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Old 13-05-2008, 07:46   #46
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Originally Posted by Extemporaneous View Post
A couple of things:
Is there a more proper term then "lean condition" for this? Or is that the right term? In a gas engine lean would have to do with the fuel / air mixture and that is not really what we are talking about.
If it is the right term then let me know, it just seams that it would be more properly described as a fuel starved condition, just like a plugged filter.
To say that a finer filter would clog quicker is a given, but once ANY and ALL filters clog it starves the engine of fuel. I think running a larger micron filter in front of a smaller micron filter should cut down on extensive filter changing and give better filtration, would it not?
Would not running filters, 10 micron then 2 micron or 30 micron then 10 micron in series provide both better filtration and minimize premature filter changes? Clearly this would depend on what you are trying to filter through it, but all things being equal.
It's not lean as compared to a gas engine. A diesel ingests the same amount of air with each stroke. As the filter is increasingly clogged the amount of fuel flowing diminishes. This allows less fuel to reach the engine and less fuel available to make power. Then finally it dies from fuel starvation. I have seen when the filters get clogged. Air leaks start to develop at clamps and fittings. These would normally be non existent with proper flow.
On a mechanically injected engine theres no need to filter finer than 5mcn. Anything smaller will pass. Most of the filters installed on engines are 5-7 mcn. This advice is useless if your retentive about fuel quality.

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Originally Posted by JiffyLube View Post
Was my assumption correct?
"I'm not very engine inclined, but I took it to mean that two small of a micron filter would restrict the required flow of fuel to the engine."
yes
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Old 13-05-2008, 08:38   #47
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Originally Posted by never monday View Post
On a mechanically injected engine theres no need to filter finer than 5mcn. Anything smaller will pass. Most of the filters installed on engines are 5-7 mcn. This advice is useless if your retentive about fuel quality.
Following this thread, here is what I get.

5 microns is OK and will burn.
Fine.
Over that and damage of some sort will begin.
Fine.
7 microns is bigger and falls into the "some sort of damage" category.
Maybe not so fine.
One of the most popular filters comes in 30, 10 and 2 microns.
Yikes! - 10 is twice 5 and definitely falls into the "some sort of damage" category.

So now, to my average mind and my average logic something is missing.
Either the engines work just fine with 10 micron filter (they are overbuilt or under rated for the "stupid" factor) or they do not.

There is an answer here somewhere.
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Old 13-05-2008, 08:43   #48
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the answer is your forgetting the engine manufacturer installed a filter on the engine when it was new. This filter is 5-7 mcn quality. Any filter upstream from it should be more coarse than 5-7 mcn. NOW, if someone removed the engine mounted filter from your engine, that's another story.
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Old 13-05-2008, 08:44   #49
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Cummins requires a 2 micron filter to stay within their warranty for a 2007 B Series turbo diesel. So that's what I have.
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Old 13-05-2008, 08:47   #50
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Cummins requires a 2 micron filter to stay within their warranty for a 2007 B Series turbo diesel. So that's what I have.
well that's not a mechanically injected engine, so it's not pertinent to the topic here, thanks anyway.
Following manufacturers guidelines when in warranty is the best answer to any question
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Old 13-05-2008, 08:49   #51
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the answer is your forgetting the engine manufacturer installed a filter on the engine when it was new. This filter is 5-7 mcn quality. Any filter upstream from it should be more coarse than 5-7 mcn. NOW, if someone removed the engine mounted filter from your engine, that's another story.
OK
That means a 10 racor and the one on the engine.
The one on the engine is not visible, IE glass covered, nor is there a gage on it. Any engine I have ever seen anyway.
So when it needs changing the engine stops.

My logic = if there is a 10 upstream then there is no way to tell how clogged the engine filter is until the motor starves for fuel.

How much notice does one get?
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Old 13-05-2008, 10:49   #52
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Fuel Filter Sizes....

It seems that if you have two filters the same size (microns) in series, you have, in effect, only one filter. The second filter in line won't filter anything, since trash is already caught in the first filter. When the first filter clogs, you have to change it. Unless, of course, you have a second filter in parallel.

Also, if you have (as an example) a 10 micron first and a 2 micron second, the second filter only has to deal with junk less than 10 microns, not all the junk coming down the fuel line. Seems it would therefore last longer than if the first filter was a 30 micron, or if there was no primary filter.
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Old 14-02-2009, 14:09   #53
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So here is what I'm doing (unless someone points out a problem).
What do you think?
It's been a long winter, so I haven't been on this the way I'd have liked to have been.
I have my filters but still need a wack of 3 way valves and a polishing pump.
Considering how many I need, does anyone have any suggestions where I could get them at a reasonable price? Also any suggestions for a polishing pump?
Thanks,
Extemp
Thought I'd post my final design. Same a before except that the fuel polishing pump can now also be a back up for my electric fuel pump on my engine.
I am in the final throws of putting it together and have a question.
Do I need back flow prevention on my fuel supply lines into the fuel filter system?
I'll post a picture of the final product when it is COMPLETE. Prorated against the time its taken so far, should be in a few months (only 99% complete right now).
Let me know about the back flow if you would.

Thanks,
Extemp.
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Old 14-02-2009, 15:22   #54
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Might be the last question (arrr, might not).
I am replacing the stock T-Handles with vacuum gauges. Can I install fittings and tubing and mount them remotely from the filters?
What type of tubing would I use? Something good for vacuum and diesel I'm sure. Anyone know of good brand and model/type?
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Old 14-02-2009, 18:20   #55
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I know first hand how this goes. Motoring along in 7' following seas with the tanks getting stirred up The rpm start to drop and the already to slow speed of the boat slows even more. The boat is really getting rocked now and I need to open the motor hatch and steer the boat and catch everything flying around the copit and turn the valve. Oh yea there is gear on top of the motor hatch. OK so now I change the filters at the first sign of junk in the sight glass. and I installed a polishing system as well and keep the motor hatch free of gear Overkill ? Maybe but peace of mind is well worth the price of a box of filters
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Old 14-02-2009, 18:33   #56
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The whole idea of a dual filter system like Racor's is so that you can quickly switch filters without having to shut down the engine to change filters while in the mean time introducing air into the system, therefore having to prime the system. A ten micron filter is fine for most older, non computerized Diesels.

Having filters in series from course to very fine only prolongs the amount of time before one of them clogs requiring you to shut down the engine to change it.
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Old 14-02-2009, 19:17   #57
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Lesson learned........ Have easy access to the fuel valve and run your fuel polisher when the water is rough and the tanks are getting sloshed around. Change the filters offten. I use the 1 micron racors and still get the tar in the secondary filters..
If the tar is the fuel breaking down Then when storing the boat for any length of time should we have the tanks empty as possible?
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Old 14-02-2009, 20:26   #58
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I would not do that

Just another number of connections to leak, hoses to chafe/degrade.

Plus don't you think the line would have to be filled with diesel?


Quote:
Originally Posted by Extemporaneous View Post
Might be the last question (arrr, might not).
I am replacing the stock T-Handles with vacuum gauges. Can I install fittings and tubing and mount them remotely from the filters?
What type of tubing would I use? Something good for vacuum and diesel I'm sure. Anyone know of good brand and model/type?
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Old 14-02-2009, 21:07   #59
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Just another number of connections to leak, hoses to chafe/degrade.
Plus don't you think the line would have to be filled with diesel?
It would be more connection for sure. You make a good point.
I was thinking of moving them off the filters to a viewing port (3 feet) that I would put into the engine room to pilot house bulkhead. They and the tubing would be above the filters and it is vacuum so should be empty.
Perhaps I'll give that more thought.

Thanks,
Extemp.
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Old 14-02-2009, 23:05   #60
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If the current location of your filters is not easily viewable and you have that much concern about the condition of the fuel in your tank(s) go ahead and do it.

Onboard the vessel that is my avatar, as well as another that I worked on...it was fairly easy to pop into the engine compartment/engine room and take a peek while on watch.

Probably the most difficult part of the install will be making some kind of holder for the gauges that will keep them secure from vibration.
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