CAV Filters

Submitted: Sunday, Mar 21, 2004 at 14:45
ThreadID: 11430 Views:2164 Replies:4 FollowUps:7
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About to change over to a twin CAV filter system(was given a complete unit) from a standard toyota system(z252).After reading past posts(God bless Truckster and Ozi)about pumps having so called trouble with sucking fuel through these finer filters,has any-one actually had problems fitting CAV filters.Was planning on running filters in both assemblies and changing the first one in line every 5000km and the second one every 10000kms.Also has ony-one ever dropped their glass bowls out in the scrub and busted them.The filter ass. I have has an alloy bowl with a drain on bottom,can pick up a glass bowl for about $20(from memory) but like the idea of alloy(always check for water daily while touring).Thanks all.
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Reply By: Roachie - Sunday, Mar 21, 2004 at 17:20

Sunday, Mar 21, 2004 at 17:20
In my GU 4.2 T/D I use one CAV with a glass bowl, but I carry a spare bowl just in case. If you plan to change @ every 5000klm I don't reckon you'd need a 2nd filter assembly. I have heard of Nissan owners stating that the pump won't pump through 2 filters.
I also use a DeBug unit before the filter to stop any algae or other crud from the tank getting to the filter, thus lengthening the life of the filter. System works well so far.
AnswerID: 51265

Follow Up By: rolande- Sunday, Mar 21, 2004 at 19:38

Sunday, Mar 21, 2004 at 19:38
Whitworth's have CAV filters on special for $58 for a complete unit, did you replace yours with a complete unit or does it mix/match??
Wondering whether it would be worth to save the cost of filters for the current set-up, what do you do with the hand pump on top of the genuine unit, the catalogue one doesn't have a hand pump fitted?
FollowupID: 313007

Follow Up By: Member - Nick (TAS) - Sunday, Mar 21, 2004 at 19:49

Sunday, Mar 21, 2004 at 19:49
Roachie,yeah I didnt reacon I'd need two filters but the unit is one assemblie and I dont want to cut it in half.I could always machine up a sleeve on the lathe to act as a dummy filter if it came down to it.
And rolande,the hand pump hasnt worked on our 4 Runner for a couple of years,all I do is fill the new filter up with diesel and spin it on ,No Worries.
FollowupID: 313011

Follow Up By: Roachie - Sunday, Mar 21, 2004 at 20:17

Sunday, Mar 21, 2004 at 20:17
I got one of those machined conversion adaptors from that well known mob in the southern highlands south of Sydney that we're not allowed to mention on this forum. It simply spins onto the bottom of the standard hand-pump fitting (I think they used lock-tite cos I couldn't get it off when I tried). The CAV fits onto the bottom of that. There is no electrical connection on the bottom (as there is on the original Nissan filter) to warn by idiot light of the presence of water. The only
"problem" (& it's no big deal, really) is that it's difficult to get the old CAV filter off with the pump head in place. So, what I do is remove the 2 hoses and the 2 bolts that hold the assembly on to the bracket and take the whole bloody lot to my work bench where I change the filter in a ice-cream container to minimise the loss of diesel into my engine bay etc.

Nick, I'd give it a go first with the 2 filters both in place and see if there is any obvious drop off in power which might be a sign the pump is having trouble getting the fuel through. If you do have trouble, maybe you could get around it by simply pulling the guts out of a filter to let fuel flow through freely, rather than go to the effort of machining up a blank.

Good luck with it; you'll be pleased with the saving on filters. I usually buy 10 at a time for about $60- all up.


FollowupID: 313019

Follow Up By: rolande- Monday, Mar 22, 2004 at 06:27

Monday, Mar 22, 2004 at 06:27
Thanks for info guys, will be able to look at seriously now
FollowupID: 313051

Reply By: Peter 2 - Sunday, Mar 21, 2004 at 20:53

Sunday, Mar 21, 2004 at 20:53
Give it a go, I was told that a 1HZ in a troopy wouldn't pull fuel through an extra filter when I fitted one back before the Toyota filter in 1992. Never gave a problem since and guess what, Toyota later fitted an additional filter in the same spot a few years later.
What I did was change the CAV filter regularly (5k) and drain the Toyota one at the same time, in ten years I only changed the Toyota one twice as it always got filtered fuel and was never dirty or restricted.
With the CAV plumb them in the reverse direction to the arrows cast into the top housing, then the dirty fuel and water goes into the glass bowl first, most of the crap remains in the bowl rather than in the filter if it is plumbed up the way the arrows indicate.
I always carry a spare glass bowl or two filter elements as an extra filter can replace the bowl. Alternatively buy a shorter centre stem so that only a filter element is required.
With the dual fitting you could buy two short stems, fit the bowl to the first one and a filter to the second, sort of a sideways version of the bowl plus filter.
AnswerID: 51307

Follow Up By: Member - Nick (TAS) - Sunday, Mar 21, 2004 at 21:31

Sunday, Mar 21, 2004 at 21:31
That sounds like a good idea,bowl on one and filter on the other.Anyway now got a couple of options to try,thanks guys.
FollowupID: 313031

Follow Up By: Roachie - Monday, Mar 22, 2004 at 11:32

Monday, Mar 22, 2004 at 11:32
That's a great idea about putting a second filter on if the glass bowl breaks. I'll have to check it out next time I do a filter change......although I'm thinking the filter is about 60mm high whereas the bowl is only around 25mm, so my stem probably isn't going to be long enough.
FollowupID: 313080

Follow Up By: Peter 2 - Monday, Mar 22, 2004 at 17:44

Monday, Mar 22, 2004 at 17:44
Ah forgot about the fact that there are two sized glass bowls, there is the small one like you have and one that is the same height as a filter element. Which of course means there are three different stem lengths as well, filter only, filter plus small bowl, filter plus large bowl or 2nd filter element.
As a matter of interest there are two filter filter elements for a CAV, the normal blue one which is 5 micron and a finer one which is green.
If your vehicle has a mechanical lift pump you can loosen the plastic drain plug while the engine is running and drain any crap out of the bottom of the bowl. Note though that the crap will only be in the bowl if you reverse the hose connections as per my earlier post. If the CAV is plumbed as per the arrows on the top the crap ends up in the filter.
FollowupID: 313151

Reply By: Eric Experience. - Monday, Mar 22, 2004 at 22:16

Monday, Mar 22, 2004 at 22:16
If your dual filter is the long stud one above the other type the filters are in parallel, this reduces the restriction and placing a blank on will negate the filter. It is most important that the filter is plumbed with the arrows in the direction of flow, the way the filter operates is to catch the water and allow it to build up in to big enough drop sizes to overcome the surface tension of the fuel and sink to the bottom,If you reverse the flow this will not happen and water will get into your injectors. It is a major concern to me that so much dangerous misinformation is allowed to stay on this forum for gullable people to read. Eric.
AnswerID: 51494

Reply By: Peter 2 - Wednesday, Mar 24, 2004 at 21:18

Wednesday, Mar 24, 2004 at 21:18
Fo what it is worth a diesel mechanic advised me to run the cav in the reverse direction. If the filter is plumbed as per the arrows the fuel goes through the filter and then into the bowl before going back up to the engine, so all that is ever in the bowl is clean fuel. BUT all the water/crap is trapped in the filter blocking it quicker.
If the fuel is run through the bowl first most of the rubbish ends up in the bottom where it can be seen and the filter element should stay cleaner/less restricted longer. I've been running one this way for about twenty years now with zero problems. Also note that I only use genuine CAV elements as some of the copies leave the centre tube out.
AnswerID: 51846

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