CAV filter leaking

[littledog Biofuels Forum Newbie Find all posts View Profile Close littledog]

Hi Everyone, Has anyone had any problems with a CAV style filter leaking from where the cartridge meets the main housing ass'bly.
This is a new unit out of the box, it was pre-assembled and tightened as far as i am aware as tight as it should be.
I have replaced the fuel filter ass'bly on my hilux 2.8lt with this CAV filter and found that it is leaking from the top seal when the vehicle is turned off, and it is allowing air to suck in when the vehicle runs. The vehicle runs for about 20 - 30 seconds and then dies (even with revving). I have had to change the housings back to the original so that i can run the vehicle but I wish to pursue the CAV filter idea. (the vehicle runs fine with the original housing and filter)

So 1, Can anyone tell me is this a common thing with this style of filter?
2, How tight is tight enough? (this one is tight enough that if you turn the bolt with a spanner, the bottom drain cock turns)
3, is there anything that i can do? I have checked the rubber seals and they look ok (no nicks or anything like that)

Cheers Sam

[Captain Echidna Senior Member Find all posts View Profile Close Captain Echidna]

Re: CAV filter leaking

Perhaps anyone who has managed to succesfully get a CAV to not leak either air or fuel can enlighten us how its done? The only ones I have seen not leaking are on a shelf waiting to be purchased.....

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

Re: CAV filter leaking

A common fault with the CAV is people put the wrong 'O' ring in the wrong places. The 2 that fit above and below the element are NOT the same size and this is the usual place people stuff up.
Apart from that it is always possible the top housing is warped. Being new, I'd be inclined to take it back.

The through bolt can be done up fairly tight. The thread will bottom out so over tightening it should not be possible.

[83Patrol Donating Member Find all posts View Profile Close 83Patrol]

Re: CAV filter leaking

I smear a bit of fuel on the seal before assembling - don't know if it will help in this instance though.

By CAV-style, do you mean a copy - one of those generic no-name housings that's painted light grey?

When I was doing my conversion, that was the first thing I bought, but as soon as I really examined it and saw the cheap looking build quality I returned it. Sales guy tried telling me it was a genuine Delphi - the filter that came with it did have Delphi printed on it (although in very poor print quality so I have my doubts), but the housing was definitely not.

I noticed you're in Vic. Are you in Melbourne? BSP Diesel in Campbellfield sell the genuine Delphi CAV assemblies for only about $15 more than the cheap copies. Seeing as they also give you 2 brass hose tails, it ends up being around the same price.

Maybe give that a try, money permitting?

[littledog Biofuels Forum Newbie Find all posts View Profile Close littledog]

Re: CAV filter leaking

Im not sure if it is a knock off or not, it is an ally housing, but it is not painted. It did come with delphi filter. I didn't assemble the unit, so don't know if it was put together incorrectly. I think that I will be returning it to where i purchased it from.

Thanks for the comments guys and gals.

Sam

[littledog Biofuels Forum Newbie Find all posts View Profile Close littledog]

Re: CAV filter leaking

Ok, So i contacted the supplier of the filter assbly, he said that the bolt that tightens the asslby together may be slightly too long which means that the filter will not tighten properly ( he has seen this before). He suggested to cut 1/4 inch off that bolt to give better tightening ability. He also said that the seals may be no good, but if the bolt shortening doesn't work he will send a known good filter assbly in exchange. I think i will take him up on the offer.

thanks for the comments everyone

Sam

[Fitian Was here Find all posts View Profile Close Fitian]

Re: CAV filter leaking

Who is this supplier?

The bolt does not need to be cut or shortened.

The pipe nut connected to the glass bowl only needs to be adjusted down a little for the bolt thread to go all the way down into it.

O rings should be smeared with oil not fuel.

The wide O ring goes on top of the element and the other goes at the bottom.

The O ring that goes under the bolt head should be also smeared with oil.

After tightening - hold the glass bowl and the filter head and check if they turn. They should not.

[83Patrol Donating Member Find all posts View Profile Close 83Patrol]

Re: CAV filter leaking

O rings should be smeared with oil not fuel.

Oops, that's what I meant - veggie oil being the fuel we're using.

Sorry if I caused confusion, Littledog...

[Fitian Was here Find all posts View Profile Close Fitian]

Re: CAV filter leaking

I knew this is what you meant. I just wanted to make it clear it is oil not diesel or other fuel.

Good on you mate

have a good day

[littledog Biofuels Forum Newbie Find all posts View Profile Close littledog]

Re: CAV filter leaking

I got the unit from Wagga tractors.

I have pulled the unit to pieces and cleaned it. Lubricated the seals with oil and reassembled. The housing and bowl do not move when i try to rotate them.

I am not following the idea about the pipe nut, this unit has a bolt which goes into an ally rod which is threaded on the end. This threaded end goes into the ally drain cock assbly which locates through the bottom of the glass bowl. I cannot see how this bottom part could be adjusted as it is a one piece component except for the plastic drain plug?

I will test it tonight and see how it goes. hopefully the oil on the seals will make the difference. Thanks for the assistance

Sam

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

Re: CAV filter leaking

Do not forget the two larger rubber seals are different sizes, the smaller of the two goes onto the glass bowl, the larger seals at top of filter.

Matt

[Fitian Was here Find all posts View Profile Close Fitian]

Re: CAV filter leaking

I am not following the idea about the pipe nut, this unit has a bolt which goes into an ally rod which is threaded on the end. This threaded end goes into the ally drain cock assbly which locates through the bottom of the glass bowl. I cannot see how this bottom part could be adjusted as it is a one piece component except for the plastic drain plug?

Sam

Sam,

I think what you have got is a copy not an original CAV.

It should work if it is made to specs though.

Good luck

[littledog Biofuels Forum Newbie Find all posts View Profile Close littledog]

Re: CAV filter leaking

Thanks Fitian,
I have sorted the problems (i think). I disassembled and cleaned all parts. Reassembled using oil on the seals, this seemed to make a better seal. vacuum tested the unit and found that all the bolts blocking the other inlet and outlet holes and the bleeder hole on top were all leaking air substantially. Refitted them all with plumbers tape and retested. Vacuum tested ok, no leaks. Fitted to car and bled system through. Started car and drove it. No hiccups or power loss. The old OEM filter must have been pretty blocked (or the OEM housing leaking air as well) because the idle rpm on the car had been dropping off and now is back up to where it should be.

I hope that the CAV filter ass'bly can take some vibration and so forth because I am taking it bush this weekend.

Also dose anyone know how well standard plumbers teflon tape reacts with diesel and biodiesel?

If it fails then it will be back to square one.

Thanks again for everyones help

Sam

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

Re: CAV filter leaking

Also dose anyone know how well standard plumbers teflon tape reacts with diesel and biodiesel?

Thanks again for everyones help

Sam

Sam I am fairly sure that teflon thread take is totally inert to diesel and bio.
It should outlast your vehicle.

[Captain Echidna Senior Member Find all posts View Profile Close Captain Echidna]

Re: CAV filter leaking

The threads on the CAV filter are tapered, if you have a paralell thread (not discussing the same topic in another thread silly) it wont seal as well as a tapered one, however it wasnt my problem.