Engine/Transmission Oil Cooler

[Isleña]

I installed a Perkins engine/transmission oil cooler using the engine coolant circuit instead of the usual raw water circuit on my Westerbeke 40. No aparent problems till reaching warmer air and water temps in the Sea of Cortez. Now seeing overheating at higher rpms. Temp falls to normal ranges at lower revs. Trying the usual stuff, impellor, belt tension, heat exchanger, hose restrictions, thermostat to no avail. Any thoughts?

[graemek]

engine coolant is to high a temp to act as a coolant,sea water in warm water parts is already border line to high,change it back to sea water cooled will be fine

[RayNWanda]

Yep- Go back to sea water cooling. You also want the oil moving in the opposite direction of the sea water inside the cooler. This improves the efficiency of the cooler quite a bit.