CAV filter

[sailone]

Does anyone know why I am unable to get a good connection to my cav filter using 8mm copper and olives. Is there a adapter to connect 8mm into a cav filter. I am fitting a new Beta with 8mm fuel lines. Has anyone come across this before?

 

[oldharry]

They are made of quite soft alloy, and over-tightening can easily damage the seating where the olive bears on it. It should be possible to reface the seating with a bit of care, though I have never tried it. It has to be pretty well 100% for the olive to seal properly.

 

[uforea]

Not too sure about this but for a CAV filter I would have thought 5/16th pipe and olives, or do you have pipe and olives mixed?

Ted

 

[sailone]

Thanks guys, Ted I think you are right. All my tank and engine pipework is in 8mm. Do you know if is possible to convert a 5/16 housing to take 8mm, maybe a stud. Anyone know the thread in a cav housing ?

 

[pvb]

CAV filters traditionally used a 1/2" UNF thread for the fittings, although new ones are available with metric threads. If yours is a UNF type, you could use a 1/2" UNF to 1/4" BSP union, then connect a 1/4" BSP to 8mm compression coupler to fit your pipe.

 

[sailone]

Thanks pvb yes you are right. Those fittings are avaiable from ASAP I will give them a try.

 

[milfordman]

I think that the CAV filters with the 1/2" UNF threads have an angled seat at the base that is designed to accept a mating angled chamfer combined with the fitting. Where as a pipe and olive expects the pipe to project through the olive. I recently fitted an extra filter in my parafin supply to my taylor cooker and had considerable trouble getting fittings to suit.

 

[boatmike]

Yes that's right and so is pvb. Fit the adaptors with copper washers under the head to seal on the face of the filter. The alternative is an adaptor with a coned end which bottoms on the angled seat at the bottom of the hole which will convert to a parallel male thread which you can then adapt to a compression fitting. most of these are zinc plated steel though and tend to rust so probably plan A is best.

 

[savageseadog]

I thought they were 3/8 BSP or BSPP just to add to the confusion.

 

[MrCramp]

Isn't it easier just to buy a new filter housing with the coorect 8mm threads? Arn't they less than £10 from a commercial vehicle parts distributer? The fewer fittings you have in a diesel line the less likely it is you will get leaks/air ingress.

 

[PCUK]

Although the thread is different, it is near enough that you can carefully screw a 1/4 inch BSP straight fitting into the alloy which will cut a new thread and then use normal compression fitings. Over 25 years and many modified filters I've never had one fail!

 

[davidbains]

I second Mr Cramp. Perhaps it's time for a Racor filter.