Help Me With Water Seperator Question

[jdsmith]

I know what the purpose of a water seperator is but can someone explain to me how it works and how I know when to replace it and which type should I use for my 2002, 150, Johnson, 2 cycle engine? Thanks

 

[Average Joe]

Basically the water is heavier than the fuel and it seperates and goes to the bottom of the seperator. People will say you should change it every 50-100 hours. Personally I think if you use it on a regular basis 50hrs is overkill and I usually go 75-100hrs.

You can install the type of seperator that has a clear bowl on the bottom if you want to see if and when there is any water.

 

[Strikezone]

I've never had a water issue and change my filter every year. I do keep a spare on board just in case. I switched to the Yamaha 10 micron a couple of years ago.

 

[gradyfish22]

Yamaha filters and Racor typically recommend 100 hr max usage, not sure about other brands. Typically you will get about 80-100 hrs or 1 season out of a fuel water seperator. If your gas sits for two weeks at a time, I would highly advise getting a racor 2micron clear bowl, more expensive but it will let the least amount of junk through and keep your engine in better shape. The clear bowl allows you to see water physically collecting, warning you of an issue you need to attend to before it does any major damage. I also highly recommend carrying a spare, it will allow you to get in if one clogs and your engine is bogging down or if you see water, you will end up using it after 100hrs or a season anyways so it will not go bad and is not wasted money, it will be used anyways.

Basically the external fuel water seperator filters allow your fuel to be filtered at a high rate and when debris is caught being that the bowl and fllter are much bigger then the filters on the engine, typically you will still be able to run without issues, whereas the filter on the boat is small and the smallest particles can cause major issues. The external filter also gives your engine a big safety shield since you now have 2 lines of defense from getting water or debris to the engine, both the filter on the engine and the external seperator, hopefully it never gets to the engine, that is the idea. Changing the external filter is easy as long as you mount it where there is space to access it. It really is a smart thing to add especially since most gas stations now have ethanol in the fuel which allows water to form much quicker, as well as the ethanol taking off the tarnish from an aluminum tank which will get caught in a filter, these are things ou never want reaching your engine unless you want headaches and big bills.

 

[seasick]

The 2 micron filter is no more effective at separating water than the 10 micron. It does filter out smaller particles of sediment, dirt etc. Water molecules are many many times smaller than 2 microns.

While it is true that separators work because water is heavier than gas and the water in the filter will drop to the bottom, if the flow through the filter is fast enough, the water won't have time to fall to the bottom. In addition,since the bottom of the filter only holds a few ounces, it doesn't take a lot of water before it passes through the filter.
It is reasonable to guess that a smaller boat motor will get better 'filtering' than a larger motor simple because the flow rate is less and the fuel 'sits' in the filter longer

Ethanol gas ( 10%) can absorb 0.5% water by volume. That water is burned off in the motor. Once there is more than 0.5% water, it will settle out to the bottom of the fuel tank. If it gets pumped throught the filter, any amount greater than the bowl volume will end up in the engine ( and that assumes that the filter got all it theoretically could)
For a 100 gal tank, 0.5% is 1/2 gal of water. The bottom line is that if you get a bad tank of gas with a lot of water, the filter isn't really going to make a difference.

 

[SlimJim]

The 2 micron filter is no more effective at separating water than the 10 micron. It does filter out smaller particles of sediment, dirt etc. Water molecules are many many times smaller than 2 microns.

While it is true that separators work because water is heavier than gas and the water in the filter will drop to the bottom, if the flow through the filter is fast enough, the water won't have time to fall to the bottom. In addition,since the bottom of the filter only holds a few ounces, it doesn't take a lot of water before it passes through the filter.
It is reasonable to guess that a smaller boat motor will get better 'filtering' than a larger motor simple because the flow rate is less and the fuel 'sits' in the filter longer

Ethanol gas ( 10%) can absorb 0.5% water by volume. That water is burned off in the motor. Once there is more than 0.5% water, it will settle out to the bottom of the fuel tank. If it gets pumped throught the filter, any amount greater than the bowl volume will end up in the engine ( and that assumes that the filter got all it theoretically could)
For a 100 gal tank, 0.5% is 1/2 gal of water. The bottom line is that if you get a bad tank of gas with a lot of water, the filter isn't really going to make a difference.

I disagree, a 2 micron filter with racors and a bowl will work better on a HPDI engine then a 10 micron filter. It depends on the engine.

 

[seasick]

The 2 micron will work better at what?
Separating water or just particles? I have not seen any real data on the effectiveness of the filters.
If you have very dirty gas (particles of dirt, sludge, slime, sediment etc), the 2 micron will trap the smaller ones. It will also clog up faster. Of course if the fuel is 'dirty' enough any filter will clog up. Here is what I would like to see as a test.
Mix several measured batches of gas/water mixture, sat .5%, 1%, 5% and 10%.
Pump the mixtures through various filters, manufacturers, type etc. using typical outboard pressure and flow rates. Measure the filtered fuel and analyze the water content. That should tell us what these filters do.

perhaps one of the boating magazines might do such tests.

 

[Seahunter]

Its absolutely nuts to change filters based on calendar intervals. A filter’s replacement interval should be determined by a pressure drop in excess of motor manufacturers specification.

Do yourself a favor and install some sort a pressure indication device on the fuel line. Racor makes one that plugs right into the filer head. You can get a simple screw in for $50 or you can go all out and install a sensor the has a remote gauge that you can install at the dash. With filter costing $20-$25 apiece, it doesn’t take long to recoup the money for the sensor by not replacing perfectly serviceable filter based on time.

 

[Islander]

The "internal" fuel filter on my Yamaha outboard sits inside a clear plastic cylinder. It has a red ring float that sits on the bottom, but by design will rise or float up when water is present at the bottom of the bowl.

I assume that monitoring this float periodically will provide a warning that the external fuel filter is no longer effective at separating water from fuel. But I nonetheless change the external fuel filter per Yamaha recommendation.

 

[seasick]

The "internal" fuel filter on my Yamaha outboard sits inside a clear plastic cylinder. It has a red ring float that sits on the bottom, but by design will rise or float up when water is present at the bottom of the bowl.

I assume that monitoring this float periodically will provide a warning that the external fuel filter is no longer effective at separating water from fuel. But I nonetheless change the external fuel filter per Yamaha recommendation.

That filter holds about 2 ounces of liquid. The main filter holds a lillte less than a quart. Their prupose is not to protect from a lot of water in the gas. They are there to filter out mild moisture/condensation. If you get a bad load of gas that has a lot of water, that ring will rise in a hurry. the motor will die before you have a chance to check the ring.

 

[seasick]

Its absolutely nuts to change filters based on calendar intervals. A filter’s replacement interval should be determined by a pressure drop in excess of motor manufacturers specification.

Do yourself a favor and install some sort a pressure indication device on the fuel line. Racor makes one that plugs right into the filer head. You can get a simple screw in for $50 or you can go all out and install a sensor the has a remote gauge that you can install at the dash. With filter costing $25-$25 apiece, it doesn’t take long to recoup the money for the sensor by not replacing perfectly service filter based on time.

That's the sanest thing I've heard in a while! Great tip.

 

[merlin25]

Seahunter - I've been looking for the Racor pressure guage and can't find one. Any advice on a place that sells one? Also what kind of pressure range are we looking at for the gauge?

 

[Seahunter]

Seahunter - I've been looking for the Racor pressure guage and can't find one. Any advice on a place that sells one? Also what kind of pressure range are we looking at for the gauge?

Here is the screw-in
http://www.go2marine.com/product.do?no=160213F&WT.mc_id=gb1

Dash mount
http://www.go2marine.com/product.do?no=87263F

 

[merlin25]

thanks

 

[BobP]

Seahunter, you can get the racor filters a lot cheaper on the internet, I've paid half theh price of a well known marine outlet, very well known.

I have no problem paying more at the local brick and mortors, but not twice the price for the same exact item.

PM me if you have such a need.

 

[richie rich]

Bob, spill the beans...where did you get em'?

 

[BobP]

All right all right, been using them for several years now -

The price did go up recently though, at marinefilters.com, I get them 4 at a clip, arrive at home in 3 days, they ship out of the gulf coast somewhere by (green machine ??)

I'd suggest you google the Racor part number and see what comes up these days.

The hours recommended for replacement can only be based on quality of fuel supply and how much fuel motor requires, both of which can't be predeterined by filter manufacturer so don't know what 100 hr recommendation is based on..

 

[richie rich]

Thanks Bob.....looks like around $5 savings per replacement filter over my best deal locally!