new CAV filter blocked - any ideas why?

[Burnham Bob]

never having changed a CAV filter before i had a go this afternoon. its difficult to get at but managed to secure the bowl and new filter and when the bowl filled up with diesel and the bleed screw bubbled and then ran clear i thought i'd cracked it.

however, changed the engine fuel filter which is a doddle - spin on and easy - tried to bleed the engine filter and got nowhere.

before when i've changed it, gravity has forced the fuel through. a bit of a spit to start with was all i got - i think air ran for a short while and disturbed the remains of the fuel around the bleed screw. waited and waited and then tried the lift pump primer and after a long long time gave up.

before i get back in the locker what could i have done with the CAV fiter that stops the outflow of diesel? that's all it can be - i think!

i've checked again with the bleed screw on the CAV and fuel is definitely getting that far. but doesn't seem to get to the engine.

 

[sailorman]

never having changed a CAV filter before i had a go this afternoon. its difficult to get at but managed to secure the bowl and new filter and when the bowl filled up with diesel and the bleed screw bubbled and then ran clear i thought i'd cracked it.

however, changed the engine fuel filter which is a doddle - spin on and easy - tried to bleed the engine filter and got nowhere.

before when i've changed it, gravity has forced the fuel through. a bit of a spit to start with was all i got - i think air ran for a short while and disturbed the remains of the fuel around the bleed screw. waited and waited and then tried the lift pump primer and after a long long time gave up.

before i get back in the locker what could i have done with the CAV fiter that stops the outflow of diesel? that's all it can be - i think!

i've checked again with the bleed screw on the CAV and fuel is definitely getting that far. but doesn't seem to get to the engine.

did you change the rubber gasket in the CAV head unit

 

[Burnham Bob]

no i didn't - i felt it and it seemed okay so just replaced the O ring down at the base where the glass bowl is.

i have the RYA dvd and they fit a new CAV filter without changing the top o ring......was that where i went wrong?

 

[sailorman]

no i didn't - i felt it and it seemed okay so just replaced the O ring down at the base where the glass bowl is.

i have the RYA dvd and they fit a new CAV filter without changing the top o ring......was that where i went wrong?

you might be sucking air

 

[Fr J Hackett]

you might be sucking air

That would be my guess

 

[Martin_J]

Bob.. I see you are using the lift pump to try and pull the diesel through.. This should be easy and work within a few dozen pumps.

What you didn't mention was whether you had turned the engine slightly to make sure that the lift pump wasn't already on the top of it's stroke anyway...

If you turn the engine over slightly.. perhaps 10 degress at a time.. you will come to a point where the lift pump actually feels like it is pumping.. rather than feeling limp.
Hope this helps. .. FWIW - my lift pump pulled the fuel through both the new primary and new engine mounted secondary filters last weekend with no problems.

 

[sailorman]

Bob.. I see you are using the lift pump to try and pull the diesel through.. This should be easy and work within a few dozen pumps.

What you didn't mention was whether you had turned the engine slightly to make sure that the lift pump wasn't already on the top of it's stroke anyway...

If you turn the engine over slightly.. perhaps 10 degress at a time.. you will come to a point where the lift pump actually feels like it is pumping.. rather than feeling limp.
Hope this helps. .. FWIW - my lift pump pulled the fuel through both the new primary and new engine mounted secondary filters last weekend with no problems.

might depend in gravity fed or like mine where the tank is below the engine

 

[Burnham Bob]

previously gravity fed the fuel through. will check the CAV filter seals tomorrow.

by the way is it pronounced SEE-AY-VEE or KAV?

will also probably invest in a spin-on conversion for the next filter change!

 

[Spyro]

You could crack open the outlet from the cav and see if you're getting diesel out. I suspect you will as there's nothing you could do with the filter that would block it. I would go with the engine not being in the correct position for the lift pump to work.

You haven't still got the fuel shut off at the tank?????

 

[earlybird]

.
by the way is it pronounced SEE-AY-VEE or KAV?

Historically it's C.A.V. (C.A. Vandervell )