I have twin Mercury 250 EFI's Offshore, 1996. Runs in salt water, I am having overheating issues with the starboard engine. I have replaced the water pumps, thermostats and popoff's. Engine runs fine at 2500 RPM but at 3000 RPM will overheat in 10-20 minutes. I have 5-6 lbs water pressure in both engines at 3000 RPM and about 2-3 at idle. Solid pee stream and 5lbs water pressure, even when overheat alarm goes off. If I idle down the engine cools off after a few minutes and alarm goes off. When overheated there is steam coming off of lower unit above waterline. Engine has always been flushed with fresh water, Inside passages seem clean at thermostats and at popoff. I saw in the parts manual that there is a filter screen in the engine but was told that to get to it you have to take off the powerhead.
Should I pull the heads and check the passages? Any other place to get into the cooling system to check and/or flush?
Any help would be greatly appreciated, don't know what to do next.
Also should twin engines be exactly parallel or toed out or in slightly?
Should I pull the heads and check the passages? Any other place to get into the cooling system to check and/or flush?
Any help would be greatly appreciated, don't know what to do next.
Also should twin engines be exactly parallel or toed out or in slightly?