Do CAV filters trap water?

[marki Senior Member Find all posts View Profile Close marki]

Just spoke to a bloke at a 4WD shop who reckons that CAV filters only filter the fuel but they don't act as a water trap. Is this right?
Also, I've seen single and dual bowl setups - which is best for a 80 series 1HZ (1990)?

[W123 x 2 Senior Member Find all posts View Profile Close W123 x 2]

Re: Do CAV filters trap water?

The CAV, Delphi etc. filters do "trap" free water that enters the tank gets sloshed around and ends up in the fuel lines. Most 'trap' filters rely on gravity and allow the free water to settle to the bottom, hence the glass bowl at the bottom (water being heavier than oils/fuel).

What 'traps' don't do well is prevent water that is suspended in solution from entering the IP and on to the engine. To prevent suspended water passing the filter you need an 'aqua block' filter element or similar. This element is treated to repel water allowing fuel to pass (water coalesces on the surface of the element and drops to the bottom) or if a lot of water enters the system all at once the fibres of the filter swell and stop fuel flow altogether - a classic fail safe mechanism.

Racor/parker developed 'aquablock' but the patented coating+fibre combo is licensed to others - not sure to who.

For the record I don't own shares in the company but I do use Racor filters

Cheers, Michael

[Jasper Free from the Majors Find all posts View Profile Close Jasper]

Re: Do CAV filters trap water?

Hi w123x2
So do these aqua block filters fit onto the cav unit or do they have their own head.

Marki.
For the 80 series you can get an adaptor that screws onto your existing filter head and the cav unit fits to that. It is a bit dearer than buying a stand alone cav but you dont need make brackets, re-rout fuel lines etc.
I can't think of why you would need a double unit unless you could put an aquablock type on one and a good plain filter on the other.

Cheers, Chris

[W123 x 2 Senior Member Find all posts View Profile Close W123 x 2]

Re: Do CAV filters trap water?

Hi Chris,
I'm in your neck of the woods and the filters are available from Enzed in Fyshwick (they have a wall display) and The Filter Factory. Most filter places can order them in, I've even seen them on evilbay.

Unfortunately I don't think 'aquablock' cartridges are available for the CAV/delphi type (I'd be using them) and you are obliged to buy a racor housing or head. The racor filters aren't cheap either so I use a CAV 10 micron nominal to take out the bulk of the crud and then a racor 2 micron for the final filter in my TD42 Patrol.

These filters were originally designed for marine applications where moisture in fuel is an ongoing issue. Then adapted for commercial use; large mining equip, trucks and so on. This means their filters are not compact! One or two models for outboard motors are smallish. Helps to have some room in the engine bay.

Cheers, Michael