I have a strange engine
issue. Maybe someone has an idea what the reason is.
One of the two Volvo penta
D1-20 in our catamaran
. To be more precise it always happens when anchoring
typically means going around at idle looking for a place, maneuvering back and forth in idle or around 1000 or 1200rpm with little load, maybe running hard in reverse to set the anchor
. And always in these critical moments the engine
I can cruise
the faulty engine for hours at 2000 or 2500rpm and a few minutes at WOT are no issue but when i'm at the destination
looking for a place to anchor
the engine overheats. The engine also overheats when anchoring after a long sail, the cold engine overheats after 10-15 minutes. Ambient temperature is very high here currently.
What i checked so far...
looks good, output about 11 liters or 2.5 gallons per minute in idle. No steam or smoke from the exhaust
, the water
exiting the exhaust
is warm but not hot.
The impeller is good, the heat exchanger
is clean. The coolant
pump does indeed pump the coolant
. The thermostat works according to spec (starting to open at 90 celsius, fully opened in boiling water). Coolant is new and clean.
I thought about testing the engine without a thermostat but there is a bypass pipe that is closed as the vave opens. If i just remove it the bypass can possibly add to overheatkng so no good test.
Coolant has been drained and refilled a couple of times just in case there are air pockets.
The egine is indeed hot, the coolant is under pressure and steam escapes when the cap is opened.
... What can cause overeating at little or no load but does not cause overheatig at medium to high loads?