Balbas
Well-Known Member
Its an old Vetus M4.14 33hp. The boat's not been used for 2 years but the engine has been recently serviced. We bought her and put her in the water on Thursday. She was initially very reluctant to start - diagnosed to knackered batteries and finally got it to fire up. And it ran really nicely, no funny noises, or smoke, but perhaps a bit of vibration at low rpm, which felt as though the idle was set a bit low.
Wasn't charging, but got that sorted pretty quickly by Sea Start, so all was then good.
I gave it a workout yesterday - was out in some pretty honking weather, and motor sailing to get into a safe harbour asap. I was giving it the beans frankly. I understand that its rated to 33bhp at 3,600rpm (which seems ludicrously high for a marine diesel to me, but maybe I'm just used to old nails), so I had the revs cranked up to 3,300 (working on the idea that running it at 90% rpm should be ok). An hour or so later the overheating alarm came on. She still had coolant and was still pumping well, so I eased the revs down to 2,200 and a minute or so later the alarm self cancelled. Revs were increased to 2,500 for the next 45 minutes or so into harbour. Yes there's an argument which says I should have shut down the engine the minute the overheat alarm came on, but given the weather I made the decision I would rather keep best speed for as long as possible, so chose to throttle back to see if the temp would drop.
Once in harbour the revs were dropped to idle so that we could check we had forward and reverse gear selection and the motor died and refused to re-start, which I later traced to one of the kids knocking the battery switch to one of the duff batteries (having only replaced the engine battery thus far). I later got her going again on the (good) engine battery.
So where should I begin? I will find out the idle speed and adjust accordingly - that could well cure the very low speed vibration and also perhaps have prevented the motor cutting out when selecting idle revs. Its also possible that the stern gland is too tight - the stuffing box isn't dripping at all, so I guess it's possible that the engine was stopped by a stiff (hot/seizing) stern gland whilst still in gear but at low rpm. Next trip I will take an infra red thermometer with me to measure the stuffing box temperature.
But the overheating at sustained high RPM worries me. Initially, combined with the stopped engine at low rpm and then not re-starting, I suspected HGF, but there is no mayonnaise in the oil, no oil in the coolant and the coolant expansion tank wasn't over pressuring either. And that the coolant alarm re-set when revs were reduced also suggests this is not the case. So where do I start with this? I suppose the following are worth doing:-
Is there anything else I should be looking at?
Wasn't charging, but got that sorted pretty quickly by Sea Start, so all was then good.
I gave it a workout yesterday - was out in some pretty honking weather, and motor sailing to get into a safe harbour asap. I was giving it the beans frankly. I understand that its rated to 33bhp at 3,600rpm (which seems ludicrously high for a marine diesel to me, but maybe I'm just used to old nails), so I had the revs cranked up to 3,300 (working on the idea that running it at 90% rpm should be ok). An hour or so later the overheating alarm came on. She still had coolant and was still pumping well, so I eased the revs down to 2,200 and a minute or so later the alarm self cancelled. Revs were increased to 2,500 for the next 45 minutes or so into harbour. Yes there's an argument which says I should have shut down the engine the minute the overheat alarm came on, but given the weather I made the decision I would rather keep best speed for as long as possible, so chose to throttle back to see if the temp would drop.
Once in harbour the revs were dropped to idle so that we could check we had forward and reverse gear selection and the motor died and refused to re-start, which I later traced to one of the kids knocking the battery switch to one of the duff batteries (having only replaced the engine battery thus far). I later got her going again on the (good) engine battery.
So where should I begin? I will find out the idle speed and adjust accordingly - that could well cure the very low speed vibration and also perhaps have prevented the motor cutting out when selecting idle revs. Its also possible that the stern gland is too tight - the stuffing box isn't dripping at all, so I guess it's possible that the engine was stopped by a stiff (hot/seizing) stern gland whilst still in gear but at low rpm. Next trip I will take an infra red thermometer with me to measure the stuffing box temperature.
But the overheating at sustained high RPM worries me. Initially, combined with the stopped engine at low rpm and then not re-starting, I suspected HGF, but there is no mayonnaise in the oil, no oil in the coolant and the coolant expansion tank wasn't over pressuring either. And that the coolant alarm re-set when revs were reduced also suggests this is not the case. So where do I start with this? I suppose the following are worth doing:-
Dropping the coolant and oil and checking thoroughly for cross contamination
Removing the glow plugs and compression testing the engine
Confirming that the temperature sensor is correctly sited and operating correctly
Is there anything else I should be looking at?
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