Next message: David Stahl: "Re: T&T: Fw: Upper Bay News"
Brian, as a high volume user of JD engines, I'm sure you're aware of JD's
position that anything more restrictive than a 30 micron primary filter is not
recommended. In fact, JD doesn't even appear to support Racors at all. When
my JD 6068 experienced fuel pressure problems, JD made the local JD service
technician by-pass the Racor to make sure that wasn't the problem.
In the past I was a supporter of 2 micron primaries and to just change the
secondary engine mounted filter annually. After all the Racor cartridges were
much expensive than the $35 Yanmar filters and a whole lot easier to change
in any condition. And a vacumn gauge and visual inspection will give me
forwarning of primary filter problems when there isn't an equivalent forwarning
for secondary filters.
Now I've reconsidered, but done so without factual evidence yet to support
my current thought process. I now use 10m primaries and am considering JD's
recommendation to use 30m primaries. My new thought process is based on my
assumption that the amount of trash in the 3 to 10 or even 3 to 30 micron range
is probably insignificant. If this assumption is true, the amount of sub 10
or 30 micron junk that gets by the 10 or 30 micron primary will not be so
much that the secondary filter will ever require changing more often than
recommended by the manufacturer. Obviously, well at least I think it's obvious,
that a 10 or 30 micron primary filter will not clog as soon as a 2 micron
primary filter.
Although I don't have engineering evidence to support my new thought process
I do have some practical experience. My new boat's first load of fuel was
bad. It would clog, or nearly clog, a 2 micron primary filter in less than 20
hours. So I changed to a 10 micron primary. Doing so doubled the amount of
time it took to clog the primary. After changing primaries 3 times (twice
they where 10 micron units) I changed the secondary 2 micron JD filter and it
appeared clean. I did have the tanks professionally cleaned at that point,
so I can't effectively do a similar test with 30 micron filters.
As someone else pointed out, this topic and the twin vs single engine topic
are like comparing dogs and cats. Well, maybe not, dogs are better pets than
cats--aren't they :-)
Gil
"Dog's Life"
OA Classico 50
Hi Gil
Yeah I think dogs are much better pets as I sit here in my office my 100lb
13 year old rotwelier lays under the desk he's been coming to work with me
every day for 13 years. But I can see the logic of a cat if my buddy was 5lbs he
would still be able to go cruising with the family at 100lbs he's gotten to
old to handle it. I can also see the logic on both sides of the twin vrs
single argument but I'm not seeing the logic in this argument. I have received an
awful lot of off line responses and almost everyone in the 10 micron camp
says the same thing "this is what the manufacturer recommends". But nobody
including the manufactures can tell them why. Now they do give some reasons like
flow rate and that's not accurate. They caution about exceeding the change
intervals on the secondary and that's not (or shouldn't be part of the 2 micron
philosophy). And then they go into a lot of gook about how a filter is not a
point of failure and how we are all to stupid to read vacuum gauges. I think
Frank's post best explains why they have this position.
The Idea of a 2 micron primary is not as new as some may think. It gained
popularity when Passagemaker magazine began talking about but the idea was
around before Passagemaker even existed. It came to my attention about 15 years
ago and we have used it on our boats for about that long. We primarily build
production boats so the first of any model has to be inspected and approved by
the engine manufacturer to insure warranty. Detroit, CAT, Cummins and John
Deere have all given us approval on 2 micron primaries the reason we get
approval is because it meets the spec they call for. The primary filter has to
have at least the minimum required flow rate and the element has to be of a
micron rating at or below the manufactures spec. So it can be lower or finer but
it cannot be higher or courser and the flow rate has to be adequate with the
element installed and there's more but nothing relevant to this discussion.
Now if you or I as a boat owner call the dealer and ask them about it we
will likely get the easy answer or company line "just do what we tell you or
something terrible will happen" and again just take a look at franks post I
think he explains why very well. As a builder we don't get treated that way. We
get one or more application engineers that come here and perform all there
tests look at all the drawings and make sure everything meets the spec. These
guy are usually quite willing to address a different idea and I have never had
any trouble with the 2 micron primary and never thought I would because it
meet the spec.
It has been suggested in some posts that you will void your warranty if you
use a 2 micron primary and that's just plain wrong. If you used a 30 when the
spec says 10 or you exceed the recommended change interval on the secondary
to the point where it deteriorated and contaminated the injection system then
sure you may very well have warranty problems. But if your flow rate is
within spec the 2 micron element will not effect your warranty at all.
In your situation I'm not sure going to a higher micron rating is a good
idea You primary is going to trap whatever it rated for anything finer will be
trapped in the secondary or pass thru the injection system. So a higher the
rating on the primary will cause more to be trapped in the secondary. If your
clogging the 2 micron primary I would increase filter area or pipe a second
filter in parallel.
I have gotten replies from some who say they would like to use the 2 micron
primary but it plugs up very quickly. I my view heres the bottom line there is
no free lunch if there's dirt in your fuel you want it to end up in the
filter. In the traditional system some of it is going to end up in the primary
and some will end up in the secondary. You can't choose what micron level of
crap is getting into or developing in your tank you can use a vacuum gauge but
you will only be getting half the picture you have no way of knowing the
condition of your secondary. You have allowed the crap to get closer to the
injection pump and only one element is keeping it from entering the injection
system. Even with good maintenance you still may end up in a situation where you
don't know which filter has caused you to shut down or you didn't get warned
before a shut down. You may end up having to change a secondary on a hot
engine and it is probably more difficult and definitely more critical than the
primary.
The 2 micron secondary solves all these problems if it's plugging up quickly
add filter area better to trap it there than in the secondary. The only
situation I can see that this might not work out well on would be some smaller
engines with diaphragm pumps. I have gotten some posts that suggest some cannot
tolerate much vacuum at all. That could be the design and arrangement of the
tanks and lines or a pump that is just very small with a very low flow rate.
In that case you may have no choice other than the traditional system
typically small diaphragm pumps will better tolerate pressure (on the secondary
side) than they will tolerate vacuum (on the primary side). That's enough of
this time to go cruising.
Brian Palmetto FL
_______________________________________________
http://lists.samurai.com/mailman/listinfo/trawlers-and-trawlering
To unsubscribe send email to
with the word
UNSUBSCRIBE and nothing else in the subject or body of the message.
Trawlers & Trawlering and T&T are trademarks of Water World
Productions. Unauthorized use is prohibited.
