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Fuel Tank Drain Mechanism


Paulfc
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As part of my plans to upgrade my fuel hoses I’d like to incorporate a drain tap on the outlet from the tank of my TR6. My current process for draining is to simply remove the hose from the outlet and quickly replace it with a divert hose - but never quickly enough! I’d  appreciate any ideas folk have on how best to easily achieve this in a controlled way and advice on suitable components.

As ever, thanks in advance.

  

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Thanks Pete,

I get the drift of what you are suggesting and will explore options further. I hadn’t considered using standard plumbing components to do it but will explore what’s available.

 

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This may work for you. It did for me on an old Citroen XM. I put an electric pump in line (series) with the mechanical one but at a high point so that it would not leak. It had a non-return valve built in so that the mechanical pump could push fuel through it, or suck it through on the output side. I simply connected it to the battery via a switch after placing a can to catch it. I left it permanently in situ so that I could fill the mower.

I also used it when the mechanical pump became weak until I could sort it.

A 'T' piece and fuel tap would make it a useful permanent 'Feature'.

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The proposal of a tee in the outlet pipe will let you drain the tank or divert fuel for other uses, but if you want to isolate the tank to work on the outlet to pump hoses without draining the tank an in line valve plumbed into the tank outlet fixture would be reqd, the TR6 looks similar to the early Spits ie fuel is drawn from the bottom of the tank with a compression olive and pipe nut locating and sealing a short length of steel/copper pipe which protrudes into the tank to avoid drawing crud off the bottom of the tank.

In the case of the daughters Mk2 Spit I replaced this arrangement with an in line valve with a male screwed end incorporating a compression olive with a short length of copper pipe to extend into the tank was screwed into the tank base female threaded fitting, the tank and its contents can now be isolated permitting the easy replacement of any in line hoses and fuel pump pipework.

I was lucky I had access to a selection of process control valves (all best quality) with all sorts of end fittings, plus in line, right angled and even a 3 way valves, I chose the right angled valve to minimize the length of the arrangement and located the outlet in the direction I wanted. The valve ends had the same olive/pipe nut fitting as the original set up so it screwed directly into the tanks existing fitting compressing the olive onto a short length of pipe, can't remember what the tank base fitting thread was it was 20 years ago and I had access to our organisations substantial Fixed Plant Maintenance  crew and stock.

If I want to drain the tank I simply shut the valve, disconnect the rubber joiner in the outlet piping and connect a length of hose to waste/container and open valve, then have a coffee and wait.

The Vitesse I have also modified to draw fuel from the tank bottom rather than sucking from the top, here I removed the drain plug that goes thro the boot floor and put in similar process control fittings, valve and extended pipe into the tank to the same location of the existing pipe depth, this enables the tank tp be isolated and the delivery pipework to the pump is always charged/drowned so the pump can easily suck via gravity not by syphon through the tank top. 

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Any thoughts about a fuel cut off switch, situated by the tank, that in the event of an under-bonnet fire you could simply switch off ?

And of course an additional anti-theft deterrent

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The proper solution would be a T-piece, with a 'dry-break' connector on the side-T.   Just plug into the side-T and unplug when you have enough drained.

In Rally, cars must have a way to sample fuel, for testing.   This is how they do it.

John

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On 23/09/2021 at 23:55, Peter Truman said:

this enables the tank tp be isolated and the delivery pipework to the pump is always charged/drowned so the pump can easily suck via gravity not by syphon through the tank top. 

I have toyed with that (similar) idea for the 13/60. To my mind the drawback potentially would be 1) any debris will be in the lowest part. 2) all moisture would gravitate to the part (fuel being lighter than water).

In full size marine practice we actually had valves at the lowest tank point specifcally to drain off water from the fuel oil, (settling tanks) the pickup pipes where sited higher.

I suppose, fitting a short length of suction pipe inside the tank, could be a way of mitigating that?.

Pete

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4 hours ago, PeteH said:

I have toyed with that (similar) idea for the 13/60. To my mind the drawback potentially would be 1) any debris will be in the lowest part.

Heralds already have a very handy drain plug - if it's not terminally rusted closed, that is. Free it up, drain out any debris and rinse out the tank occasionally for peace of mind. 

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