[John Robertson Posts: 5136 Status: Offline WWW]

There is another problem I've seen with paper cartridge air filters and that is salt. The water evaporates and leave the salt crystals behind - if you can see white stain marks on the filter then that's the salt. Eventually, the filter gets partially blocked.
 
I would recommend that you pipe the air intake from someplace that is always dry and that you change the filter regularly (certainly far more often than the specified period) when using on salt water. As Ian says, an upward run in the pipe with a drain hole at the bottom is good. You can put a long intake pipe on most filters without affecting the engine at all - don't increase the length of the bit from the carb to the filter though!
 
If you want to stop the rusty filter mesh then buy the plastic mesh versions - nothing else will work

[Ian Brooks Posts: 3551 Status: Offline]

Mmmmm - not sure there is anythng fundamentally wrong with a BBV3 Gavin - I think spray generation has as much to do with sea conditions, type of use and driver ability as anything else :-)
 
I think you have probably indentified what happened Jon although we were fairly careful not to get water into the intakes when washing down and the engines had a 20 min dry-off run afterwards. Ithink the cause is possibly a build up of salt on the metal cage leading to a highly corrosive mixture. Any dampness is going to find that and start rusting.
 
This isn't a 'fault', just a note to anyone with a Briggs 35 and a standard air cleaner - I don't think the designers ever really thought about salt laden damp air ! Not really in the design spec.
 
As a separate note, after taking water into the lift engine filter at the Hovershow, I've modified the Honda air cleaner to take air from a pre cleaner in the cockpit.
 
I should add that there is only the very early stages of rusting on our filter - mainly surface discolouration, but I think there is a potential for trouble in the future given the stated filter operating life.

The craft looked pretty reasonable spray-wise when I was looking at it, but having said that there was a pretty fresh breeze and we were doing some slow maneuvering, so spray is pretty much a fact of life.

One suggestion is to add a piece of 2" hose (from the pond section in the garden center) to force the air to travel upwards into the filter - just means that the larger drops fall out via gravity.

Ian

[rossfloyd Posts: 2025 Status: Offline]

Mmmmm - not sure there is anythng fundamentally wrong with a BBV3 Gavin - I think spray generation has as much to do with sea conditions, type of use and driver ability as anything else :-)
 
I think you have probably indentified what happened Jon although we were fairly careful not to get water into the intakes when washing down and the engines had a 20 min dry-off run afterwards. Ithink the cause is possibly a build up of salt on the metal cage leading to a highly corrosive mixture. Any dampness is going to find that and start rusting.
 
This isn't a 'fault', just a note to anyone with a Briggs 35 and a standard air cleaner - I don't think the designers ever really thought about salt laden damp air ! Not really in the design spec.
 
As a separate note, after taking water into the lift engine filter at the Hovershow, I've modified the Honda air cleaner to take air from a pre cleaner in the cockpit.
 
I should add that there is only the very early stages of rusting on our filter - mainly surface discolouration, but I think there is a potential for trouble in the future given the stated filter operating life.

[rossfloyd Posts: 2025 Status: Offline]

I've just checked my air cleaner after our run in the Bristol Channel last weekend and found it to be very damp and the expamet grid that holds the outer element in place is starting to corrode.
 
While the dump valve has clearly been filtering off much of the sea water that came aboard, it looks as if salt deposits have remained on the element and begun to corrode it, which in time might lead to a collapse and blockage.
 
I guess this would be spotted during routine checks and long before there was a problem,  but the filter has a long operating life it might be an idea after a sea trip to remove it and dry the element out so that it dosen't remain wet and shorten its operating life.
 
I would have expected the airflow to dry it out, but we covered well over a mile after coming ashore and there was still water in the filter a week later!  I don't think it got in while we were washing the salt off so it seems it must have been ingested during the trip.  There is a lot of surface rust on the metal grid which wasn't there before the trip,so it looks like salt corosion.
 
Hope this is of help to someone!