capnsensible
Well-known member
Top tip. :encouragement:
CAV filter not sealing
- Thread starter Kelpie
- Start date
Top tip. :encouragement:
Cockaigne
New member
Stemar
Well-known member
Now imagine having to change one in the dark, on a lee shore, with the boat leaping up and down in a 6ft swell and the crew screaming that the rocks are getting closer. That's why I gave mine its P45
Having twin filters, that are so easy to switch means I don't change them every year - in fact, I changed them both last year, for the first time in 10 years, but only because they were sufficiently rusty that I was starting to be concerned about pinholes. I've never needed to, but I'm pretty sure I could change one with the engine running. It'd probably be messy, but on that lee shore I can live with a bit of mess!
Sandy
Well-known member
I changed from a CAV to a top loading filter last winter. Another issue engineered out to make my sailing more pleasurable.
penberth3
Well-known member
I always found it easier to start by pushing the ring into the groove at four opposite points (north south east west if you like) then push down the bits in between. Otherwise you can be chasing it round and round as it keep popping out of the groove.
penberth3
Well-known member
No particular reason, but I wouldn't introduce silicone to a fuel system. What's wrong with using a spot of ordinary mineral oil or grease if you want to lubricate the seal?
omega2
Active member
RichardS
N/A
Spirit (of Glenans)
Well-known member
Yes, I thought engine oil was the standard recommendation.
PaulRainbow
Well-known member
A film of diesel is all that's required, which will be to hand (more likely on your hands 
) and is guaranteed not to cause any issues if it gets into the fuel system
As for the Sea Start video, IMO it was a bad idea for them to skip changing the top seal. Fair enough if you were doing one at sea, but as a routine maintenance filter change, i change all of the seals, every time.
) and is guaranteed not to cause any issues if it gets into the fuel system As for the Sea Start video, IMO it was a bad idea for them to skip changing the top seal. Fair enough if you were doing one at sea, but as a routine maintenance filter change, i change all of the seals, every time.
omega2
Active member
Make you right, I change all FOUR, yes Four, top and bottom, plus the "o" ring on the spigot and the one on the through bolt.
Kelpie
Well-known member
Just to update, I found time today to look at this. The filter I'd been trying to seal had actually crushed out of shape in my more and more desperate attempts to get a seal- they are pretty flimsy little things really.
The mistake I'd been making was to put the seal on the bottom of the filter and then offer up the bowl- it works much better the other way around!
Have also followed advice to use the bigger seal on the top, smaller on the bottom. Did a few hours of motoring today, not a drop of diesel leaking, and no problems starting or idling. In fact I can even start the engine in idle now quite readily.
So a good result and a big improvement to our peace of mind- thanks everyone
The mistake I'd been making was to put the seal on the bottom of the filter and then offer up the bowl- it works much better the other way around!
Have also followed advice to use the bigger seal on the top, smaller on the bottom. Did a few hours of motoring today, not a drop of diesel leaking, and no problems starting or idling. In fact I can even start the engine in idle now quite readily.
So a good result and a big improvement to our peace of mind- thanks everyone
pvb
Well-known member
Also see post 26....
ip485
Well-known member
I always thought this was one of the uses of vaseline - having just the right consistency.
Hadenough
Well-known member
Whenever I need to change the element on a CAV I always replace the whole thing with a Racor 500. Or even better two, with a vacuum gauge and a change over valve.
PetiteFleur
Well-known member
My advice - get rid of the standard CAV filter and fit a replacement screw-on-filter head - SO MUCH easier, virtually no diesel spill, no problem trying to fit replacement seals, just spin on the new filter. Replacement screw-on-filter heads available from ASAP or SSL Diesel parts. direct replacement head with UNF threads.
Kelpie
Well-known member
It's a little hard to come by a Racor filter when you're halfway through a cruise on the NW of Scotland.
Now that I know how to actually assemble the filter, I'm not massively bothered about changing the whole housing- I have unusually good access and the filter elements being a tenth the price of a Racor one is quite nice.
One day I will hopefully have a twin drop-in filter setup with a vacuum gauge. But not on this boat.
Now that I know how to actually assemble the filter, I'm not massively bothered about changing the whole housing- I have unusually good access and the filter elements being a tenth the price of a Racor one is quite nice.
One day I will hopefully have a twin drop-in filter setup with a vacuum gauge. But not on this boat.
PabloPicasso
Well-known member
Can you show a link to such a set up, with details
ghostlymoron
Well-known member
That's a very expensive element change! Generations of mechanics have changed these without problems - admittedly it's a bit more tricky on a boat but I've done it several times without leaks.
The one I DID find difficult was the secondary filter on my MD1 which was tucked up close to the cockpit floor and could only be done by feel. It took two of us to do it.
Stemar
Well-known member
That's the problem with boats, so many of them have such poor access. It's bad enough doing one that requires the skills of a contortionist at routine maintenance time, trying to do it in the dark in a rough sea can quickly become a nightmare.