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Fuel Filter Change Frequency

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
I got to pondering this and did a search on Racor (seemed like a good place to start...) on our site and could not quickly find relevant threads about changing filters, etc.
:confused:
The pondering started with a reading of this lengthly thread on another sailing site. The commentary and pics were interesting.
http://www.ybw.com/forums/showthread.php?t=257917

Anyone here changed to a dual-filter setup with a manifold?

Loren
 

Rocinante33

Contributing Partner
Loren,

That is an interesting discussion which you referenced. Questions it left me with, though, relate to the use of a vacuum gauge to monitor the state of the filter. As they described the vacuum gauge, it is installed on the engine side of the filters. Logically, that could only be true if the fuel pump is on the engine and drawing fuel through the filters by pulling a vacuum. In my system, the facet type pump pushes fuel through the filters. Therefore, it is not so clear cut to me how a gauge could work in my system. Would it require two gauges, one before and one after the filters? Then monitor the pressure drop across the filters to determine their state? If so, how much pressure drop would be acceptable? At what point would a change of filters be indicated?:confused:
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Gauge Location...

Hi Keith,
I have no reference other than the stock installation on our boat, where the Recor is on the suction side, and then the electric lift pump pushes the diesel into the spinn-on filter bracket-mounted on the engine.
The more expensive Racor filter model does have an optional vacuum gauge on the top, so I imagine that most installations for this filter are indeed on the suction side.

From your description your fuel supply is plumbed differently than ours, and after all these years I suppose that could either be original or a modification by a prior owner. :confused:

Anyhow, I was impressed with the one picture in that other thread of the remote gauge location where it could be easily monitored. :cool:

Regards,
Loren
 

Maine Sail

Member III
Loren,

I have worked on a number of boats that had dual switchable filters and they do work but they are very pricey if you buy them pre-made. Personally I prefer a dedicated polishing system, like this one I installed (LINK), which keeps the tank clean so the primary filters don't plug to begin with. Switchable filters are a band-aid approach from an injury you should have never let happen. Switchable filters don't solve fuel problems, they only give you a new clean filter with the flip of a valve so you can then plug it up too.

Racor wants to see pumps plumbed on the suction side for the most efficient water removal and also to facilitate the use of a vacuum gauge. The problem with vacuum gauges is that in many installations I see the owners have no idea how to use them or how to accurately monitor them. Drag needle gauges make this task much easier and more reliable.

As for change outs I prefer not to let them go more than two years, regardless of how dirty they are. The filter paper can be degraded by any moisture in the fuel. I have seen a two filters blown out over the years and the owners never knew until the engine stopped. None of these were Racor filters but one of them was a Yanmar on-engine filter that had literally collapsed. I have no idea how long it had been in there but do know it had been at least the three plus years my neighbor owned the boat.

For our boat, with its polishing system, I will still change them at year two even though they will be perfectly clean. Filters are cheap and engines are expensive. The polishing filter will get changed at about 7-8 inHG of vacuum or every two years.


This drag needle gauge is from Sailors Solutions and made especially for them. It is a better drag needle gauge, quality wise, than the Racor with drag needle and it costs less money too. No need to be running at WOT under load to monitor your vacuum gauge as the drag needle stays at the highest vacuum sensed.

131336757.jpg
 
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rwthomas1

Sustaining Partner
I have driven diesel vehicles for years and NEVER changed a fuel filter until it was dirty. I have a Racor 500 series on the boat, way oversized for the application. Put clean fuel in, keep algae away and the fuel filter will always be clean. Years and years of diesel operation without issue. RT
 

rwthomas1

Sustaining Partner
Frank, never had an algea issue in any vehicle I've owned. Good filtration, good fuel, etc. If I did, Biobor would be my first choice. RT
 

Maine Sail

Member III
Frank, never had an algea issue in any vehicle I've owned. Good filtration, good fuel, etc. If I did, Biobor would be my first choice. RT


Fuel problems in vehicles are far more rare than in boats, especially sail boats. When I worked on big yachts we had huge inspection ports in the tanks and they were always clean but hey we burned over 100 GPH so it never had a chance to grow bugs but the fuel dock loved to see us pull up.

Sailboats on the other hand are notorious for growing gunk in the tanks. Our boat had been treated religiously for over 30 years with biocides and for the last 15 with SolTron/StarTron. The PO is a good friend and I have known and sailed on the boat since well before we bought it. Despite his desire to treat and keep the tank clean when finally pulled it still looked like hell.

123034832.jpg

123035293.jpg


After a deliver back in the 90's when we literally ran out of clean filters, cause they kept plugging, I decided to always try and keep my fuel as clean as possible.

Believe it or not his boat would still idle for a bit before it died..
105819198.jpg
 
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rwthomas1

Sustaining Partner
I am well aware of the much higher incidence of fuel related issues on boats, especially algae. I just have not ever had a problem. Maybe I am lucky?

I had to replace the fuel tank on my E38, original tank corroded out at the bottom. I had to cut it with a sawzall to get it out of the boat. The interior of this tank had that tar-like discoloration in the bottom 1/4 of the tank but there was NO debris, crap, crud, etc. to scrape out. Very clean for an original tank. Either the PO was religious about fuel cleanliness or maybe he paid for fuel polishing regularly.

I've seen and helped clean out many filters clogged with algae and crud on other boats.

I don't change fuel filters just to change them. If the fuel is flowing and the filter is clean, why touch it? I've never seen ANY water or crap in the bottom of my Racor 500.

RT
 
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Dan Morehouse

Member III
I have a 1981 e-38 that spent most of its life in San Diego. I recently installed an inspection panel on top of the fuel tank. It's possible the fuel had been polished, but there's no way the tank could ever have been physically cleaned out, since the biggest hole in it was about 2" in diameter...and had been covered with a sheet metal patch fastened with sheet metal screws. This hole was about the same size as the one where the fuel gauge was mounted, so maybe they mis-cut it @ the factory & then covered it. Anyway, there was about a half inch of grit in the bottom of the tank, covering an area of maybe half a square foot. No slime, but the bottom was also thinly coated with a hard, tarry substance which clung tenaciously to the surface & resisted scraping off cleanly. I had an engine quit on a Catalina 42 in the San Juans that was gunking its filters about every 3 hours of running time, and thus my paranoia over the state of my tank. Knowing exactly what's in it (and NOT in it) makes me far more confident in my Racor.

Dan Morehouse
1981 E-38 "Next Exit"
 

tilwinter

Member III
Black sediment in diesel tank

I don't think that the black sediment is biologic. Personally, I doubt algae ever grow in diesel fuel unless there is water in the tank, which is a separate problem and should be addressed as such.

Diesel fuel contains unstable hydrocarbons which oxidize and aggregate, creating the black sticky substance on the bottom of the fuel tank. Some refer to this substance as asphaltene, although I have seen others dispute the actual chemical composition.

There are additives that slow the oxidation and also keep the oxidized hydrocarbons in solution, delaying the process.

I have used a high pressure polishing service to clean my tank every few years.

Those of you who are luckly can wipe off the bottom of the tank through an inspection port.
 
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