How do you determine the proper Water separator sizing for a 1998 OX66 250 HP? Is it based on GPM of fuel flow, micron size? Trying to ensure I don't replace the element with one too restrictive. Thanks.
Inline Water Separator Sizing OX66
- Thread starter Patsy Mac
- Start date
Patsy Mac said:
It's not super important. Most separators/filters will pass plenty of fuel for your motor. The exact supply rate is complicated since it depends on factors like line size, line length, fittings( especially angles), etc. Bottom line is that your motor doesn't consume much more than 25 GPH at WOT and most typical filters with 3/8 inch fittings are rated at about 90 GPH.
Now the issue of 10 micro versus finer filters is often debated. There are filters on the motor that will stop particles smaller than 10 micron so I am in the camp that says a 10 Micron separator/filter is all you need
Agree with everything above (10 micron) and will add... Sometimes it's best to not overthink things. You'll end up wasting lot's of time and energy researching and second guessing yourself. Think of it this way: Is your current filter working fine for you? Then replace it with the same one.
Late as usual, and totally disagree with the above posts. Injector screens, the VST HP pump screen, and VST regulator all use screens in the 2-3 micron range. The ethanol "scrubs" the gas tank creating black crud that passes through the 10 & 15 micron filters and usually clogs the VST pump filter. Why not stop the dirt from entering the engine in the first place. Racor makes a 2-micron filter that is a direct replacement for the Merc or Yam filter. Flows 60-gal/hour. I've had fuel problems on all the boats in my sig. Fix the problem and use these filters and don't have to remove the VST every year.
Yes, there's more than one school of thought on the subject. "Generally" speaking, you start with a course filter and work your way down to the final filter. If you start with a fine filter, it can get plugged up much sooner than it should and could leave one stranded, although carrying a spare filter can solve the stranded part.
For what it's worth, my VST tank and VST filter has been absolutely spotless for the 3 seasons that I've had this boat - zero fuel issues (starting with a 10 mic, boat-mounted filter). The VST tank takes less than 30 minutes to remove - easy enough for once a year piece of mind. But simply draining the tank and checking fuel quality should suffice 99% of the time as anything starting to clog the VST filter will likely also be floating in the fuel.
For what it's worth, my VST tank and VST filter has been absolutely spotless for the 3 seasons that I've had this boat - zero fuel issues (starting with a 10 mic, boat-mounted filter). The VST tank takes less than 30 minutes to remove - easy enough for once a year piece of mind. But simply draining the tank and checking fuel quality should suffice 99% of the time as anything starting to clog the VST filter will likely also be floating in the fuel.
DennisG01 said:
In ten years, I have never replaced the VST screen. I inspected it once and gave it a cleaning. I replace the 10 micron separator every season and the on board filter very 4 or 5 years. My experience with several Series II motors at my club is that VST issues often show up as dropping revs issues and not breakdowns. Most issues I have seen at the club relating to fuel have been water that got into the tank, usually through the fill cap. It is amazing how often I see Perko combo (fill and vent) caps that are missing the o-ring.I replace my o-rings every now and then.
I do not add stabilizers during the boating season but I do use Valve-tech fuel. Contrary to a lot of folks opinion, it does contain ethanol but it has some additives for marine applications.
This year it's time for a new on board fuel filter cartridge. It's been 5 seasons
One thing I do try to avoid is fueling up early in the season when the fuel dock tanks has gas that has been sitting all winter.seasick said:In ten years, I have never replaced the VST screen. I inspected it once and gave it a cleaning. I replace the 10 micron separator every season and the on board filter very 4 or 5 years. My experience with several Series II motors at my club is that VST issues often show up as dropping revs issues and not breakdowns. Most issues I have seen at the club relating to fuel have been water that got into the tank, usually through the fill cap. It is amazing how often I see Perko combo (fill and vent) caps that are missing the o-ring.I replace my o-rings every now and then.
I do not add stabilizers during the boating season but I do use Valve-tech fuel. Contrary to a lot of folks opinion, it does contain ethanol but it has some additives for marine applications.
This year it's time for a new on board fuel filter cartridge. It's been 5 seasons
I agree. I've heard that some replace the VST filter every year. I personally don't see the point in doing that - for the most part, it can be cleaned if it's just a little dirty. I understand the mentality of "better safe than sorry", and maybe for some people that don't really get into doing much of their own maintenance, it's makes sense. Afterall, by the time you pay someone to disassemble the tank and clean the filter, it might be about the same money as just replacing the filter. Although... given how much that silly little plastic filter costs (in YamBucks), maybe it still makes sense to pay someone to clean it!
Lately, I've been looking into "alternate" sources for the filter, pump and such. Nothing "marine" is cheap, but they are just CRAZY expensive! I believe Merc makes/uses the same setup in some of their engines and it's less expensive. Sierra also makes good stuff.
For years, I've always replaced the boat-mounted fuel/water separator as good PM. Given the filter is only about $10/$15, no big deal. But last year I added a vacuum gauge to the filter head mount (I think it was less than $20). This will now tell me the "health" of the filter and when it should be changed. It wasn't really to save money (although in the long run I will), it was more because I like gauges! :mrgreen:
Ethanol has the double whammy. The older, pre-ethanol, boats get that fine dirt that clogs low speed jets and HP pump filter and injector screens. I've never heard of a newer boat with this problem. The second problem is water entering the tank, as mentioned. I don't think any filter can stop the problems with phased gas. The 2-micron Racor is up to about $26 and requires a a 1-time purchase of the separator bowl. Cheap insurance IMHO.
Parthery
GreatGrady Captain
Another vote for the 10 micron filter here. I change mine 2x a year. I'm diligent with PRI-G and Ring Free. And I buy my fuel at street stations where I know it's fresh. The major station near the ramp is now carrying Ethanol Free 87 and its the same price as Premium so I've been buying it, but the additives still go in every time.
It's not worth the risk of an explosion. There are ways to eliminate the explosive vapors but I am not going to encourage that approach.Tucker said: