Primary Diesel Filter/Water Separator Recommendation

[ErikFinn]

I would like to replace my old CAV unit with a new one, and I'm thinking to get a Racor one possibly. Emailed the "#1 Distributor for Racor Products" for recommendation but got no reply. So I thought to ask the fellow cruisers here at CF.
My engine is a 1989 Perkins Prima M50 50HP diesel with about 6000hrs, a 170 liter main tank and a 140 liter aux tank.
I like the dual assembly setups but they appear to be about four times more expensive than a comparable single unit.
I would like to know which model you guys would recommend for me to be the best price/quality unit bearing in mind the engine I have and the following factors:

1) the engine and the tanks are now 24 years old. (not sure whats at the bottom of the tanks... )
2) I sail in Asia, and the fuel over here is not always to western standards.

So bearing this in mind would I make a mistake trying to save money if I went for the single unit only? Or would it be more than adequate for me?

Also Racor seems to sell the same units but with different model names; is the only difference just the filter it initially comes with, I could change the filter later to any micron later if I wanted to? Everything else is identical? eg.
Racor 75500MAX30

Racor 75500MAX10

Racor 75500MAX2



Lastly, what micron size filter would you recommend for me?


Thanks,
Erik

[ranger58sb]

If you haven't found him yet, I think there's a Parker/Racor guy on here somewhere, and a search might turn him up...

-Chris

[jeremiason]

When Catalina built our boat, they placed a Racor 500 on each of my three fuel tanks. This setup allowed me to switch from one tank to another if the filter fouled and keep going.

I think the best possible setup is two Racors, again to allow you to switch from one to the other in the event of fouling, without having to change filters underway.

Most of the cruisers I met, including myself use 2 Micron filters in their Racors.

The ultimate filtering system, in my opinion is the Filter Boss, but it is expensive. In your case with questionable fuel, it would allow you to polish it at the dock.

[skipmac]

Originally Posted by jeremiason

When Catalina built our boat, they placed a Racor 500 on each of my three fuel tanks. This setup allowed me to switch from one tank to another if the filter fouled and keep going.

I think the best possible setup is two Racors, again to allow you to switch from one to the other in the event of fouling, without having to change filters underway.

Most of the cruisers I met, including myself use 2 Micron filters in their Racors.

The ultimate filtering system, in my opinion is the Filter Boss, but it is expensive. In your case with questionable fuel, it would allow you to polish it at the dock.

The Filterboss system looks very impressive but with a price tag to match. Might add that to my list of goodies to buy when I find that winning lottery ticket.

I went with a standard dual Racor 75500 to feed my 58 HP Westerbeke. That is still a lot more money than two single Racor 500 filters but includes a quick change valve to go from one filter to the other in case of a clog and also a vacuum gauge so you can monitor the state of the filter that is in use and see if it is starting to clog.

The question of what micron filter seems to generate a bit of controversy (like anchors, guns and mono vs multis it seems). One group says use a larger micron in the first stage of filtering and a smaller micron in the secondary filter, typically mounted on the engine. Common recommendation are 30 micron in the first stage and 2, 5 or so in the second. This prolongs the life of the first stage filter, makes blockages less likely but still protects the injectors and pump by the fine filtration on the secondary.

The other group says it's better to maximize filtration in the whole system and gives better protect the engine and filters aren't that expensive compared to engine repairs. I think if you follow this route you have to pay a bit more attention to fuel quality, keep clean tanks, follow a program of fuel polishing, etc or you might end up replacing the filters pretty often.

If I had the budget and was boating in an area with questionable fuel I would seriously consider the Filter Boss. If budget is a concern you can put together your own system for less money would accomplish the same things as the Filter Boss.

[noelex 77]

Originally Posted by jeremiason

The ultimate filtering system, in my opinion is the Filter Boss, but it is expensive. In your case with questionable fuel, it would allow you to polish it at the dock.

You can make a similar system for yourself for much less money.
It is only simple valves and pumps which can be easily purchased.

If you have the space consider larger filters. The Raycor 900 series has a much greater solids capacity. Filters clog very quickly if you develop a bug problem and even an immediate switch over is not ideal if your run time is only a 5-10 minutes, on the new filter, which I have seen happen on the 500 series.

[Group9]

Pick the model that fits your engine, but Racor, Racor, Racor.

And, put an electric fuel pump in and you won't ever have to worry about bleeding your engine.

[Badsanta]

Racor 10 micron for secondary and 2 micron for primary. Imho

[colemj]

The most harmful (and common) particulate size in fuel is 20 microns. Particles smaller than 10micron are much less common, and much more acceptable to the engine. Although it sounds like the correct thing to do, using a 2micron primary filter will simply have you changing filters more often (at potentially inconvenient times) for no practical reason at all.

Most engine mounted secondary filters are 5-10 micron, so the engine manufacturer is not concerned with particle sizes smaller than this. Some engines have 2 micron. It is difficult to get the companies to tell you what size they use.

Racor specifically recommends NOT using 2micron as a primary filter and recommends a 10micron primary for a 2micron secondary. Some diesel manufacturers will void their warranty if 2micron primaries are used.

Here is an interesting paper for you: http://www.seaskills.com/files/SeaSk...WhitePaper.pdf

We use a 10micron filter on the primary. If you often take on questionable fuel, a 2micron filter does nothing for you other than clog quickly. "Dirty" fuel particles are much larger and you are interested in simply gross cleaning the fuel (after removing visible particles and water with an intake filter, of course). In this case, I would buy a larger filter unit (Racor 900 or 1000) and use 30 or 10 micron filters. Alternately, you may be able to buy two Racor 500 for the same price and hook them up with a switching valve. I would still use 30 or 10 micron filters in these.

Keep in mind that filtration ability follows a distribution of particles. The nominal micron rating is for the top of that distribution. For example, a 10micron filter will filter ~95% of 10micron and larger particles, but will also filter a good portion of particles smaller than 10 micron. Your 2-10 micron secondary filter will take care of the rest.

Mark

[Badsanta]

To be clear, the small filter attached to the engine is the primary filter, the hopefully larger inline filter is the secondary filter.

[model 10]

Originally Posted by Badsanta

To be clear, the small filter attached to the engine is the primary filter, the hopefully larger inline filter is the secondary filter.

And to that note, there is a nice spin-on conversion kit for the sandwich CAV unit in the engine. It also eleminates bleeding the inj system after a filter change.

[colemj]

Originally Posted by Badsanta

To be clear, the small filter attached to the engine is the primary filter, the hopefully larger inline filter is the secondary filter.

No, it is the other way around. The filter attached to the engine is the secondary or final filter and the larger unattached filter is the primary.

Mark

[skipmac]

Originally Posted by colemj

No, it is the other way around. The filter attached to the engine is the secondary or final filter and the larger unattached filter is the primary.

Mark

Well I could be wrong but that's the way I always understood the terms.

Primary - first in line, does the initial IE first or primary filtering.

Secondary - second in line, does the second stage of filtering.

[skipmac]

Here is a quote from a truck and auto supply company. Had not thought about the issue of the primary being on the suction side of the fuel pump. Makes me more inclined to keep the primary filter in the 30 micron range to avoid putting too much suction on the fuel lines which would bring a higher risk of getting air in the lines.


The primary fuel filter must offer low restriction because it is mounted on the suction side of the fuel pump where normally a suction pressure of only 5-6 pounds per square inch is available. This filter has the job of protecting the transfer pump and lightening the load of the secondary fuel filter (if installed). Primary fuel filters typically have a nominal rating of 10 - 30 microns.

Secondary fuel filters are mounted between the transfer pump and the injectors. The secondary fuel filter is designed to offer full protection to the fuel injectors. Since these filters are mounted after the transfer pump they tend to see much higher pressures than primary filters. Secondary fuel filters typically have a nominal rating of 2 - 10 microns.

[model 10]

Originally Posted by skipmac

Well I could be wrong but that's the way I always understood the terms.

Primary - first in line, does the initial IE first or primary filtering.

Secondary - second in line, does the second stage of filtering.

I would vote for the filter on the engine to be the primary filter. If this were in a taxi cab the filter on the engine would probably be the only filter, ie the primary.

[delmarrey]

Originally Posted by Badsanta

Racor 10 micron for secondary and 2 micron for primary. Imho

Why would you put a fine filter in front of a course filter. That's like putting a coffee filter in front of a spaghetti strainer.

If you look at boat/motor manuals the primary filter is the first from the tanks.