Diesel filter/water trap

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sailorbaz

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Bald Knob, Queensland, Australia
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My boat's out of the water at the moment - going back in next Friday. Engine is a Yanmar 1gm10 and there is water in the diesel. Tank has about 20 litres left so I'm going to drain from the bottom and chuck it. The tank feeds from slightly above the bottom to a glass bowl water trap which is below the tank outlet and it's a pita to drain and make sure it's sealed. I'm going to get rid of it and replace with a CAV filter and water trap combined. I would like to mount this on the bulkhead behind the engine but it would be about 10 cm above tank outlet.
Question is: would this be OK? It would be really easy to drain if placed here.
Thanks for any help
Sailorbaz
 
My CAV filter is above the tank outlet and works fine. It is easier to bleed if there is a higher level of fuel in the tank but the lift pump still pulls it through. The secret with CAV filters is to have them easy to get at and when you change them make sure you change all the O ring seals.
 
Should be fine. My filters are a foot or so above the top of the tank, but some boats have their tanks in the keel and the filters several feet higher.

Pete
 
I have the same arrangement with the CAV filter/water separator at least 1.5 meters above the top of my keel tank.

The only think I added to my water separator is a drain tap in the metal base. this makes removing any water in the bottom of the filter much easier. It also allows filter changing cleaner as any diesel in the filter can be drained before unscrewing the filter unit and dropping it into a plastic bag.
 
forelle541 said:
My CAV filter is above the tank outlet and works fine. It is easier to bleed if there is a higher level of fuel in the tank but the lift pump still pulls it through. The secret with CAV filters is to have them easy to get at and when you change them make sure you change all the O ring seals.
Click to expand...

I heartily endorse this. My primary filter is in the shaft tunnel (photos on the website), where maintenance can only be carried out lying down. I have had considerable problems getting the O-rings to seat correctly on the CAV, largely due to the difficulty of accessing them. Since using a spin-on filter on another boat I have now changed to one of them. This does forgo the glass bowl, but as I have never drained water from it in more than 20 years I thought this a small price to pay.
 
My CAV filter is above the tank. I fitted a priming bulb between it and the tank. To bleed the system I only need to crack open the bleed screw on the injector pump; a two minute job. Trying to bleed the system using the priming lever on the lift pump takes forever.
NOTE: Priming bulb has been on three years without any apparent deterioration, but I do carry a spare.
 
Mine is in an awkward place so i fitted 2 studs to the bulkhead. With a wood pad to sit the filter against & longer hoses to the filter.
Then 2 butterfly nuts to the studs - actually they ended up in the bilges so now I use ordinary nuts !!!
Now I can easily remove the filter & hold it over a bucket outside the engine bay where it is dead easy to work on.
particularly handy if the boat is on the water & rocking about.
I can bleed it from this position using bellows & check for leaks before putting it back in place. Any excess fuel goes in the bucket most of the time
( so i can then drop the bucket complete with old filter, rags etc in the saloon for best effect !!!!!!!)
 
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I have something similar in that, when the CAV is on the bulkhead it's slightly above the tank so I can change the filter easily. Once that is done, I just undo the nuts and lower the unit a few inches so it self bleeds. I'm going to fit wing nuts to make it even simpler.
 
I am on the verge of swapping from a bottom feeding gravity tank to a flat bottomed red plastic top suction feed type tank.
How does the water sediment get high enough to make its way into the filter? I haven't had chance to inspect any yet but do the readily available plastic tanks have a collecting 'sump' ?
my old tank had a dimple and drain tap next to the 'take off' tap.
Thanks
 
Daydream believer said:
If you are talking about the filter in the CAV ( now Delphi) unit then the water has already gone through the filter
Click to expand...

I'm not sure I understand you. Surely the bowl of the filter is on the inlet side of the filter so anything collecting there has not gone through the filter. See for instance
Image7.gif
 
I am in dieppe with limited wifi so i hope someone will come along & explain.
The filter you are showing is not the cav water trap pre filter i sssumed that you meant.
The water trap one ( you can google & check) seperates the water in the filter & deposits the water in the bowl after it has gone through the filter.
Please google it & look as i am having a job getting the link loaded. It has been discussed on the forum before
Pvb posted a manual section in 2014 under a thread entitled- how do cav filters work- but i cannot link it with my ipad & i keep loosing the connection.
 
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