Fuel filter question

[Ragbagger]

As a new Hatteras owner, since last fall, , I am doing all the annual maintaince. I am an accomplished amature wrench. I still need to replace the primary fuel filters. The Racor 1000ma replacement elements come in 2mils, 10mils, 20mils and 30mils. I did a search and found the secondary filters are 7mils which I have already replaced. I read various stuff on which ones to use for the primary. I am thinking the 20 mils element. Is this a good approach?

Also, do I need to fill the filters up with fuel before I install? I didn't fill the secondaries and the engines picked up ok after hesitating a little. Looks like a lot more volume in the primary filters.

 

[REBrueckner]

You can "search" on this topic from the top headings on this page for lots of prior posts/discussions on this subject. It's always best the fill the filter cannisters with additional clean fuel to the top after changing filters. My 8V71TI's are very sensitive to secondary fuel filter levels, not to primary filter fuel levels. And while at the cannisters, always drain a bit off to eliminate any "stuff" collcted at the bottom.

The standard approach is to use about and smaller micron, 2 or 5, on secondary or OEM and something larger on primaries. If you have vacuum gauges on your primaries, you can use a smaller micron filters on the primaries as well. Maybe you'll get slightly cleaner fuel to your engines overall. A danger in using 2 microns on primaries is that if partially clogged/obstructed with crud they can limit bypass fuel flow used for lube and cooling and run operation may appear normal, but injectors may wear prematurely. Without vacuum gauges, many use 20 micron at primaries. In theory, the larger micron size traps larger stuff, the secondaries smaller, and overall fuel supply MAY be better maintained. Or use whatever you small size you want and change them frequently.

 

[Traveler 45C]

Do the search and spend the time to sift through it all. There is a lot of info on this subject posted in these pages. If you send your email address, I’ll send an excellent paper on multi-step fuel filtration that I pulled from another forum. traveler45c@msn.com This offer is extended to all.

On my 871’s, I use a 30mic in the Racors, a 20mic on eng pri and a 7mic on eng sec.

There are many benefits to using multi-step filtration. A good 30mic pri filter element will filter 98% of particles down to 2mics! Your 7mic sec is there for the other 2% that may get through. Most of the crud will be caught by the pri and if you’ve got vac gauges you’ll be able to tell ahead of time if your system is clogging. Change the sec at the same time you change the pri and your good to go.

Others use a 2mic pri for convenience reasons; it’s easier to change than the on eng sec, however it may likely clogs more frequently.

Is there anyone out there using multi-step filtration that ever had a sec clog?

You should fill the secondaries before installing and fill the Racor after the element is in place. I use auto transmission fluid (ATF). It’s cleaner than diesel and has detergents that’ll clean the injectors. Diesel Kleen can be used also. The problem with filling the filters with diesel is that you have no way of knowing how clean it is. You’re pouring in unfiltered fuel effectively bypassing the filter and sending it on to your engines.

I keep a few gals of ATF on board incase I’ve got to change filters underway. ATF stores better than a bucket of diesel that sits in the bilge for years.

 

[Will]

I use 30 Micron filters in the Racor primaries on the 6-71s but order the AC secondary and tertiary filters based on the number on the canister decals. Therefore, I don't know what they are. Regardless of vacuum gauge readings, all are changed about every 200 hours which is probably too often.

I once had a problem where one of the engines started loosing RPMs while the vacuum gauge for the Racor was reading normally. I realized that the secondary and tertiaries were clogging thus reducing the vacuum reading. Changing all three filters brought things back to normal.

The Primary for the generator is a 2 micron filter which requires changing about every 50 hours. Although this is too frequent, it avoids me having to change the secondary and tertiary filters on the generator which are really hard to get to.

Will

 

[Brian Degulis]

Hello Raggbager

I've mentioned this before and take it for what you think it's worth but in my opinion filling your fuel filters with anything but fuel is just plain dumb. The engines not meant to run on pure aditive and ATF is even worse it's to thick you may get away with it but your injection system is not designed to pass a fluid of that viscosity. And why on earth anyone would want to do that is just beyond me it's not like it's some tecnlogical challenge to find clean diesel fuel.

Brian

 

[Traveler 45C]

ATF is even worse it's to thick you may get away with it but your injection system is not designed to pass a fluid of that viscosity.

Interesting point on the viscosity. Do you have any data to support that the injectors are damaged by this practice?

Mechanics have been using ATF in the filters for decades. When I change mine, I’ve got close to 2 gals of ATF in the filters. When I crank up I’m burning straight ATF or DK, whichever I’m using, for 3-4 mins (it takes that long to pump through at a .9gal/min@1200rpm flow rate or assuming ½ of that at 600rpm, .45gal/min). During that 3-4mins (warm eng) there is no smoke and the engs run fine. I ‘get away with it’, so do many others.

ATF/DK is more storable than diesel. They’re both cleaner and you get the added benefit of an injector cleaning. That’s hard to beat.

BTW, when filling the Racor, make sure that you pour along the outside of the element to ensure that whatever you use will be filtered properly.

 

[yachtsmanbill]

I use 30s in the racors and 7s on the secondaries. When I do the racors, I empty the unit down to the bowl and wash it entirely. I pre fill the secondaries.
I use a new dedicated fuel can with fresh fuel from the gas station to prime. Before final tightening, I give a few pumps on the primer for 100% prime. Never even a stumble. ws

 

[REBrueckner]

For filter refills I carry a yellow plastic five gallon "diesel" container aboard. I keep two or three gallons and change it every other year or so while refueling at a big volume source, like SEAFUELS in New Bedford, Mass.

Adding fuel to a filter puts fuel into the cannister on the fuel supply side...right?? so before the added fuel gets to the engine, the filter does it's job as normal.....that's why you should (a) drain off crud first, (b) remove the old filter, (c) add the flter, (d) refill with clean fuel in that order.

Or am I missing something?

 

[Traveler 45C]

When refilling a Racor after a filter change, pour the fuel down the outside of the filter element, not the center. Fuel is sucked through the filter element from the outside (where the crud accumulates) to the inside. The inside/center is the eng side of the filter element. When you put the lid back on it makes physical contact with the element isolating the unfiltered fuel (outside of the element) from the filtered fuel (inside of the element).

Make sense?

I remember reading a study on diesel fuel, I think it was a DD paper or one of Tony Athens that stated diesel should only be stored for 100 days, after that it starts to break down.

One of my posts above contained a statement that was not fleshed out as well as it could have, sorry. It’s fixed.