I have an intermittent overheating problem on my Legend 33 with a Volvo Penta MD 2030. It will run just fine for ever at all speeds but when cutting the engine and sailing for a few hours it overheats shortly after start up and, of course, just when you don’t want it to! The raw cooling water stops flowing out of the exhaust.
I have checked the impellor, looked for blockages at the heat exchanger, all the usual stuff. I did find 4 broken impellor blades blocking the heat exchanger but have now removed them and still have the overheating problem.
I now think that my problem must be an air leak or faulty anti siphon loop valve (if that is what it is!!). The strainer is always empty when I check it and on start up from cold it takes ages for the water to start appearing out of the exhaust. The manual says this should not be more than 30 seconds but it must be more like 3 minutes.
I can temporarily fix the problem by shutting off the inlet sea cock (on top of the sail drive) and then filling the strainer up with bottled water, closing the lid tightly before opening the sea cock again. Water then stays in the system and flows through the exhaust just fine.
None of the pipes seem to be leaking and I have checked the strainer for air tightness.
My strainer is above the waterline and I have what looks like an anti siphon loop. I have checked the loop valve bend and I can blow air into it but cannot suck. It seems to me that this would let air in to the system. Might this be faulty and it should only let air out? Surely then it wont be anti siphon but letting air in can’t help keeping the system primed!
Surely there must be something simple that I am missing!
Any help much appreciated.
I have checked the impellor, looked for blockages at the heat exchanger, all the usual stuff. I did find 4 broken impellor blades blocking the heat exchanger but have now removed them and still have the overheating problem.
I now think that my problem must be an air leak or faulty anti siphon loop valve (if that is what it is!!). The strainer is always empty when I check it and on start up from cold it takes ages for the water to start appearing out of the exhaust. The manual says this should not be more than 30 seconds but it must be more like 3 minutes.
I can temporarily fix the problem by shutting off the inlet sea cock (on top of the sail drive) and then filling the strainer up with bottled water, closing the lid tightly before opening the sea cock again. Water then stays in the system and flows through the exhaust just fine.
None of the pipes seem to be leaking and I have checked the strainer for air tightness.
My strainer is above the waterline and I have what looks like an anti siphon loop. I have checked the loop valve bend and I can blow air into it but cannot suck. It seems to me that this would let air in to the system. Might this be faulty and it should only let air out? Surely then it wont be anti siphon but letting air in can’t help keeping the system primed!
Surely there must be something simple that I am missing!
Any help much appreciated.