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fuel valves

Posted: Jun 24th, '14, 04:38
by Todd Pearce
Looks like I need to replace the fuel valves in my B42,1986, the two engine valve switches may be a bit old and tired and I was hoping to make life easy by replacing them like for like, they look simple enough but they control the fuel supply and I think the return flow all in one , on the top plate it is simply marked ,forward, aft off, so no biggie ,but some times we struggle to get the right threats down here as we are metric based not imperial, so if anyone knows what they are and where to get them , I`d love to know
Cheers Todd

Re: fuel valves

Posted: Jun 24th, '14, 08:10
by Navatech
On my B46 these fuel selector valves operate both the fuel source and the fuel return... You don't have to have the return flow to the same tank but if you don't, one of two things might happen:

1) That tank will run out of fuel a lot faster then you're used to... The missing fuel won't be gone though, it will be in the there tank... Which leads to the following:

2) You might actually cause the other tank to overflow... If you don't catch that in time you will be pumping fuel overboard...

Don't forget, a diesel will have it's lift pump supply anywhere between 30% - 100% over it's actual consumption... This fuel will serve to cool & lubricate the injection pump and, if you have combined injection pump & injectors (like on the Detroit Diesels) it will cool & lubricate those...

IOW, you could jury-rig two valves (one for the supply and one for the return) instead of the dual valve but sooner or later somebody is going to make a mistake...

What you're looking for is something like this:

Image

http://www.amazon.com/Groco-FV65038-Por ... ctor+valve

http://www.enginegearonline.com/6-port-ball-valve/

http://www.downwindmarine.com/Groco-Fue ... 02033.html

http://www.andersonbrass.com/multi_port ... valves.php

http://www.andersonbrass.com/SELECTOR_VALVES.PHP

Getting these with metric threads is going to be a bear... I think you'd be better off getting a machine shop to do you you a set of thread adaptors instead...