After launch this season I notice the engine only gets to 140 degrees. In the past, if I remember correctly, I would tap on the housing and all would be ok and would much hotter -160 or above. Not so this year. Any more tapping from my hammer and I will break the housing. So I guess I have to finally change the thermostat? It doesn't look like it has ever been changed. Don't think this is a false reading either as my water from the faucets only gets luke warm. Looks like this a easy change right? Two bolts to remove and replace the thermostat and gasket, maybe use some gasket sealant too?
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Pat T, 1995 TR, wing keel, #1388
"Liberty Call"
Burnham Harbor, Chicago
Definitely sounds like a thermostat. My M25XP runs about 170 (below 2000 rpm) and cooks up around 180 when I push her up above 2000-2400. I'd address it first chance you get as diesels need to work and get up to operating temperature to stay healthy.
Should be a straightforward swap, just make sure you burp the air out when you're done and top her up with coolant.
-Dan
Dan & Amanda Reed
1989 Catalina 36 #947 Miss America
Fin Keel Std Rig
FL Panhandle
You might want to try using a heat gun to read the temperature at the thermostat housing. I had the opposite issue, the gauge was reading hot, 210+ and the thermostat housing was really 180. It was a wiring problem to the gauge. Not sure if the sensor could be the issue, but the heat gun would let you know. If you have to change the thermostat, might as well change the sensor. It is probably the original one also.
Bill Deliman
Bill Deliman
Vivacious 2
1989 Catalina 36, Tall Rig, Wing Keel, m25xp
Atlantic Highlands, N.J.