a lot, but it was damp. At the time, I figured head gasket, so I started pulling the head to take a look. When I took the rocker cover off, I found #4 intake rocker had broken. I replaced the rocker, checked the oil (still clear), and fired it up. Ran great then, and still does. Never had contaminated oil or any other issues.

At the time, I figured that there is water circulating in the exhaust manifold. That the exhaust pressure keeps the water out of the exhaust ports in the head. And since that cylinder had no exhaust pressure, water migrated into the port, and when the exhaust valve opened, water got in and wet the plug. Is this correct (or close)? Or is there something I'm missing here. Other than routine maintenance, the motor has never been messed with, ie. elbows, hoses, etc...

John
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Merc 3.0LX Cooling system Question

I think, since the intake was shut tight, the cylinder would have had negative pressure when the exhaust began to open :eek: and that would draw in some vapor I bet.
 
Top