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Discussion Starter #1
So much talk about filter micron size! Wondering what the OEM filter is. Some are excited about the new Racor coming out pre OEM at 10 micron. Thats problably about what the OEM is, so why not just change the OEM more frequently ? Some put in a filter ahead of the OEM thats 2 micron! So what good is the secondary OEM filter. anything getting thru primary is also going thru secondary! Seems to me a secondary filter at 2 micro would be the best! Or get Racor or someone else to make a 2 micron that fits the OEM canister! Then change frequently ! Anyway, if you could tell me what the OEM micron size is, I can think about all this! Thanks ! Dan
 

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I believe the the stock filter is 88% efficient at 2 m Edited by: hoot
 

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The OEM fuel filter results reported from 44% to 68% efficiency (or lack thereof) in the >2, micron size spectrum. i.e. allowing 2,278,570 particles >2 microns to pass through the high pressure fuel system with each gallon of fuel used.
As example, my diesel fuel throughput is 431,000 particles >2 microns.
The poor level of poor OEM fuel filter performance is what prompted all the work that has taken place to incorporate 98/99% >2 micron efficiency secondary filtration.
George Morrison
 

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hoot said:
I believe the the stock filter is 88% efficient at 2 m
Just to be clear... this number I quoted is per Racor.

Real world testing per Georgecls and others has shown it to be worse.
 

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We can clone sheep but not filter diesel fuel.
Im really having a hard time understanding this 2 mic thing.

Why not have a 3 stage kit.
Filter 1= water/asphaltine/25 mic's
Filter 2= 5 mic's
Filter 3= .5 mic's at 100% (pure fuel)
 

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A 2 micron filter will still pass some contaminants larger than 15 microns. Two filters are much better than one even if they have the same rating. --SS
 

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I am actually going to go to the 3 filter system with a lift pump. Fuel quality locally is as high as you can reasonably attain, but that is not true everywhere. I now have a 2 micron pre filter, but that is bassackwards, plus the 2 plugged up with a bad load of fuel.
 

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Georgecls, so what filter would you recommend as a pre? I also read how guys are having to prime everytime they want to start! Now way do I want to deal with that! I am also thinking about upgrading the fuel filtration system.


I have stated this before but no one replied....if the filter is flawed then why doesn't GM fix the problem....like installing the proper filter(s) for the job. This is clearly a problem! Just my two cents.
 

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Discussion Starter #9
George !!! What filter setup are you running to improve your filtering! Im still wondering what the Racor secondary setup at 10 micron will do for us. If all those particles > 2 micron are passing thru the 2 Micron OEM. wont they keep on truckin thru a 10 micron secondary filter? I plan to do something in the spring, but not sure what the best plan is! Thanks ! Dan
 

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Regarding OEM and why doesn't GM upgrade the filter. Excellent question which is answered by economics 101. As long as a manufacturer can make it through warranty fairly unscathed, happiness. Obviously there are some significant warranty fuel system issues with the Duramax fuel systems which is apparently moving the OEM towards a new 2 filter arrangement for follow-on production.
Single pass filtration presents a huge problem for an OEM in that ultra fine fuel filtration can create instantaneous, huge operational problems when a area of a country encounters sub-freezing temps for extended periods. Cellulose filters contain a significant amount of water which when exposed to below freezing temps, begins to expand, as water and only water does. The expansion of the molecules creates a restriction which further exacerbates cold weather issues as the fuel is already thickened with wax crystal formation, etc.
Additionally, when one achieves ultra fine 2 micron filtration with cellulose, filter dirt holding capacity and flow rate suffers as much of the filter ends up a solid; i.e. does not flow at all right out of the box..
In other words, ultra fine fuel filtration on a mass oem scale is one very difficult, challenging task..

I am using a 2 micron beta 2000 fully synthetic filter from my 1,000 gallon tank fuel dispenser which is protected by a 2 micron desiccant breather... Thus I have 14/11/10, 35 ppm water, BP Diesel Supreme (Cetane Index 50), water crystal clear diesel fuel going into my Duramax, 6.5TD, etc.
George Morrison
 

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And George said we can all stop by to top off our tanks with that clean + cetane fuel...

Its a long drive from Long Beach so I will sit this one out.
 

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Georgecls said:
I am using a 2 micron beta 2000 fully synthetic filter from my 1,000 gallon tank fuel dispenser which is protected by a 2 micron desiccant breather... Thus I have 14/11/10, 35 ppm water, BP Diesel Supreme (Cetane Index 50), water crystal clear diesel fuel going into my Duramax, 6.5TD, etc.
George Morrison

 

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Thank you for posting the Beta ratio and ISO references.
When one lives with these charts/numbers day in day out, one forgets that everyone doesn't deal with these day in day out.
George Morriosn
 

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OK....So for those of us without a degree in filtration, what is a good filtration system for those of us WITHOUT a 1000 gal super filtered tank??
 

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Based on many discussions with Racor, and after reading literature of other systems Vormax and Baldwin's fuel management system that use "coarse filters into fine", I went with a 10 micron primary, and a 5 micron secondary, nobody offers a 2 micron final for the 6.5 or I'd go with that for final myself.


Yes DMax is higher pressure operating system, but the filtration is before the injection pump and before pressure get jacked up to final pressure, so not a whole lot of difference from a 6.5 pre IP delivery system to the DMax.


I'm leary of 2 micron into another 2 micron filter, Racor says on their site and on my calls to their tech line say 2 microns for final filtration only, maybe that is just for their filter.


Their concern was that 2 micron raw/primary would grab too much stuff and impede flow to secondary filter for if a 2 mic primary catches everything 2 mic and up it could clog very quickly. Use a bigger filt as a primary 10-30 mic to remove bulk of trash and let 2 mic catch the smaller stuff was their recommendation.


A lot of discussion here and at TDP on this topic, you will have to do what you think best, I've seen the cutaways, looks to me like with 2 mic primary filt, the trapped dirt has been shifted from the on engine bowl to the pre lift pump bowl, but it's physical size is bigger so it can hold more dirt, and periodic changes should keep it from becoming an issue.


My concern here is what about when you are away from good known fuel supply, and you get a bad load of fuel, catching everything big and small in the 2 mic primary, and impede flow to the on engine filt.


From personal experience I had a filt plug up to the point of reducing top end performance while towing within 5K of it's last filt change, the resulting "fishbiting" was cured with a new filter, I suspect a bad load of fuel gotten on a 5000 mi road trip 2 mos prior; at new to me, fuel stations; even though all was bought at truck stops.


Can hi differential pressure across a blocked primary cause it to blow and become a source of blockage to the on engine filt, and then the 2 mic on engine also blows as it picks up normal junk in the fuel plus filter media from blocked primary.


I have seen similar consequence happen in a former life where I was a fuel farm manager for the ship I was serving on; I was responsible cleanliness of fuel to the ships engines, we carried 621,000 gal and could suck it up at 100gpm going all out. I also managed all the fuel for the onboard or visiting helos. Sometimes sailors did not always want to change primary filts at alarm, and would bypass it until alarm went away, then filts would blow causing injector pump fails and hot starts, when IP stuck in full flow mode jammed with trash.


Now this is apples & oranges, I know pressures and gpm delivery isn't the same, jet turbines vs Diesel, but at some level concept is the same, injectors are injectors, fuel is fuel we ran them on Marine Diesel very close cousin to #2 Diesel.


Please don't berate me these are my observations and my opinion; and this is a forum, a place to express opinions, I'm not trolling looking to stir dissent. If we were doing complete scientific testing to include accumulation over time, DP across filter over time, time blocked vs time to media fail, and I wanted to argue a data point then I'm being obstinate and need jumping on. Final cleanliness of sample is just 1 piece of a filter sizing puzzle/recommendation.


It is for the reasons and my experience above why I went with a 10 mic primary, which is more than factory set up but does not deviate from GM flow spec as a clean 10 mic flows easier than a clean 2 mic, and I've also installed a 7" vacuum switch at each filter to know when it needs changing not an arbitrary mileage or time installed date change recommendation, which will also alert me t
 

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Wow, had to take "2" coffee breaks reading this one...
When Georgecls mentioned GM fuel warrenty problems I had a question or two pop in my head. I know the DMax has the 100,000 mile warrenty, but what about the fuel system? I have 46,000 miles on my truck now and if my injectors go bad due to the fuel delivery system, will GM cover this or would this fall under the extended warrenty, that I did not purchase?
I have not had any problems so far and I surely hope I never do but it would be nice to know what warrenty coverage this would be under if anything was to happen. Also, what about the Allison, does that go with the motor at 100,000 miles? Thanks, Jeff
 
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