Air in my fuel, Doh!

Submitted: Saturday, Mar 11, 2006 at 21:49
ThreadID: 31658 Views:2000 Replies:5 FollowUps:2
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I've just replaced the factory GQ diesel fuel filter with a Lucas/CAV style. Used one of the machined adaptors off ebay so it fits the existing mount and utilises the factory bleed screw and priming pumps.

however, the little bugger is letting air in, as no end of bubbles keep appearing in the clear bowl.

I can bleed it til they stop, then they come back once the cars been running a while. Car runs fine, cant notice any difference in performance. However smoke seems a little white where its always been black.

Obviously i need to pull it back off and try and tighten it, messy damn job.

Think i like about the factory setup is less bloody seals (read potential leaks)

Has anyone else had this type of problem?



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Reply By: chips59 - Saturday, Mar 11, 2006 at 22:13

Saturday, Mar 11, 2006 at 22:13
i had the same problem but mine was the complete setup, filer and mounting bracket. Did away with the Nissan setup. I traced it back to the screw in fittings where the hose joins on.
AnswerID: 159999

Reply By: Peter 2 - Sunday, Mar 12, 2006 at 07:37

Sunday, Mar 12, 2006 at 07:37
I've had a CAV fitted to every diesel I've owned, usually in front of (upstream) of the original filter. A lot of the smaller vehicles with rotary injection pumps won't handle the additional filter but Cruisers and Patrols do.
Toyota actually fitted a very similar second filter to the later 70 series.
While I've never had any probs with my vehicles I did help a mate who had probs with his and it too was the hose fittings into the top.
If you are using banjo type fittings the copper washers work harden and may not seal when refitted. They must be either replaced or re tempered by heating them to a red colour and allowing to cool.
They are then softer again and will seal when refitted.
This should also be done to vehicles with copper sump plug washers when changing the oil.
I used to always remove the whole CAV filter unit to disassemble on the bench. Replace the O rings when reassembling.
AnswerID: 160021

Follow Up By: MichaelR - Sunday, Mar 12, 2006 at 21:29

Sunday, Mar 12, 2006 at 21:29
Hey Peter2
I have an 80series 1HZ motor and was interested in fitting the CAV type filter. I was interested in your comments regarding fitting the filter in addition to the original filter. By your post I understand this is possible although others suggest that the pump may not handle sucking enough fuel through soo much filter. Are you confident that it will handle the 2 filters and if so how have you mounted the CAV filter in isolation?
FollowupID: 414787

Follow Up By: Peter 2 - Monday, Mar 13, 2006 at 17:33

Monday, Mar 13, 2006 at 17:33
I physically mounted the CAV filter between the Toyota filter and the air cleaner on a HJ and HZJ troopy.
It was plumbed to be the first filter in front of the Tojo one.
On the Humvee it is the only filter.
I have the CAV with the glass bowl on the bottom, if you plumb it as per the arrows on the top the fuel goes through the filter and then into the bowl which sort of defeats the point of the bowl.
A diesel mechanic told me to reverse the flow so that the fuel goes into the bowl and then back through the filter element, that way any crap or water ends up in the bowl rather then in the element.
The 2H and 1HZ will pull through both filters without any worries, use 10mm/3/8" hose so as to not restrict the flow.
Toyota actually fitted a second filter in the same place on later 75 and 78 series.
FollowupID: 414958

Reply By: revhead307 - Sunday, Mar 12, 2006 at 11:21

Sunday, Mar 12, 2006 at 11:21
Thanks Peter and Chips.

I'll have another look at it today, Hadnt considered the hoses.


AnswerID: 160051

Reply By: revhead307 - Sunday, Mar 12, 2006 at 13:06

Sunday, Mar 12, 2006 at 13:06
I fixed it!

After removing it and dismantling, I found the only place the bubbles in the bowl could originate from were two seals at the bottom

one held the glass bowl on itself

and the other was the bottom bleed screw to remove crap and water.

well..a trick for young players (which unlike many on this forum I can count myself among lol) i had overtightened the seal that held the bowl on.

tho it was only hand tight it was putting the o-ring slightly out of skew.

runs like a charm.


AnswerID: 160067

Reply By: Member - Davoe (Widgiemooltha) - Monday, Mar 13, 2006 at 22:25

Monday, Mar 13, 2006 at 22:25
yes but with a lister generator running lucas filter. I ended up fully tightening every furl pipe union I could find . DO NOT overtighten the glass bowl to the filter it WILL crack
AnswerID: 160320

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