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Duramax DIY Pre-OEM Fuel Filter

Discussion in 'Do It Yourself Articles - How To's & Product Revie' started by saratoga, May 3, 2008.

  1. saratoga

    saratoga Unpaid Help Staff Member Moderator

    May 3, 2008
    Lithia, FL
    This has been done on an 06 Dmax, but the concept is just as applicable to Fords and Dodges.

    Parts Needed:

    Filter Stuff:
    24770 NAPA filter head, 1"-14 thread, qty. 1

    3674 NAPA fuel filter, 2 micron, qty. 1

    801-8 Grey Parker Push-Lok hose, qty. 10'

    30182-8-8B Parker Push-Lok 1/2" NPT Male Adapter, qty. 2

    33482-8-8B Parker Push-Lok 1/2" Tube Adapter, qty. 2

    Brass Compression Elbows 1/2" (Lowe's), qty. 2

    4" X 12" steel plate and some black paint (Lowe's), qty. 1

    3/8"-20 X 4" bolts and locknuts, qty. 2

    1/4"-20 X 1.5" bolts and locknuts, qty. 3

    3/8" sheet rubber to use as an isolator behind steel mounting plate and frame

    On a CC, locate the two vertically spaced holes already in the DS frame rail just in front of the fuel cooler. Measure and drill holes in steel plate to match. Drill three holes in steel plate to mount the filter head. Paint and assemble. Use teflon tape and install the two 30182-8-8B male adapters into the filter head and tighten. Install the two plugs into the unused ports of the filter head with teflon tape.

    Remove the 1/2" steel fuel line from the spring clips holding it to the frame rail so that you have room to work. Using a mini tubing cutter, make an incision in the fuel line in between two of the mounting clips. Remove about a 4" section of fuel line. Warning: fuel will siphon out of the tank. Have a piece of rubber hose ready to slip over the tank end of the cut line to hold up higher than the level of the fuel tank.

    Mount the steel plate to the frame rail as shown using the 4" bolts and locknuts.

    Install the two brass compression elbows on the fuel line as shown and tighten. Install the two 33482-8-8B tube adapters into the brass elbows and tighten.

    Measure the lengths of hose needed and cut. Moisten the end of the hose in clean water to lubricate and install one end onto the barbed inlet port on the filter head. Install the other end to the adapter on the fuel line closest to the tank. Install the other length of hose to the barbed outlet port on the filter head and leave hanging into a bucket or container. Using compressed air and a rag, blow into the fuel filler neck to start the siphon of fuel through the filter (this keeps air to a minimum in the system). Once a stream of fuel is coming out, install the outlet hose onto the other barbed adapter on the fuel line.

    Start the engine and allow to idle until the engine dies. Bleed air from OEM filter under hood and re-start. Clean up and :cheers2:

    I'll post some more pics later on...


    Attached Files:

    Last edited: May 3, 2008
  2. Pepperidge

    Pepperidge Member Advocate Staff Member Lead Moderator

    Feb 10, 2008
    Slidell, La
    Damn Grady...whys the undercarriage so clean?

    I'm embarrassed...
  3. saratoga

    saratoga Unpaid Help Staff Member Moderator

    May 3, 2008
    Lithia, FL
    Thanks Pep.
    Call me the pavement queen :D
  4. 12ga diesel

    12ga diesel Jack of all, Master of none

    May 4, 2008
    Yeah, I think that is about the cleanest underside you'll find. Nice write up man. Thanks for putting in the detailed parts list as well. This is something I'd like to tackle.
  5. SEA04DMAX

    SEA04DMAX Recruit

    May 5, 2008
    Very nice.....I just did mine and looks pretty similar.
  6. J06EQ

    J06EQ Recruit

    May 9, 2008
    Nice. I need to do that to mine.
  7. BigBlueBurban

    BigBlueBurban Umm no...WAIT...yes

    May 7, 2008
    Grand Rapids, Michigan

    Note to mods- I can't reply with just x2 - need at least 5 characters. Can that be changed?
  8. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    You know I've wondered why many in DMAX land jumped on the Nicktane et als, 2 micron filter as prefilter, does not make sense to me, filters that small are meant to be used for final filtration, the premise that a bigger filter won't have to be changed as often is correct, because the filter body is physically larger it will hold more trash than the stock 2 micron filter will.

    But using it to stop all particles IMO puts engine at risk, hear me out I'll share some been there done that with you while not apples to apples comparison does need to be thunk on.

    Once a filter gets full depending on it's design it either bypasses, or the filter media will succumb to hydraulic force applied to it and a "hole will be created in the media" either with a bypass or "hole" you are either sending unfiltered fuel or media toward your engine, or the small on engine filter, if using a filter without a bypass, until vacuum or flow is sufficient to "hole" the filter you are starving the IP in us 6.5ers case, or CR pump in DMAX case of fuel flow.

    Here is the experience part, back in days of me working as field rep at GE & USN we used to have a filter coalescer prior to our engines, in it was a water sep element, (10) 40 micron filters and about 100 gal of fuel, to filter last fuel going to our propulsion & power generation turbine generator sets. Invariably just before watch turnover we would get a high DP alarm on fiter towers which requires fuel drain, remove old elements, "mop out" of body, install new filts, refill tower, takes about 2 hrs to do it, so guys would be slick pull power fuse reset the alarm, and could get away with this until next major speed change where flow would cause the alarm. Nobody wanted to mess with it just before going off watch and crawling into bed with Diesel fuel all over them.

    Some times the alarm would "fix itself" and never come back, or so they thought, what was happening was filters were blowing, full flowing filts don't set off alarms, and we were starting to fail our jets fuel controls (IP's basically) during investigation what was being found was cellulose fiber in fuel controls, was a real problem for a while until we figured out what was happening, turns out this habit wasn't unique to a few ship but many, and 1st thing done at reciept of fuel control was to disassemble & clean before testing but no problems were seen on test.

    Cellulose wasn't found until we mandated test in as recieved condition, back tracked to operating habits of ships, so I'm wondering how many early injector fails in DMAX corrected by adding larger body 2 micron filter were due to media being sucked out of the tiny filter provided by GM engineers, rite concept filter as fine as possible to protect a 20,000 psi system, wrong IMO to try to do it with a small 2 micron filter as the ONLY filter in the system.

    Racor "improved" it's web site so I now no longer can find their text that said 2 micron filters are for FINAL filtration only, a 10 micron filter can be used as a final if fuel is known to be of good quality, or used for primary if willing to do filter changes often, and 30-20 micron filters are recommended for primary fuel filtration.

    Baldwin site used to have similar comments as well, to confirm it I called the tech lines for both Baldwin & Racor, ultimate is tiered system 30 mic, to 10 mic. to 2 mic, but how much "real estate" do we have for best filtration.

    As a 6.5er our on engine is a 5 mic nominal, so for mine I put on a 10 mic Racor primary before the lift pump & vac switches on both to know when my fiters are dirty, what I'm finding is I have yet needed to change on engine due to blockage, have pulled it a couple of times diagnosing a plugged in tank 70 micron sock, but never had bad on engine filter since installing the 10 mic primary fiter.

    By using the 2 mic as all in one it will plug quickly, putting in a large body 10 mic primary you are sifting "chunks" that will quickly plug a 2 micron, 2 micron as primary into a 2 micron final is doing what, mite as well just pull the final and remove the flow restriction and run solo large body 2 micron. Or run a large 10 mic so all on engine is dealing with is anything less than 10 micron, and there really isn't that much <10 mic stuff in fuel.

    IMO if you put on a 10 micron primary as large as the nicktane cat filter, or Napa filter shown in earlier pics, I'll surmise a OEM 2 mic would almost never need to ber changed.

    Add in a vac switch or DP gauge (which GM should have added) and carry spares of each, and you will never have a fuel contamination issue, and your fuel filter cost will go down as well since you will change fuel filts when they need to be changed vs when you think they should be changed, make sure your primary is water block treated and water will never be an issue either.

    By instrumenting with gauge or vac switch you will also know if getting a problem on highway from "strange'" supplier, that may be a hi-volume supplier that "just stirred the tank" from fresh fuel fill getting crud on nearly empty tank mixed up to the flow, it happens, I lost power on mine once could not move my 5600# g/n trailer more than 40 mph without bucking. A buddy suggested bad fuel filter, no way, I just changed it less than 5k miles previously it's new plus truck runs like raped ape not pulling the trailer; shore nuff changed the filter it was partially blocked, that was what led me to putting on 10 mic prefilter and vac switches to know I have a bad filt.

    Also note in the pics my primary is a 60T Racor set to feed up to 60 gph, most folks run a 45 gph racor on their 6.5 now factory lift for the 6.5 is 28gph max, so by sizing 2x flow I could ever put thru a GM lift, I've upped the dirt carry ability and not added any or much flow restriction to system, plus will handle flow of a after market lift pump ie Walbro FRB-5 10 psi 45gph pump.

    It mite be interesting science experiment for you DMAX guys to run a 10 mic primary to 2 micron OEM to see what interval/fuel quality you wind up with, I have no complaints at all with that set up on my 6.5 going to a OEM 5 mic nominal final.

    Attached Files:

    Last edited: Jul 24, 2008
  9. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    When mine was a was a 2 y/o "toddler" it was almost that clean underneath, I bought it in 2000 only 36k on the clock "little old man" owned it before me, Katrina saltwater submergings and Alabama/Mississippi "off road" adventures have changed it up some since then.
  10. dmaxfireman

    dmaxfireman 'Can Do' kindof Guy

    Jul 21, 2008
    Southwest CT
    Damn ex cab and crew cabs guys have so much room! I just picked up 220 gals of b100 and finally put on my pre-filter. took a little thinking outside the box but it squeezed in. pretty well.

    now to find a good toolbox tank combo for the bed that doesnt cpst an arm and a leg!
  11. saratoga

    saratoga Unpaid Help Staff Member Moderator

    May 3, 2008
    Lithia, FL
    I've changed the filter once since I put it on in Nov of 2006. It was cut open and the usual black gunk was only 1/4 the way up from the bottom (3/4 of it was still white).

    The way I see it (and my thought process may be completely wrong) is that yes, this is a 2u being used as a primary filter and normal logic stands to reason that a fuel filter setup should be installed in progressively finer steps, probably ending with the 2u.

    This is my viewpoint and only my interpretation to justify the 2u filter where it is.

    The filter I installed is a. huge (intended for industrial applications) and b. rated for 12-15GPM according to the WIX datasheet. My truck is bone stock tuning wise and the highest flow I've ever seen at WOT is 18 GPH or 0.3 GPM- far, far, far from what that filter is supposedly rated to handle. By my thinking and from what I've seen, the filter will slowly fill with gunk from the bottom up, and yes it will probably catch everything that comes out of the tank, catching far more gunk than the OEM filter wihich is still in place. But since the fuel flow is so small compared to what the filter is rated at, the chances are slim that it will clog unless I happen to pick up a tank of contaminated fuel.

    My .02 and change.
  12. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    Okay saw this post again yesterday and after sharing my USN experiences here http://www.dieseltowingresource.com/showthread.php?t=764
    it bugged me I might not have it correct; so I posed the following
    question to several filter manufacturers technical deptartments
    at Baldwin, Wix, Racor:

    I would like to know the opinion of your technical department about using a
    2 micron filter as a primary fuel filter, pre lift pump, a number of guys
    in a GM Diesel forum have concluded that a larger body 2 micron filter is
    better than a single small body filter supplied by GM on their Dmax
    engines, I think right logic but incorrect filter, as I do not see benefit
    of 2 micron into another 2 micron filter.

    I think it would be far better to have a 10 or 20 micron filter as the
    primary, let it do the "dirty work" and sift the largest particulate, as
    lions share would be 10 micron or larger in Diesel fuel tanks at truck
    stops. My fear that using a 2 micron as the primary, one runs the risk of
    it plugging the media, it blowing a hole from high DP restriction and you
    wind up with fiter media and dirty fuel after that happens.

    What are your thoughts?

    Their replies:

    you are correct, a 2 micron will plug to fast as the primary filter, the
    oem filter on there is a dual 2 micron element anyway, there is a 10 micron
    filter kit for the d max.(See attached file: 32319 Rev B (DMAX Filter Kit
    Mike Noldin
    Technical Service Specialist
    Racor Division
    Parker Hannifin Corporation

    Thank you for your internet inquiry.

    You are correct. If you use a 2 micron filter as the primary, the filter will plug up quicker than normal because the media pores are spun tight. A 2 micron filter will trap the very fine particles. To use a 10 or 20 micron as the primary filter, the media pores are more open, trapping large containment and whatever gets through the media would get trapped by the 2 micron secondary filter.

    Example: Chain link fence with chicken wire behind it. Throw dirt clogs against the fence, it will block the large clogs but the wire behind will trap the dirt that gets through after the fence breaks up the clogs.

    Bobby Ratliff/WIX/Affinia

    You are correct. Using a two micron filter as a primary filter defeats the purpose of having a primary and secondary filter in series. The primary filter should not be as efficient as the secondary filter. Using a primary filter that has an absolute micron rating between 10 and 20 microns in series with a secondary filter that has a nominal rating of 2 micron (5 micron absolute) will provide the best service life without sacrificing the filtration efficiency provided by the secondary filter. If you have further questions, please feel free to contact us.





    800-822-5394 EXT.79763
    Last edited: Aug 6, 2008
  13. Dura-Ration

    Dura-Ration No Obuma

    May 13, 2008

    I agree with with you Tim . But the cost of the OEM filter is about 30.00 dollars. Compared to the Pre-OEM 2 micron Filter 8.00 Dollars. I would much rather change an 8.00 filter than a 30.00 filter. My 02cents.
  14. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    Nothing wrong with a prefilter, IMO and filter mfrs recommendations is that a $8, 10 or 20 micron prefilter is the better option, there really isn't that much 2 micron junk in fuel, majority of stuff in fuel is "big", if I was running a 2 micron filter as primary which I can't do in good conciousness, it would have to have some sort of indication to tell me when it was plugged up.

    I'm going on 3 years with my 10 micron Racor primary maybe 50K or better on it, I have vac switches on the 5 micron pre IP and the 10 micron pre lift, had considered a 2 micron pre IP but 6.5s fuel system is only 2200 psi, vs 20k on the CP3s common rail set ups.

    I think and filter mfrs as per above comments agree 2 mic into a 2 mic is overkill, let a inexpensive 10 micron do your "heavy filtering" and not run risk of blowing the filter, your 2 mic on engine filt will last just as long with a large body 10 mic prefilter as with a 2 mic prefilter maybe even longer, plus finer the media the more restrictive the flow, are you power limiting because of too fine a media. There is a balance you need to make sure you aren't filtering too much too soon.
  15. Pepperidge

    Pepperidge Member Advocate Staff Member Lead Moderator

    Feb 10, 2008
    Slidell, La
    while I agree with everything you've said...exactly how much restriction could be inhibited in a 15gpm (not hour) media...

    I'll probably add a 10 micron before the nictane and a lift pump and if you'd like to help...I'd also like to put that vacuum warning switch we were talking about...but with some sort of led indicator instead of a gauge if that can be done...
  16. stacks04

    stacks04 McLovin

    May 9, 2008
    terryville ct
    i agree in theory turbine, but how much more inexpensive is a 10 micron v an 2. for 9 bucks through napa and the flow characteristics of the filter itself i am okay with it. i use it and currently have almost a year on my second one. and if it wasn't for getting my gm ones for free i'd still have the same one of those there also. but i did change it before plowing season last fall. also i run 3100 us pulse times on my biggest tune and with out a lift pump i hold 18500, 19000 lbs of rail pressure, through both filters. that is proof positive enough for me.
  17. RayMich

    RayMich Active Member

    May 9, 2008
    Mid Michigan
    Excellent posts, Tim.

    I totally agree with you. I have always thought that installing a 2 micron pre-OEM filter was not the right solution. Putting a 2 micron ahead of a 2 micron filter doesn't make much sense to me.

    However, I was under the impression that the OEM Duramax filter was a 10 micron filter, so having a 2 micron filter going into a 10 micron filter never made much sense to me, other than the fact that most aftermarket filters are a lot cheaper than the OEM AC/Delco filters and generally are much easier to replace. This is why I was considering adding a POST OEM 2 micro filter instead.

    Also, I was told that ALL OEM replacement filters for the Duramax are made by RACOR, so I've been buying WIX OEM replacement fuel filters from FleetFilter.

    I just checked the specs for the WIX OEM replacement filter for the Duramax at their website and they say it has a "Nominal 4 Micron" rating. See HERE. Is WIX being too conservative with their rating or is it a different filter than the AC/Delco filter?

    Does the AC/Delco Duramax fuel filter really have a 2 Micron rating? Is it no longer being made by RACOR?

    I like your idea of using vacuum switches to tell you when to replace the filters. I've never understood why GM doesn't use some type of sensor or sight glass to check the condition of the fuel filter. (The old 5.7L diesel engines used a Stanadyne filter with a glass housing, so you could tell if there was any water or if it needed replacement.)

    What vacuum settings are you using on the switches for each filter and where did you buy the switches? are the switches adjustable? Are you using a gauge with the switches or a light?

  18. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    I don't have a Dmax so I was only parroting what I had seen before that the Dmax had a 2 micron on engine, if it isn't 2 micron then yes indeed 2 micron into a bigger filter makes about as much sense as a 2 into a 2, (makes no sense), the 6.5s have a 5 micron nominal so I guess from what you guys are saying filters are about on par with what is on the Dmax, Stanadyne makes the filter for most of the 6.5 retailers, so possibly same for Dmax, there is 1 filter for 6.5 that isn't Stanadyne made.

    As far as micron rating goes, not 1st time I've seen Wix & others in error, IIRC they used to list the 6.5s filter as a 10 micron on engine, but when I contacted Stanadyne they confirmed that the filter they make (which all but 1 sell under their brand; Dipaco IIRC makes it's own filter) for the 6.5 are 5 micron nominal filters.

    For my switches any Racor dealer should be able to get them, pn RK20163 fixed setting for 7" Hg, I have them set to turn on a 12v red LED from radio shack, that I have mounted on my gauge pilar post, I guess any vac switch could work, say from McMaster Carr or grainger, but the Racor switch was plug & play and small enough to be out of the way installed.

    As far as cost of filters a Napa 10 micron should cost same or maybe even less than the 2 micron since filter media is not as fine I did a quick search 1 site selling 2 micron 3674 Napa for 12.87, and for same price 10 micron filter it appears to be same body/thread it appears to be a Napa pn 3374 http://www.globalfleetfiltration.com/catalog275734.html possibly found elswhere for less $$$ but that was 1st hit on search engine that gave basic info.
    Last edited: Aug 12, 2008
  19. Pepperidge

    Pepperidge Member Advocate Staff Member Lead Moderator

    Feb 10, 2008
    Slidell, La
    they both are rated to flow 12-15 gpm...I thought the finer filter media produced more restriction from the get go...could it be the larger size of the filter nullifies this effect?
  20. Turbine Doc

    Turbine Doc Just Another Diesel Guy

    Larger size filter nullifies the flow at 1st, but as it gets dirty the 2 micron will lose it's flow capability faster, in extremis, a wholly plugged 2 micron may blow completely and you would never know it and not only would you have dirty free flowing fuel but also filter media from the "holed" filter, since majority of stuff in fuel isn't very small let the on engine filter deal with the smallest of what may be in fuel rather than deal with everything large and small.

    I read back in early days of Nictane over on other site of injector fails with factory filt only, and adding 2 mic filter "fixed'" this to some degree, I would surmise from my USN experiences & plugged fuel filters feeding our turbines the larger body 2 mic filt does have a larger dirty carry capability for a while and so long as you get relatively clean fuel to begin with.

    But bad fuel can be gotten at any time so what happens to a 2 mic filt that was flowing but now isn't flowing so well, if filter is equipped with bypass circuit it bypasses, if it holds together all fuel stops and engine dies, but what if there is a bad pleat in the filter, or weak glue joint then the high DP over the media migth let go and you'd never know it until over time your injectors got gunked up, in a 20K psia system any solid even "soft" filter media works like an extrude hone cutting lance. Just theory on my part at to why some failed; probably not enough occurances for GM to collect data to study on it much, or they knew of weakness of system but didn't care figured if more survived to warranty expiration than failed they would be money ahead over trying to fix it.

    Sort of us 6.5 guys with bad IP fuel drivers, special extended policy for that 1 item to deal with when & if the issue happens, rather than a recall campaign to fix them all.

    Only way to know how long a large body 2 micron filter lasts with commonly available fuel is to run an endurance test, or you could defer to the testing filter manufacturers have already done, with results that say 2 micron filters are for final fuel filtration of fuel from a known good source; and that a 20 or 30 micron fuel is recommended as a primary for unknown fuel.

    Since I don't have on vehicle real estate for a 22/30 mic to 10 to 2/5 mic final I opted for 10 mic as primary for a compromise, plus I don't know if currently there is a inexpensive lift pump capable of pulling/pushing fuel across 3 filter elements adequatelty to keep my IP supplied with high volume fuel, I have a Walbro pump capable of 45 gph & 8-11 psi for my setup http://apeusa.com/?frpumps which is 3x over the GM 6 psi 15 gph lift pump, another key feature of this pump it is self priming, & it will flow on fail so my IP can pull fuel through it, albiet at reduced power maybe, but I can continue to drive, another LED I have not mentioned earlier is green power on LED so I know my lift is getting power.
    Last edited: Aug 13, 2008

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