CAV filters with pumps on top - where do they vent?

[prv]

Apologies for the lack of clarity. I assumed the answer to your question would be implicit in "on my volvo engine I slacken the banjo on the engine lift pump to check the fuel is there". In operating the primer with that banjo slackened when 'solid' fuel started to appear it would have purged any air out through the joint then I could move on to fill the next filter etc.

But you also said

Crack any joint which is convenient after the primer pump if you feel the need but in my view its more about seeing whether anything is happening rather than essential because, as has been said, any air will find its way back to the tank via the fuel return pipe.

which seems to be saying "it is not essential to slacken any joints".

In any case, since I'm building a changeover system, I need to be able to bleed a filter that is not connected to the engine, which means a bleed screw either on the filter head or immediately after it, before the changeover valve. So I'm going to see if LittleShip is correct and the 4-port housings have bleed screws not shown in the photos, if not I will investigate drilling one of the blanking plugs.

Pete

 

[pvb]

So I'm going to see if LittleShip is correct and the 4-port housings have bleed screws not shown in the photos, if not I will investigate drilling one of the blanking plugs.

I've looked at photos of these in Google Images, and there's no sign of a bleed screw.

Thanks. I did consider the add-on pumps, but it seemed a bit daft to get a conversion kit when I was buying new filter heads anyway. It also looked like it would obstruct access to the main bolt and the bleed screw from the front, which is where I need to get at them from.

An add-on pump could be mounted in a number of different ways, to retain access, eg

 

[Deleted member 36384]

Just for interest, a patented automatic bleed system.

http://www.google.com/patents?id=O6EbAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

 

[prv]

I've looked at photos of these in Google Images, and there's no sign of a bleed screw.

That is rather the point of this entire thread.

An add-on pump could be mounted in a number of different ways, to retain access, eg

The right-hand one doesn't retain access, it blocks a spanner from reaching the main bolt from the front, which is the access I need. The left hand image would work, but wouldn't fit in the space I have available. In any case, the filters with built-in pumps are arriving tomorrow

Pete

 

[Heckler]

I've just re-read my initial post to see if I'd accidentally said something different to what I meant to. I don't think I did.

"Open the bleed screw" is not a very helpful answer to a question beginning "there is no bleed screw"

Pete

Pete
I have one I fitted, they just pump to the next thing along, so if its another filter then its the flter, if it is the inj pump then it is that there. Basically crack something down the line. On my MD 22 the circuit is to the pump (bosch VE) which has an internal vane pump which feeds the hi pressure side and then it bypasses to the return to the tank. So in theory, if you wanted to pump and turn the engine, it shold self bleed, but in practice I open the top,of the secondary filter till the bubbles stop and then she will usually start.
Stu