CAV filter issue

zebek

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I tried to change my filter, and have struggled with the seals in the past, as can never quite get a seal the right size for the top of the glass bowl, and keep re-using the old one, any ideas?
Anyway, not my main issue today, got it all put togther, and tried to refill, but after a short while the fuel started coming out the breather screw before fuel had got to the the glass bowl, whats the likely cause (got me stumped)?
Some additional info, on the removed old filter i did see some sludge suspect bug, see pic. And old filter has no holes on top surface, but new does, again see pics - any pointers here to my issue above?
 

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vyv_cox

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Wrong filter?
I can never understand why folk have problems changing a 296 type filter cartridge. I have fitted thousands without any problem.
Make sure that all the old rings are removed, lightly grease the top ring if it helps to hold it in. Get everything square on before tightening.
Access to mine is far from ideal but it's the angled seat between the glass and the filter canister that creates the difficulty. Not a great design, makes far more sense to replace with something better.
 

srm

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Likewise, after a few years of fiddling with CAV filters I changed to spin on fittings, so much easier, especially if you have to change a filter while out at sea.
 

snowbird30ds

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I have never changed one at sea, how is it different please?
An easy task is completely different when bobbing around while trying to look anywhere other than the horizon, get a lively sea and a simple job can be near impossible especially with bad access.
I switched my pair of CAV filters down below the deck behind engines for racor copys mounted nicely accessible from the saloon under a seat base, so much easier and a quick top up from a bottle of fuel means no bleeding needed.
 

penberth3

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I tried to change my filter, and have struggled with the seals in the past, as can never quite get a seal the right size for the top of the glass bowl, and keep re-using the old one, any ideas?.......

Don't you get a set of new seals supplied with the filters? They always were, perhaps I'm out of date.
 

wrr

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While I have frequently replaced CAV filters and seals at rest, the thought of diesel bug and having to replace the filter during a passage in difficult sea conditions was enough to persuade me to fit the ASAP adaptor and Racor filters. Combined with a filter wrench and a appropriately sized mixing pot to catch any diesel, this arrangement makes a filter change far less daunting.
 

PetiteFleur

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I also had problems with the CAV filter - discovered that there were TWO filters in the upper seals. Only found when I removed the filter and reassembled at home. I've since replaced it with the spin on type, if you do this make sure you get the correct threads for the inlet & outlet. Originally was UNF but modern ones are Metric thread.
 

Roberto

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is that the correct filter, I thought they had holes in the top and slits in the bottom?
There are various types, Perkins part for example fits in a CAV head and has the top side like this. Likewise, Fleetguard replacement is FF167, the FF167 has no slits on the bottom face, whereas the FF167A (like Agglomerator) has slits which should hopefully give a rotational movement to fuel and help coalescence.

filtre-a-gasoil-perkins--15496.jpg
 

penberth3

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I also had problems with the CAV filter - discovered that there were TWO filters in the upper seals. Only found when I removed the filter and reassembled at home. I've since replaced it with the spin on type, if you do this make sure you get the correct threads for the inlet & outlet. Originally was UNF but modern ones are Metric thread.

Eh? Do you mean two seals in the upper filter? Square section outer seal and an O-ring on the spigot?
 

Stemar

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I sacked the one on my Snapdragon 24 after it blocked as we approached the entrance to Portsmouth Harbour, resulting in a rather fraught entry under sail in F6/7. I went to the local car breakers and got a pair of spin-on filter holders. A bit of pipe and a few taps form ASAP and I had a pair of filters. The whole thing cost about £50, I suppose you could double that today. Looking at the price of Snowbird's suggestion, I wouldn't even bother going to the breakers now.

If one blocked, I could switch in seconds and I reckon I could have swapped the dead filter with the engine running, though I never had to try. Of course, with such a good setup to deal with a blockage, I never had any more problems, so I ended up only changing filters when they got uncomfortably rusty, after about 5-6 years.
 
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