Engine fuel line engineering problem

[Polishicebreaker]

Hi Folks, I have a little problem which I’d be very grateful for some assistance with. 
My current fuel line installation is a gate valve welded on the side of the fuel tank which then has a reducer to 5/16 fuel line. 
unfortunately the gate valve has seized open. 
I’ve removed pipe and put a temporary bung in there.  What is the best way to fit new isolation valve? Am I right in thinking if I use a 5/16 valve my fuel pipe will go directly on one end but I’ll need a female to female coupler to get to the existing reducer from the redundant gate valve or is there a much easier way to do this?

 

many thanks 
 

[WotEver]

7 minutes ago, Polishicebreaker said:

My current fuel line installation is a gate valve welded on the side of the fuel tank...

Are you sure?  Could it be a gate vale screwed onto a stub which is welded onto the fuel tank?

[Polishicebreaker]

Erm , I didn’t think so but maybe worth another look 

[Tracy D'arth]

You cannot weld a brass valve to a steel tank.

How about a small piece of 5/16" pipe into the existing reducer in the valve and then a new 5/16 " valve between that pipe and the flexy?

Edited June 17, 2020 by Tracy D'arth

[Polishicebreaker]

It’s not too far off the uxter plate though so would there have been enough room to thread it on? 

Good point!! 
 

I’ll take another look 

[WotEver]

1 minute ago, Polishicebreaker said:

It’s not too far off the uxter plate though so would there have been enough room to thread it on? 

Only you can answer that.

[Polishicebreaker]

It's only around 25mm clearance

[Jen-in-Wellies]

Can you post a photo of the gate valve to tank connection? Might help with working out how it was attached.

Jen

[Polishicebreaker]

Sorry this is a rubbish pic 

I’ll take another when I’m back in around 15mins 

[Polishicebreaker]

[WotEver]

Any chance of getting in there with a wire brush and cleaning all the crud off?  Good pictures, but it's really difficult to see what's what.

[Tony Brooks]

Try a pair of gland nut pliers on the wheel. Those things do tend to jamb.

 

I suspect it you drained the tank and unscrewed the gubbings from the valve you could twist it and unscrew it but as draining is not exactly easy I think Tracy's idea is the way to go.

[Tracy D'arth]

I would suspect that the operating part will have to be unscrewed from the body to allow the body to be unscrewed from the tank.

That is going to be difficult, the tank will have to be totally drained first.

The way out is to put a new valve in the pipe as I have said.

When you say its jammed, nothing to lose, try harder to turn it clockwise.

[Polishicebreaker]

The wheel turns ok and feels like it’s closed but doesn’t do anything. 
 

There’s definitely no space to turn the fitting. 

I like your idea re small length of pipe to a new fitting. 
my feeling is to leave the valve alone as it’s not going anywhere. 

[crossley]

What's on the other side of the bulkhead to the valve? 

Under the aft deck plate? Please don't tell me the valve is screwed onto a stub welded in the bottom of the tank.

Looks like a 1/2" bsp F Female valve screwed on to a nipple welded into tank wall.

They must have dismantled the valve to fit it in the first place.

Have to drain the tank first

 

[Polishicebreaker]

No access to inside of a fuel tank. 
 

[crossley]

Does fuel come out when plug is removed?

[WotEver]

Just now, crossley said:

Does fuel come out when plug is removed?

Yes, that's why he fitted the plug.  Explained in the OP.

[Tracy D'arth]

If its jammed open the spindle must be broken above the thread that screws the gate wedge into the body, unusual. Generally they jam closed and the spindle snaps when you try to open them.

How many turns have you given it?

 

[WotEver]

7 minutes ago, Polishicebreaker said:

I like your idea re small length of pipe to a new fitting. 
my feeling is to leave the valve alone as it’s not going anywhere. 

I agree.  Leave replacing it for a more convenient time. I agree with the others that if you dismantled it then it would probably unscrew, but no point right now.

[crossley]

He's going to have to drain the tank then or risk it snapping off. 

[Tony Brooks]

2 minutes ago, WotEver said:

Yes, that's why he fitted the plug.  Explained in the OP.

He even sent  a photo!

[WotEver]

Just now, Tracy D'arth said:

If its jammed open the spindle must be broken above the thread that screws the gate wedge into the body, unusual.

Wouldn't the handle then just lift off together with the sheared spindle?

[Polishicebreaker]

2 minutes ago, Tracy D'arth said:

If its jammed open the spindle must be broken above the thread that screws the gate wedge into the body, unusual. Generally they jam closed and the spindle snaps when you try to open them.

How many turns have you given it?

 

Maybe a couple of turns but it definitely won’t go any further 

[Polishicebreaker]

Which brings me to the question..,, 

 

can I use 8mm pipe, not sure that my chandlers will have 5/16?