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Old 25-04-2013, 06:07   #16
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Re: Yanmars and 2 Micron filters in Racors?

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Originally Posted by CarlF View Post
It's always possible that the stuff came from the tank. The seas were sloppy. But this was the first fuel problem ever for this boat (I use biocide at each fill). I'm still surprised how clean the 10 micron Racors looked with a completely clogged secondary.

Thanks for all the response. It looks like using 2 micron Racors is a reasonable approach given my setup.

Carl

Generally the engines are spec'd to run with a given set of primary and secondary filters... and the specs include the lift pump (suck and push) and injectors (blow/spray).

IOW, the lift pump may not be designed to consistently provide enough fuel to the injectors if the filters are too dense. And the injectors may well be designed to handle impurities that are smaller than specified filter.

IOW2, switching to denser filters may tend to defeat the engine's design specifications.

Depending on how long your fuel tank has been in service (and some other factors)... it might be reasonable to consider polishing existing fuel and/or cleaning the tank as an alternative approach to the problem.

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Old 25-04-2013, 06:17   #17
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Re: Yanmars and 2 Micron filters in Racors?

Ranger42C, Sailboat engines draw so little fuel that even the 2 micron Racor provides way more than enough flow unless it gets seriously clogged. I think the problem many of us face is that the on-engine filter the engine comes with is something like 5 microns in a lot of cases, so if you are running 10 or 30 microns in the primary, the on-engine filter will be the first to plug up in a dirty fuel situation, and the on-engine filter is usually much more difficult to change. Particularly offshore! On my engine that project is usually something I reserve most of a day for, because of the extensive, slow, and often repeated bleeding procedures required. I have to remove the entire cockpit sole just to access the on-engine filter. I can't imagine having to do that offshore.
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Old 25-04-2013, 09:08   #18
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Re: Yanmars and 2 Micron filters in Racors?

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Ranger42C, Sailboat engines draw so little fuel that even the 2 micron Racor provides way more than enough flow unless it gets seriously clogged. I think the problem many of us face is that the on-engine filter the engine comes with is something like 5 microns in a lot of cases, so if you are running 10 or 30 microns in the primary, the on-engine filter will be the first to plug up in a dirty fuel situation, and the on-engine filter is usually much more difficult to change. Particularly offshore! On my engine that project is usually something I reserve most of a day for, because of the extensive, slow, and often repeated bleeding procedures required. I have to remove the entire cockpit sole just to access the on-engine filter. I can't imagine having to do that offshore.

Yep, I understand. I only meant to point out that initial design is often relevant, and fuel demand increases as RPMs increase in any case. And I know that small diesel lift pumps, depending on engine vintage, are sometimes pretty wimpy

Our genset engine is a small Yanmar, rated at between approx 13-24 hp depending on RPMs (and of course in our generator application, only runs at 1800 RPMs). The lift pump is electric, seems to work like a champ, and may not be bothered by en extra dense fuel filter. (And I note Yanmar -- and Kohler -- aren't all that forthcoming about recommended primary and secondary fuel filter densities in all the operations and service documentation I've collected.) The mechanical lift pump on a previous generator wouldn't pull squat, though, and changing to a denser filter could well have failed.

If OPs tank is already known to be fairly clean, if the engine has always performed well on good fuel in the past, and if he's perhaps only taken on one load of bad diesel... polishing the remaining tank full could be a relatively simpel immediate band-aid. As you say , arriving at something that eliminates the need for hard-to-access surgey while underway would be better


-Chris
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Old 25-04-2013, 09:18   #19
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Re: Yanmars and 2 Micron filters in Racors?

I have a pair of 30 micron filters, using a y-valve to allow me to quickly switch to a clean fuel filter should the need arise. After leaving the 30 micron filter, the fuel goes to an adjacent Racor 2 micron unit, then proceeds to the Yanmar 3GM30's small 2 micron filter, located in an impossible spot for service. Large volume, much larger filter element, and location, location, location. There is also a Racor vacuum gauge tee'd off just before the fuel pump, with alarm light and buzzer, to let me know that a fuel filter issue is developing, ahead of time.
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Old 25-04-2013, 09:47   #20
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Re: Yanmars and 2 Micron filters in Racors?

In the same scenario the 2 micron will just clog up faster!
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Old 25-04-2013, 09:51   #21
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Re: Yanmars and 2 Micron filters in Racors?

Your engine manufacturer specifies which micron filter to use. For many older Diesels 10 microns is okay. For newer Diesels they tend to specify 2 microns. I use 2 micron filters in my primary dual Racors because it is so much easier and quicker to flip a handle than it is to change out my secondary filter.

Although a 2 micron will clog sooner, the advantage to using a 2 micron as your primary with a dual filter system is that you will never have to shut down your engine to change out your secondary because it is not going to clog. Not having to shut down the engine ever for a clogged filter is a real advantage.
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Old 25-04-2013, 10:36   #22
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Re: Yanmars and 2 Micron filters in Racors?

The actual micron rating for any filter is a lot higher than the 2 or 10 or 30 micron rating published for the filter. There are flow rates and %'s etc. that have 5-7 micron objectes getting thru 2 micron filter elements. You should probably use as small micron rating as you can get and hope your filter is big enough to handle some clogging. Its not just clogging filters anyway. Some of that stuff in your fuel is abrasive and wears out very $$ stuff.
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Old 25-04-2013, 11:05   #23
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Re: Yanmars and 2 Micron filters in Racors?

Quote:
Originally Posted by CarlF View Post
It's always possible that the stuff came from the tank. The seas were sloppy. But this was the first fuel problem ever for this boat (I use biocide at each fill). I'm still surprised how clean the 10 micron Racors looked with a completely clogged secondary.

Thanks for all the response. It looks like using 2 micron Racors is a reasonable approach given my setup.

Carl

That was my experience. the Racor filter looked clean. the 2 micron engine filter was BLACK. In my case my problem was accellerated by using a biocide NOT recommended by Yanmar/Mastry, and then following its instructions to shock the tank, which deposited a whole lot of new debris right at the fuel pickup.

I do recommend a little chat with the manufacturer of your engine.
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Old 30-04-2013, 06:33   #24
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Re: Yanmars and 2 Micron filters in Racors?

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And Yanmar doesn't say what the micron size is on this filter.
In my Yanmar Service Manual for the 1GM10(C) thru 3HM35(F)(C) engines on page 3-29 [the fuel filter section] it says the filter mesh is 10 to 15 microns for the little filter mounted on the engine. You might look at the similar section of your manual. It may list the filter specifications.
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Old 30-04-2013, 06:54   #25
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Re: Yanmars and 2 Micron filters in Racors?

....and is the air intake filter/screen clean?
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Old 09-05-2013, 09:35   #26
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Re: Yanmars and 2 Micron filters in Racors?

I use a 2 micron filter element in the port side of my dual Racor setup. There is a 10 micron element on the starboard side.

If the port side clogs up, I can switch to the coarser filter, although I am, of course, aware, that this could simply mean that the primary filter will take the hit. I guess if that ever happens, I will change out the 2 micron filter pronto.

The primary filter on my engine is not hard to get to and I have no doubt that I could change it at sea. The disadvantage, of course, is that the engine has to be shut down, and then bled afterwards, to change the primary.
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Old 10-05-2013, 16:11   #27
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Re: Yanmars and 2 Micron filters in Racors?

specs on my GM series from service manual 10-15. did note when adding extra filter to my engine that the instructions were plain about the filter being after the fuel pump & not before. added electric pump with a low pressure switch no problems for 10yrs except an issue with leaks at the banjos on the great yanmar filter!! caused by bolts being too long on the out port.

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Old 10-05-2013, 23:22   #28
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Re: Yanmars and 2 Micron filters in Racors?

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Originally Posted by CarlF View Post
And Yanmar doesn't say what the micron size is on this filter.

Carl
I emailed Yanmar and they tell me the engine mounted filters (secondary) are 5.
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Old 10-05-2013, 23:31   #29
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Re: Yanmars and 2 Micron filters in Racors?

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Originally Posted by Roy M View Post
I have a pair of 30 micron filters, using a y-valve to allow me to quickly switch to a clean fuel filter should the need arise. After leaving the 30 micron filter, the fuel goes to an adjacent Racor 2 micron unit, then proceeds to the Yanmar 3GM30's small 2 micron filter, located in an impossible spot for service. Large volume, much larger filter element, and location, location, location. There is also a Racor vacuum gauge tee'd off just before the fuel pump, with alarm light and buzzer, to let me know that a fuel filter issue is developing, ahead of time.
Are not these filters movable. Why do you guys put up with this. Just move the secondaries to an easy access location.

BTW the higher pressure IP's need a smaller micron due to the tolerances in the pumps and injectors. Old monster diesels can run on a 30 forever.
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Old 11-05-2013, 01:31   #30
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Without a fuel polishing system, the optimal primary filter is a turbine with water separator and 30 microns element. This takes care of all water and most crud. The fuel then passes through the engine mounted secondary filter, which is sized by the manufacturer to match what the engine needs and for modern diesels often 5-30 microns.

Let's say the secondary is 5 microns. If you have a 10 micron primary then the primary will always plug up before the secondary which means you can filter less fuel with that combination before needing a new element and trouble shooting. If you have a 30 micron filter, then t's much harder to say which one will plug up first, but from stories I still think the 30 micron filter first.

There is another thing: these filters are not perfect. A clean 30 micron element might catch most 10 micron particles untill the small passages clog up. The rate then goes down. There are good white papers about how they function and it helps to read and understand them.

When you have fuel polishing then a 2 micron element in the primary makes sense. I polish fuel at 10 microns.
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