I just replaced an old Westerbeke with a new/old stock Universal m3-20b. It fires up with no problem, runs smoothly atnd spits what seems to be the appropriate amount of water out of the exhaust, but I was testing it by idling it about 800 rpm and after 20 minutes or so it overheats to 200 degrees and the overheat alarm goes off. It has a new exhaust elbow and new impeller, no signs of corrosion anywhere, and only about 1.2 hours on the hour meter. It is about 20 years old, ordered for a swap but not used. It was stored properly indoors and has fresh coolant. I think I bled the coolant properly-there is an overflow tank and a bleed valve on top of the thermostat, which is at the front high point on the engine. I ran it with the valve open until there was a steady stream of coolant coming out. My original thought was that there was air in the system or a bad thermostat. I tried running it without the tstat and it did the same thing. It seems hotter above the thermostat than on the sides below the head gasket. Any thoughts? The muffler is fairly new as well and I did not see any buildup in the pipe. I had to install a fiberglass reducer from 2 inches to 1 ½ shortly after the exhaust elbow to feed it to the existing muffler. Could it be excessive back pressure from the reducer?
Kevin Burke Mark I 35 Galesville, Md. Sent from Mail for Windows 10
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