skipjack27
Petty Officer 3rd Class
- Joined
- Oct 6, 2009
- Messages
- 79
I think this must be a thermostat problem, but would love to hear other opinions:
200hp Volvo AQAD41A driving a duoprop 290 leg, with a problem that has emerged recently. I start the engine and move off at a low cruising speed (usually around 2000rpm or so). The engine begins to overheat immediately and after about 5 minutes or so the overheating is severe, the temp alarm screams, and the gauge shows well over 200 degrees f. I stop the boat and turn off the engine and wait about 10 mins to let it cool off a little. I then restart and the engine runs perfectly normally for the rest of the trip. After stopping somewhere for an hour or two, and then firing up to return home: exactly the same thing happens.
What's going on? How can an engine undergo such very rapid and very severe overheating after initial startup, and then run perfectly normally after a short rest? This has happened on each of my last 3 boat trips. Note that the days have been very hot and the ocean thus quite warm.
I have had extensive maintenance carried out on all elements of the cooling system in recent months, including the installation of a through-hull for raw water intake, instead of through the leg. I can't think of anything that produce a change from drastic overheating to normal operation within the space of a few minutes, other than a thermostat that is slow to open. Irritatingly, the thermostat was one of the many elements of the cooling system replaced not many months ago.
Any ideas? Or experience of this sort of fault?
200hp Volvo AQAD41A driving a duoprop 290 leg, with a problem that has emerged recently. I start the engine and move off at a low cruising speed (usually around 2000rpm or so). The engine begins to overheat immediately and after about 5 minutes or so the overheating is severe, the temp alarm screams, and the gauge shows well over 200 degrees f. I stop the boat and turn off the engine and wait about 10 mins to let it cool off a little. I then restart and the engine runs perfectly normally for the rest of the trip. After stopping somewhere for an hour or two, and then firing up to return home: exactly the same thing happens.
What's going on? How can an engine undergo such very rapid and very severe overheating after initial startup, and then run perfectly normally after a short rest? This has happened on each of my last 3 boat trips. Note that the days have been very hot and the ocean thus quite warm.
I have had extensive maintenance carried out on all elements of the cooling system in recent months, including the installation of a through-hull for raw water intake, instead of through the leg. I can't think of anything that produce a change from drastic overheating to normal operation within the space of a few minutes, other than a thermostat that is slow to open. Irritatingly, the thermostat was one of the many elements of the cooling system replaced not many months ago.
Any ideas? Or experience of this sort of fault?
