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Old 21-01-2015, 19:04   #31
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Re: Drilling into diesel tank while full?

What sort of fuel filter do you have before your engine? Many of them have a 2nd outlet which will prevent a syphoning problem and clean your heater fuel too!

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Old 21-01-2015, 21:04   #32
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Re: Drilling into diesel tank while full?

Install a dip tube at the top, thru the inspection port.

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Old 21-01-2015, 21:57   #33
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Re: Drilling into diesel tank while full?

This is not professional quality advice, but FWIW, our Fab All diesel heater has been running T'd into the main supply line for the engine for ~18 years and over 100K cruising miles. It even works when tapping the rather deep keel tank, with a lift of ~ six feet. We use a small electric pump and 1/4 inch lines throughout. No problems noted with air leaks or inability to lift from the tanks.


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Old 22-01-2015, 10:32   #34
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Drilling into diesel tank while full?

Originally Posted by W3GAC View Post
I've installed several diesel heaters. DO NOT TAP INTO THE MAIN ENGINE FUEL LINE. Three reasons: 1) Air sucks easier than diesel... any breach/ leak in the heater fuel line/ filter line in the future will shut down your engine/ require that you find the air leak, fix it, and bleed the engine fuel line/ system before you'll be able to restart the main. Do you really want to add this unnecessary risk during a storm/ harbor entrance? 2) The typical small piston fuel pumps for diesel heaters are not very strong and can't lift a typical 3/8" fuel line column of diesel very far. Most diesel heater fuel lines are very very small (about the size of a plastic ballpoint pin refill) for that reason and warnings about not tapping/ using regular fuel line are all over the instructions/ warnings. 3). Anytime the main engine is running (especially if your engine has a return line to the tank) it creates a suction on the supple fuel line tap. The weaker heater fuel pump will not only have to overcome the weight of the larger column of the main line but also the negative suction pressure of the main fuel pump pulling fuel up from the tank.

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This may or may not be true. But while ebespacher would prefer to use the standpipe , they do support the fuel line tap. On my boat #4 I did just that, the engine being a 55hp 4 cylinder nanni, both engine and heater never missed a beat

The eberspacher is primarily a truck cabin heater , where they are regularly tapped into the fuel feed.


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Old 22-01-2015, 11:17   #35
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Re: Drilling into diesel tank while full?

Originally Posted by rwidman View Post
What are you going to do about the diesel fuel pouring out once you start drilling until you finish and get the fitting installed?
OK, this is a bit off topic, but some may find it of interest.

I have known mechanics who apply a shop vacuum to the vent port of a diesel fuel tank while changing a valve at the bottom of a tank with a great deal of fuel in the tank. Two things I find amazing are: Air enters the opening at the bottom of the tank with no fuel leaking out with the valve removed, and the air with diesel fumes does not ignite when passing through the vacuum.

And I would add: Don't try this at home! Maybe they used an ignition proof shop vacuum, and know the vacuum power required for the depth of fuel and size of the valve.
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Old 23-01-2015, 19:56   #36
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Re: Drilling into diesel tank while full?

Originally Posted by minaret View Post
Very foolish. We fill tanks with an inert gas (usually Argon) before cutting or welding, even after cleaning. Safety first.

Argon - Wikipedia, the free encyclopedia
Good advice, one thing to remember is an empty or near empty tank is more dangerous than a full tank. I would have no problem though machining on any tank that had diesel in it. Machining and welding are two different things. I don't think either are the solution for this issue.

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