tigerzetec
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| posted on 1/6/10 at 07:21 PM |
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Fuel Filter Hot on Mercruiser Diesel Engine
Here's a non car question for you.... I have a Motor Cruiser fitted with a Cummins/Mercruiser diesel lump. It is a 120hp Turbo charged unit
with mechanical injection. After a long run with it, i discovered that the 1st fuel filter housing was very hot. Bearing in mind that this is not
fitted onto the engine itself, but is opposite the engine and physicaly screwed to the boat. From the filter, there is an input rubber hose that
connects to the copper fuel pipe from the fuel tank on one side and two rubber hoses on the output side. One goes to a secondry fuel filter which is
on the engine and the other connects to somewhere on the side (possibly from the pump ?) Does anybody think this might be just heat transmitting back
through the hoses from the engine, or could it be something else?
Any ideas greatly appreciated
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daviep
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| posted on 1/6/10 at 08:48 PM |
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Does it have an electric lift pump built in to the filter head?
How hot was the diesel tank?
May just be the temperature of the fuel, remember it does circulate constantly throught the pump and a little bit back from the injectors so it
gradually increases the temp of the fuel tank.
Davie
[Edited on 1/6/10 by daviep]
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tigerzetec
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| posted on 1/6/10 at 09:58 PM |
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Hi Davie, The fuel line on the input was stone cold. Can't easily feel the tank anyway as its encapsulated in a plastic housing and it holds
approx 230 litres of fuel. so it would need a lot of heat to warm that up. Lol. Only the two hoses on the output were hot, and im starting to wonder
if its just the temperature of the fuel as you said thats coming back through on the loop. I just didn't expect the metal housing of it to be
that hot. You can't touch it for long before it starts to really hurt.
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MikeRJ
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| posted on 1/6/10 at 10:18 PM |
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Most likely fuel coming back from the injector leak off.
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Chippy
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| posted on 1/6/10 at 10:56 PM |
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That is because the diesel returning from the engine will be very warm, as it has been through the injector pump, because this tries to compress the
fuel it does get a "bit" hot, :-) Exactly the same on my cruiser, except the return fuel goes back to the tanks. Cheers Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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tigerzetec
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| posted on 2/6/10 at 10:28 PM |
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I Guys, thanks for all your input with this. I have now found out a little bit more. As Chippy says, the return should go back to the fuel tank, but
mine just loops back to the filter housing and then from there, goes straight into the secondry filter which is mounted on the engine. The reason it
has been connected in this way was probably because there was no other easy way of doing it. She used to have a Non injected 4.3L petrol lump which
wouldn't have had a return hose to the fuel tank. Now that it has a modern Diesel lump fitted, but with the original fuel tank, there probably
wasn't an easy way to connect one.
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