I have twin Perkins turbocharged diesels in my 1981 37' Silverton
cruiser.(T6.3544M). Both engines run at normal temp (180-200 deg F or
80 to 95 deg C) at all speeds but full throttle. When pushed to the
max (2650 RPM) they run up to about 212 deg F or 100 deg C. No steam
from the exhaust and the performance is fine. The system is
freshwater cooled. The raw water impellers have been replaced last
week. All hoses have been replaced and there are no sharp bends.
There is plenty of water coming out of the exhaust at all speed. All
belts have been replaced and tensioned correctly. The 4 thermostats
have been pulled and checked for opening at 185 deg F. The antifreeze
was replaced and dilluted to 50%. There is never any trace of
antifreeze in the bilge. When I drop back to cruise RPM (2000) the
temp drops to the normal range. Even though the engines are over 20
years old there is no corrosion internally and the zincs look fine. I
have a handheld remote thermometer that I can focus on any part of the
engine. I see no hotspots with the exception of the turbos which is
expected. (Air temp can be between 60 to 100 F and water temp between
60 and 85 F) This problem has been getting progressivly worse each
year as this is the first time that it has hit 100C.

The problem (if any) is that at full throttle, the temp gauges are
right at the overheating spot with very little extra to give me any
indication of a problem until it is too late. Any experience with
this problem?

Thanks,

Pete Zimmer
(Jack Daniels Old #7)
Upper Mississippi River Mile 204