Leaking water separator/pre filter

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Posse

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After replacing the filter cartridge in my water separator, it leaks (steady drips) when filled with diesel.

The leak is coming from the seal between the top of the filter cartridge and filter holder.

The old o-ring seal was removed (see attached photo), and the new was installed on the top of the filter cartridge before installation.

I tried re-assembling 4 times, both with old and new o-rings, and with the old and new filter cartridge. Same result.

The water separator is the metal-bottom type, probably Volvo Penta. Engine is a Volvo Penta D2-55.

Any ideas before I replace the entire filter?

20171111_131514_.jpg
 
Please don't use Loctite 577.

Coat all of the seals with clean oil or a thin film of grease. Tighten the top bolt up enough to squeeze the seals, no need to apply gorilla pressure.

Make sure all of the seals are replaced, including the two small o-rings, one on the bolt and one on the spigot that goes through the filter element.
 
PaulRainbow said:
Please don't use Loctite 577.

Coat all of the seals with clean oil or a thin film of grease. Tighten the top bolt up enough to squeeze the seals, no need to apply gorilla pressure.

Make sure all of the seals are replaced, including the two small o-rings, one on the bolt and one on the spigot that goes through the filter element.
Click to expand...

+1

I don't have that type of housing but it looks like a similar fitting to those which used to be found on car oil filters and I would always re-fit those by coating the rubber O-ring with enough grease so that it would stick by itself in the groove in the housing ...... and then offer up the filter cartridge/body rather than installing the ring on top of the cartridge. As Paul says, all spindle O-rings must be greased and changed at the same time so that it seals by just nipping up.

Anything other than a grease or oil is likely to cause grief next time.

Richard
 
PaulRainbow said:
Please don't use Loctite 577.

Coat all of the seals with clean oil or a thin film of grease. Tighten the top bolt up enough to squeeze the seals, no need to apply gorilla pressure.

Make sure all of the seals are replaced, including the two small o-rings, one on the bolt and one on the spigot that goes through the filter element.
Click to expand...
OK so try the grease first, then if this does not work then why not 577 ? The OP is considering a new filter assembly, 577 does not fully harden, so does not render the assembly non reusable, but it will take up minor imperfections and scratches across the seal face. Also the seal recess is outside the element so any excess on the inside falling into the canister would be collected by the filter element.

I would add this is a professional solution from extensive experience with O ring in slot sealing situations. 577 works on oily refrigerant system O rings tested at 20 bar in similar assembly applications (O ring in slot with flat face seal).

Good point about the inner seals.
 
Posse said:
Any ideas before I replace the entire filter?
Click to expand...

There are 2 slightly different sizes of the large seal - one for the top of the filter, one for the bottom. Are you sure you were using the correct one? Your description that "the new was installed on the top of the filter cartridge before installation" suggests you might not have been.
 
superheat6k said:
OK so try the grease first, then if this does not work then why not 577 ? The OP is considering a new filter assembly, 577 does not fully harden, so does not render the assembly non reusable, but it will take up minor imperfections and scratches across the seal face. Also the seal recess is outside the element so any excess on the inside falling into the canister would be collected by the filter element.

I would add this is a professional solution from extensive experience with O ring in slot sealing situations. 577 works on oily refrigerant system O rings tested at 20 bar in similar assembly applications (O ring in slot with flat face seal).

Good point about the inner seals.
Click to expand...

DIY installers often complain that these filters are hard to fit or hard to get a good seal. The usual reason for that is that they fit them dry, without a little lubrication the dry seals stop you tightening the assembly up satisfactorily.

In a pinch, you could use some form of sealant to stop a pitted housing leaking, but as the boat isn't stranded at sea with air in the fuel system i'd rather change the housing if some lube won't fix it.

You obviously have 577 on the shelf, but if the OP doesn't :

https://www.amazon.co.uk/Loctite-K978773-Medium-Strength-Multi-Colour/dp/B002T8WZ8G

New filter head :

https://www.asap-supplies.com/cav-filter-head-3020013
 
pvb said:
There are 2 slightly different sizes of the large seal - one for the top of the filter, one for the bottom. Are you sure you were using the correct one? Your description that "the new was installed on the top of the filter cartridge before installation" suggests you might not have been.
Click to expand...

The seals in my filters are both the same, although i have seen some slightly thicker ones. Certainly doesn't sound like he's fitted all four seals though.
 
PaulRainbow said:
The seals in my filters are both the same, although i have seen some slightly thicker ones. Certainly doesn't sound like he's fitted all four seals though.
Click to expand...

If there's a bowl under the filter, the 2 large sealing rings have different diameters. The larger one sits in the groove in the flter head. The OP's claim that he fitted a new ring on top of the filter cartridge suggests he was using the wrong one. The filter cartridge has a narrow top rim and it would be virtually impossible to get a sealing ring to stay on that during installation.
 
Thanks for all the input.

I am sure all four O-rings are in place. And also quite sure that I matched the correct size of the large ones for the filter cartridge. It fits inside the edge of the top. The slightly larger one fits around the lower part of the filter.

I have lubricated the O-rings with diesel oil, like I always do. Usually does the trick fine.

Someone suggested to me that it may be caused by turning the filter during assembly, causing the O-ring to come out of place, and that may actually explain my problem. At least, I will try to assemble making sure not to turn the filter.

I would rather replace than try to workaround with various sealers, because then the problem will just be there next time, and worst case while at sea troubleshooting.
 
Never used anything to seal these: you do need to have the correct, larger one as stated, and not get a twist in it. If the wrong one is used it will probably roll and twist.
 
pvb, do you mean that the larger one should fit in the top part of the filter, or in the bowl?

I am using the larger one on the bowl, where it seems to fit, and the smaller one in top, where it fits inside the rim of the filter cartridge. Is that wrong?
 
Posse said:
pvb, do you mean that the larger one should fit in the top part of the filter, or in the bowl?

I am using the larger one on the bowl, where it seems to fit, and the smaller one in top, where it fits inside the rim of the filter cartridge. Is that wrong?
Click to expand...

Yes, it's wrong. The larger of the 2 big sealing rings goes in the groove on the underside of the top part of the filter. The smaller one goes on the bowl.
 
Assuming the filters are correct it could be a problem with the edge of the new filter. For all they cost I'd try another. Only time I've had problems with leaks is when the bowl and base weren't lined up centrally.
 
Posse said:
pvb, do you mean that the larger one should fit in the top part of the filter, or in the bowl?

I am using the larger one on the bowl, where it seems to fit, and the smaller one in top, where it fits inside the rim of the filter cartridge. Is that wrong?
Click to expand...

For sure that's the problem.
 
Alright, tried to assemble again today.

I fit one of the larger O-rings in the recess in the filter holder. Seemed to fit fine.

I tried the smaller O-ring in the bowl, and it seemed a bit too small. So I left the old one, which I assume then is also the large size.

Doesn't add up, but on assembly the filter seems to be tight.

Thanks for your help.
 
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