swampyankee
Contributing Member
I spent last season debugging cooling issues with the Twin 318s in my "new" 78 Silverton 31. I replaced a leaking heat exchanger on the port engine and all seems fine there now.
The starboard engine has me miffed though. It would run at 160 or so at cruising speeds, but run hot at idle speeds. This caused me to watch temps like a hawk. If I didn't catch it as it crept up it could hit 200 degrees. I cleaned out the heat exchanger and replaced the entire raw water pump. This improved things but the system would still push coolant out into the overflow tank and overflow it. I got to the point of running the overflow line from the tank into an antifreeze jug to catch the overflow.
This spring I've pulled the manifolds and will probably replace them even though they were running cool. While it apart I did a compression check and found pressures between 100 and 125 except for number 8 cylinder, which is 85-90 psi. Granted this is all done cold, after sitting all winter.
My question is, could the head gasket be leaking compression into a coolant gallery and creating the overflow? The engine runs smooth with full power, and doesn't create any steam thru the exhaust or burnt antifreeze smells.
The starboard engine has me miffed though. It would run at 160 or so at cruising speeds, but run hot at idle speeds. This caused me to watch temps like a hawk. If I didn't catch it as it crept up it could hit 200 degrees. I cleaned out the heat exchanger and replaced the entire raw water pump. This improved things but the system would still push coolant out into the overflow tank and overflow it. I got to the point of running the overflow line from the tank into an antifreeze jug to catch the overflow.
This spring I've pulled the manifolds and will probably replace them even though they were running cool. While it apart I did a compression check and found pressures between 100 and 125 except for number 8 cylinder, which is 85-90 psi. Granted this is all done cold, after sitting all winter.
My question is, could the head gasket be leaking compression into a coolant gallery and creating the overflow? The engine runs smooth with full power, and doesn't create any steam thru the exhaust or burnt antifreeze smells.