I changed out my Racor fuel filter this weekend after it was recommended I use the "10 micron twist on replacement filter unit" rather then the "2 micron unit" for my Universal M-18 two cylinder diesel. The orginal filter was the 2 micron unit. I wondered about the choice later thinking the 2 micron would certainly do more in removing smaller particles, but opted on the 10 micron as suggested. What is the thought on filter micron size in fuel filters here? Should a less porous filter material be used to get the gunk out of the system like the 2 micron unit, or is the larger preferred? Thanks Bob
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Two Filters
Generally you have two filters. The first is the 10 micron near the tank and a 2 micron near the engine. This keeps the 2 micron from filling up instantly from bad fuel.
Generally you have two filters. The first is the 10 micron near the tank and a 2 micron near the engine. This keeps the 2 micron from filling up instantly from bad fuel.
The Good, The Bad, and The Ugly
Sometimes when trying to reason things out, when what seems like a really good solution, there are unintended consequences. Sicking to the filter question and not getting sidetracked with using the Iraq war as an example, the fine micron filter taking out the crud seems like a solution. However, there is more head-loss with the finer filter and as it fills up with crud and the force required to suck the fuel through the filter increases, this puts proportionally increased pressure on the fuel pump diaphragm. With a harder working diaphragm there becomes increased likelihood of failure. For example, just a small pinhole leak can cause fuel to enter the oil pan and result in a runaway engine. The best solution is to keep the fuel clean, keep the tank clean, and follow factory recommendations otherwise you'll be chasing problems.
Sometimes when trying to reason things out, when what seems like a really good solution, there are unintended consequences. Sicking to the filter question and not getting sidetracked with using the Iraq war as an example, the fine micron filter taking out the crud seems like a solution. However, there is more head-loss with the finer filter and as it fills up with crud and the force required to suck the fuel through the filter increases, this puts proportionally increased pressure on the fuel pump diaphragm. With a harder working diaphragm there becomes increased likelihood of failure. For example, just a small pinhole leak can cause fuel to enter the oil pan and result in a runaway engine. The best solution is to keep the fuel clean, keep the tank clean, and follow factory recommendations otherwise you'll be chasing problems.
I used a 2 micron filter on a Perkins 18HP
for 100 hrs. cause it was "at hand" when I changed the filters. I carried a spare 10 micron in case it clogged, in use it seemed to work fine but there was slightly more "crap" collected in the filter bowl. The boat runs year round and gets more than 100 hrs/year and fresh fuel every 6/7 months (max). Seems that clogging and increased pressure could result if the fuel had more time sitting in the tank. Back to a ten micron again, free filter wasn't worth the bother of wondering if it would plug up.
for 100 hrs. cause it was "at hand" when I changed the filters. I carried a spare 10 micron in case it clogged, in use it seemed to work fine but there was slightly more "crap" collected in the filter bowl. The boat runs year round and gets more than 100 hrs/year and fresh fuel every 6/7 months (max). Seems that clogging and increased pressure could result if the fuel had more time sitting in the tank. Back to a ten micron again, free filter wasn't worth the bother of wondering if it would plug up.
I have a 2 micron on my racor filter also
It was what came with the boat and I think the engine (M35B) fuel filter from Westerbeke is 2 micron also. Though Racor would suggest a 10 or 30 micron for the Racor if you have a 2 Micron on the engine then even Yes it is counter intuitive for me to have two seperate filters with the same Micron filter size and I was planning on replacing the 2 Micron Racor filter when it needed it, but is has 600+ Hours and it and still doing fine. I have put a vacuum guage on the Racor filter and I monitor it once in a while and the needle barely moves so its not a bit clogged at all and not harming my pump. Now I am the first to admit I must get great fuel. (knock on wood...knock...knock....knock..) Fuel in the warmer climes such as Florida etc probably have a higher chance of "crud" than what I get. I also make sure I have no water in the tank to keep the potential for problems down. Obviously if I get a "bad batch" the 2 micron will clog up quicker than if I had a 10 micron, but I will live with it for now. Just an FYI You can also get bigger spin-on filters from Racor (they come in different sizes) if the longer length can fit on your boat. For instance a R20T is rated @ 20 Gallon per hour and 10 micron filter and will handle and hold more "crud" before clogging than a R15T (15 gallons per hour)
It was what came with the boat and I think the engine (M35B) fuel filter from Westerbeke is 2 micron also. Though Racor would suggest a 10 or 30 micron for the Racor if you have a 2 Micron on the engine then even Yes it is counter intuitive for me to have two seperate filters with the same Micron filter size and I was planning on replacing the 2 Micron Racor filter when it needed it, but is has 600+ Hours and it and still doing fine. I have put a vacuum guage on the Racor filter and I monitor it once in a while and the needle barely moves so its not a bit clogged at all and not harming my pump. Now I am the first to admit I must get great fuel. (knock on wood...knock...knock....knock..) Fuel in the warmer climes such as Florida etc probably have a higher chance of "crud" than what I get. I also make sure I have no water in the tank to keep the potential for problems down. Obviously if I get a "bad batch" the 2 micron will clog up quicker than if I had a 10 micron, but I will live with it for now. Just an FYI You can also get bigger spin-on filters from Racor (they come in different sizes) if the longer length can fit on your boat. For instance a R20T is rated @ 20 Gallon per hour and 10 micron filter and will handle and hold more "crud" before clogging than a R15T (15 gallons per hour)
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