Draining Fuel Water Separator

[dpb]

Just tried googling for a procedure for this and not found anything.
I know how to do the actual draining through the petcock (Delphi type) but should the engine be running or not during the excercise, and do you need to bleed the fuel system afterwards?
Or is it just a case of draining through the petcock and then starting up as normal afterwards.
Thanks.

 

[kashurst]

to drain it through to get out any water or muck that has accumulated the engine must be off. make sure the tank feed valve is open else nothing will come out. Obviously catch whatever comes out in a suitable container. As long as you don't disconnect any other pipes at the same time you wont need to bleed the fuel system.

If you have never changed the fuel filters and/or bled your engine its well worth getting someone to show you how to do it. Once you know its pretty easy. Sooner or later you will need to do it, best to practice at your leisure.

 

[omega2]

Not sure what a Delphi filter looks like but if it's like a CAV unit, and the glass bowl at the bottom is full of sludge, then I would change the filter as well, it is bound to be full of carp.

 

[jimg]

Not sure what a Delphi filter looks like but if it's like a CAV unit, and the glass bowl at the bottom is full of sludge, then I would change the filter as well, it is bound to be full of carp.

Very fishy!!

 

[burgundyben]

Not sure what a Delphi filter looks like but if it's like a CAV unit, and the glass bowl at the bottom is full of sludge, then I would change the filter as well, it is bound to be full of carp.

That's good advice, my CAV filter elements cost less than a pint of beer, I never bother to drain the bowl, if I see any water I slip a sandwich bag up the unit from underneath, undo the top bolt, drop the bag and contents into a bucket, clean up, new element, back together.

 

[dpb]

Thanks for all that, I think what was worrying me was that with the filters on my boat being at the high point of the fuel lines between the tank and engine (normal??) that if I undid the petcock or removed the filters, the contents would syphon back into the tank dragging air into the lines with it hence needing bleeding.
Presumably there is a valve in the filter housing to prevent this maybe??
Understod about changing the filters, I have them at the ready!

 

[burgundyben]

Thanks for all that, I think what was worrying me was that with the filters on my boat being at the high point of the fuel lines between the tank and engine (normal??) that if I undid the petcock or removed the filters, the contents would syphon back into the tank dragging air into the lines with it hence needing bleeding.
Presumably there is a valve in the filter housing to prevent this maybe??
Understod about changing the filters, I have them at the ready!

On mine, I can swap a filter, fire it up at idle and the lift pump pulls it through and bleeds itself before it konks out!

I always carry at least 2 complete spare sets, usually more.

 

[neale]

Thanks for all that, I think what was worrying me was that with the filters on my boat being at the high point of the fuel lines between the tank and engine (normal??) that if I undid the petcock or removed the filters, the contents would syphon back into the tank dragging air into the lines with it hence needing bleeding.
Presumably there is a valve in the filter housing to prevent this maybe??
Understod about changing the filters, I have them at the ready!

My boat is similar. If I undo the drain nothing comes out, but air is sucked in as the fuel drains back. I get around this by shutting off the fuel first which allows me to drain a bit of fuel from the filter to check for carp

 

[Firefly625]

My boat is similar. If I undo the drain nothing comes out, but air is sucked in as the fuel drains back. I get around this by shutting off the fuel first which allows me to drain a bit of fuel from the filter to check for carp

what kind of filters do you guys have... as I couldn't fit a carp in mine...

 

[neale]

what kind of filters do you guys have... as I couldn't fit a carp in mine...

Wot, not even a little one?

 

[dpb]

OK, I have had another look at my filter and as you can see there is definately carp in it !!!.
But at least I now know how to sort it!!!:

 

[omega2]

Do I have to spell it out for you guys?? LOL

 

[SimonA]

That's good advice, my CAV filter elements cost less than a pint of beer, I never bother to drain the bowl, if I see any water I slip a sandwich bag up the unit from underneath, undo the top bolt, drop the bag and contents into a bucket, clean up, new element, back together.

Brilliant advice.

I took mine off and ended up with about half a pint of diesel in my bilge. I'm going to change mine for a screw on filter instead.

The Delphi filters are similar to CAV, they have a CAV style filter with a metal bowl underneath with a drain screw. You can open this to drain off any water/crud. In theory you shouldn't have to bleed the engine afterwards.

 

[burgundyben]

Brilliant advice.

I took mine off and ended up with about half a pint of diesel in my bilge. I'm going to change mine for a screw on filter instead.

The Delphi filters are similar to CAV, they have a CAV style filter with a metal bowl underneath with a drain screw. You can open this to drain off any water/crud. In theory you shouldn't have to bleed the engine afterwards.

Sandwich bags are your friend!

 

[omega2]

If there's CARP in the bowl then filter has it too, change it, they are under a quid, on that site. They come with a new set of rubbers!!

 

[PaulGooch]

If there's CARP in the bowl then filter has it too, change it, they are under a quid, on that site. They come with a new set of rubbers!!

Good advice John, best not to use your rubbers more than once

 

[dpb]

Followed advice and all went well.
Found valves just before the filters so closing these stopped fuel syphoning back but when the petcocks were opened nothing came out. Poked around with a small screw driver with the petcocks removed and quite a bit of water came out before getting deisel, probably about a pint between four filters so well worth doing.
Screwed the petcocks back in and opened the valve and the engine fired up fine.
All the petcocks were very stiff (legacy of lack of service by previous owner) and one snapped off so had to replace one of the bowls.
The plastic bag advice worked a treat.
When replacing the filter and bowl I filled them up with fresh deisel before fitting, this reduced the air in the system and again the engine started without the need for bleeding.
Whilst at it I removed the sender from the tank and sucked some fuel from within a couple of mm of the bottom of the tank with the oil change pump. Happily no sign of water or gunk which surprised me given the age of the boat (20yrs) and that she had been sat with tank half full all winter.

 

[rafiki_]

Good result, well done.