Strutty

3KW is around 4HP, which is, as you say, about 10% of the rated output, but that's measured at 1,200rpm. At 420rpm, it's only about 10HP, so the load was about 40%, which did make it bark a bit!

Many thanks for the input! I've just got back from the boat... spent the whole day messing around with the cooling system. Thermostat checked out fine, so that went back in. Then a mate of mine suggested making sure there wasn't an airlock anywhere (bearing in mind this was a new refill). Well, after a lot of faffing around with various hoses, etc, having let the engine heat for an hour or more, I then gave the engine a few good blasts at higher revs. Before too long, very hot water started making its way round the system, through the skin tank and back, nice and cold. A result! Happy that this problem has been sorted! Now I just need to find out why it's running lumpier than school custard... the whole boat is shaking!

Hi folks I have a 3LW fitted in my boat. It's been sitting idle for 8 months while the boat was built round it. Finally got the fuel supply, starter and coolant system completed yesterday. After some time on tick over, the top rail started to get warm and the temp was around 40C. I applied a bit of load (3KW alternator). The temp then started to rise and was heading past the 70C mark - which I believe is a lot hotter than it should be. My first thought was a sticking thermostat, so I took that out and restarted the engine. I was expecting the return side of the pump to be ice cold (skin tank temp is close to freezing), but it's luke warm, as if the coolant is moving around a bit by convection. The temp did drop away to 30-40C, but I am questioning whether the circulating pump is working properly. I have a gearbox oil cooler fitted in series with the return and that was quite warm too - again, I would expect it to be ice cold with a good flow from the skin tank. Is there any way I can test the pump, without pumping all the coolant out and taking the pump cover off to physically inspect it? Thanks in advance for your help.

I have much the same issue as this with my 3LW. It's been sitting there for about 8 months since last being run in the workshop. I now have the fuel supply, starter, alternator and coolant all sorted, but like the OP here, the engine is running, but it's reluctant to rev smoothly and generally sounds lumpy, as if it's only running properly on two. I've seen other 3LW owners balance a 50p piece on top of the tappet cover. My engine is shaking the entire boat, which can't be right! I'm pretty sure I've managed to bleed the fuel successfully, but is it worth going as far as removing the sprayers to check, bearing in mind my mechanical knowledge is somewhat limited. Exhaust is similar to the OP's - slight white haze, no smell of diesel. I have an Amal lift pump, so will try to check what Martyn suggests. Thanks in advance for any help you can give.

This is partly true. 'Branded' fuels, such as Esso, Shell, BP, Texaco, etc contain additional additives, such as upper cylinder lubricants, cleaning agents, anti-bug additives, etc. One of the reasons supermarket fuel is a bit cheaper, is that they don't contain these additives. Fact. They are added at the point of loading the tanker at the refinery. So it does depend on which white diesel you are referring to. I tend to run my car primarily on supermarket fuel (because it's cheaper), but every 3rd or 4th tankful, will fill up at Shell or Esso. You could achieve the same thing on the boat by putting a shot of diesel Redex in once in a while. This is even more important if you are using the engine on tickover for battery charging for long periods. Also worth being aware that since the introduction of a biofuel element, the brown sludge bug has made its appearance. This cost the retail industry a fortune until they understood what was going on. The bug grows primarily at any fuel/water interface, so it's worth keeping your tanks full in winter, consider an anti-bug additive and/or a fuel polishing system. It is capable of clogging up filters in no time.

And when you've got your head round that, spare a thought for Peukert's Law. If you're running an inverter and pulling high currents, you need to know about this. My honest practical advice would be, if you are using high-drain 230V appliances, such as a microwave or washing machine - run the engine on fast tickover while you're using them. Your batteries and your bank balance will thank you and they will both last longer.