NEW FUEL FILTRATION SYSTEM

[bob mitchell]

New Fuel Filtration System

When I got hull 113, aka WILSON, she had been through five owners, the first three which had really looked after her, and the next two which were a disaster. Not only did they not maintain her, but she was in freshwater as well - so I have a lot of rebuilding to do.

The engine, a Ford Osco, runs very well for a short while, so there is reason to be encouraged. The boat was built in 1967, had an engine replacement in the late 70's, and then a supposedly complete rebuild in 1999, and does not have many hours on it, so if I can figure out the problem things may work out.

Looking at the filtration system, I only saw one old filter head with a newer type cartridge filter, with no water bowl, screwed in. There was no way that these were meant to be together, and in fact the old head said " use of any filter besides a Mac voids warrenty" (that's MAC TRUCKS for you youngsters - can I really be this old? - not mac computers or hamburgers!) So since most diesel problems are caused by bad fuel I decided, like I did with the electrical system, to start over from scratch.

SO HERE IS SOME GOOD INFORMATION. After researching for 3 weeks and lots of dead ends I finally found a filter system I could work with. I did not go with Rancor because they changed the cartrige size in 1995 so all pre 95 heads would only work with an adapter kit, which they did not publicize well at all, and there were significant complaints on cruising forums about their later products.

BUT at some point I called Cummins in Cookville,Tn., to find out the micron size on a cartridge I was trying to buy - because the distributor did not have that information, and the Technical Assistant I talked to, Judy Stewart, said that it was "proprietary information". Bizarre -but a least I had a human. I explained to her what I was trying to do and she basically said "here is a 20 micron cartridge with a clear plastic bottom water separator (what I really wanted) that you can get the head and HEAVY duty bracket mount for. (see photo)

FS1242B for cartridge and bowl (about $28, cartridge alone $14)

3930618S for head (about $50 for head and mounting bracket)

256535S for mounting bracket (its 1/4" thick stamped steel)

available from Cummins in Atlanta 1-404-527-7800.

FS 1000 is a 10 micron cartridge that fits same head, has a drain, but no plastic bowl. Both of these cartriges are available at semi truck part dealers. The 20 micron filter traps 96% of particles above 20 micron size, and 79% above 10 microns.

So in the best of all worlds my system would have two in line filters each with a bypass so that when you got in heavy seas and the diesel tank bugs got all agitated, you could bypass the first filter, which with the percentages above will obviously fill up with crud first, and never have to shut the engine down as you changed it. Who knows, might make the difference between on and off the rocks. However, initially I am doing a non by pass run with one filter.

The Ford 172 engine was a tractor engine originally, converted for marine use by two companies that I know of, Osco and Lehman. I have an Osco, but the point is that in tractors the fuel tank was above the engine and gravity fed, while on the boat the two are about even, so I use a "lift pump" in the fuel line to make sure that the fuel injector pump has plenty of fuel. (The above is information I have heard but cannot be sure of its correctness). The lift pump should come after the filters because it breaks the water droplets up into particles that are too small for the filters to separate. The lift pump is the

 

12Volt Diesel Micro Electric Fuel Pump #12D (About $50)

readily available from either auto zone or advanced auto, I can't remember which. I ran across it when I was studying diesel polishing systems. Semi truck drivers are using them for polishing fuel. (cleaning the fuel by circulating in a separate filtration system, maybe while the engine is not even running.) See www.trawlersandtrawlering.com for great discussion on fuel polishing under HOW TO.

So the lift pump brings up the last technical aspect of my filtration system - that of overcoming the different types of threads on the fittings, i.e. avoiding a mismatch of thread types (i would reccommend googling NPT vs NPS threads, and copper "compresion" vs "flanged" vs "sweated"). I had planned to do all copper tubing with "FLANGED" fittings, but I could not find a lift pump that was set up for copper, so this attempt will be using 5/16" rubber marine grade fuel lines. That meant I had to adapt all fittings for "hose barbs". So the filter head, which had 7/8" female National Pipe Threads (tapered, not compressional, and must have teflon tape or liquid for good seal) had to have an "insert" or "adapter" to bring it down to a smaller hole that would take 5/16" I.D. size fittings. (The head intake and exit openings are for semi truck size fuel consumption, in case you are wondering why they are so big). I also added a shut off valve ($20 for needle valve - I think yacht standards discourage levers), and a few direction changers. The line going into the fuel injection is a "compression" fitting  (note the tapered shoulder in the photo) and does not need teflon.

       COMPRESSION FITTINGS, FEMALE AND MALE

                                   

                                                      NPT THREADED HOSE BARB          INSERT ADAPTER

         

So all fittings were National Pipe Thread (NPT) and hose barbs with stainless clamps except the final compression fitting.  As usual I am not trying to explain everything, but am only pointing out some things to consider. In no way should anyone take this information as totally reliable.

 

[bob mitchell]

UPDATE: A couple of years have gone buy, I am totally rebuilding my engine - its finished, I just have to put it back together. What an incredible amount I have learned about the Ford Osco 172/192. Along the way I picked up an original Roosa Master

(the type of fuel injection pump) secondary filter head and bracket that mounts on the engine. The filter element is a Cummins FF138 or a NAPA 3165 or a WIX 33165. All of them cost at least $17 bucks at the local auto parts but I ordered mine, the NAPA GOLD, from FleetFilter.com  in Brenham, tx. (1-866-3458) for $8.87 a piece. So my system now consists of the 20 micron primary system with water separator and visible bowl, and a 10 micron secondary filter (original) mounted on the engine.

[michael soto]

Hey Bob,

 

I have those shoes too!  Just kidding.  I like this one.  I wish I could go fix my fuel filter, lift pump problems but I don't have any yet.  Your threads are amazing I call you guru.