Fuel Filter Test Results

**Merle** · 10-31-2002, 09:31

What is the best filter on the market for the Duramax?

**chuntag95** · 10-31-2002, 10:04

The best filter or filters is still to be determined.

To answer the question on why put a fine filter after the OEM filter, think about it like this. A filter is a bucket with a screen on the bottom. It has a limit to how much it can hold and it holds only the particles that are larger than the holes in the screen. If you put sand through the bucket with a large screen, you catch the big stuff. If you run it throught a med screen you catch the med and big stuff. If you run it through a fine screen, you catch all sizes. Now, if you put them in series or one after the other, and put the fine screen first, what good with the others do? You will just have to empty the fine screen bucket more often. Now, if you use the big followed by the med and finally the small, each bucket will catch different sizes and you will spread out the amount of debris between the filters and they will last longer because they won't fill up as fast. Each bucket can only hold so much. Staged filtering is a common practice in industry.

The whole question here is what size screen is on our bucket? Over simplified I know, but it illustrates the point. JK is right, rushing in could make it worse. The right media in the right size filter in the right location is what is needed and only careful planning and testing will get us there.

**george morrison** · 10-31-2002, 15:31

We have Tom's re-run from his post filter tomorrow am, Friday. John Kennedy's should be completed by Monday.
By Mid-week we will have 3 complete sets of before the fuel filter and after the fuel filter analysis results which will a good sampling of data on the efficiency of our OEM Duramax fuel filter..
George Morrison, STLE CLS

**george morrison** · 10-31-2002, 17:27

Tom's fuel before and after fuel analysis results are complete. Tom sampled his local Galisto, NM source and the capsule results are:
Cetane Index: 47.31 (very good!)
Water 45 ppm (good)
ISO Cleanliness: 18/16/12 (Target 15/13/10)
Particles per gallon equivalent:
>2 Microns: 8,353,495 particles per gallon
>5 Microns: 1,873,575 particles per gallon
>15 Microns: 147,615 particles per gallon

Target:
>2 Microns: 1,211,200 particles
>5 Microns: 302,800 particles
>15 Microns: 37,850 particles

The AFTER filtration analysis reflected the following.
Water: 51 ppm (HIGHER than pump of 45 ppm!)
ISO Cleanliness: 16/15/12 (Target: 15/13/10)
Particles per gallon:
>2 Microns: 1,585,915 particles per gallon
>5 Microns: 651,020 particles per gallon
>15 Microns: 136,260 particles per gallon

Filter efficiency:
>2 Microns = 81% reduction
>5 Microns = 65% reduction (most critical size)
>15 Microns= 8% reduction

So for the most critical particle size our OEM filter is slightly more than 50% efficient and not near the 92% efficiency level for the CAT filter or the Racor "S" on Greg's 6.5TD.

Additional note: Tom's previous "after the filter" sample came back reflecting an ISO of 19/18/15, actually worse than his pump fuel sample. He either had a defective fuel filter, a mis-install, or rupture. The first test filter had a little over 8,000 miles on it. The second filter test was for a filter installed Friday and driven over the weekend with less than 200 miles on it.
More results next week.
George Morrison, STLE CLS

[ 10-31-2002: Message edited by: george morrison ]</p>

**TDIwyse** · 11-01-2002, 07:05

Very interesting. George, do you know what the margine of error is for these tests? I'm not referring to the possible human error involved in the sampling of the fuel, but the actual measurement of the particles?

From the few tests I've seen here it makes wonder about a few things. The first is there have been at least one area with both filter tests where the post-filtered fuel was worse than the pre-filtered fuel (IIRC previous test had worse particles, this one has worse water). I don't understand how a filter could be adding contaminates? Perhaps since this last filter is so new, it could have had water in the filter media from the manufacturering process and is slowly releasing it? Is it possible that there might also be some particle contaminates left from the initial manufacturing process?

Also, how is it that a filter can be more effective at filtering smaller particles and less good at filtering larger particles? I don't understand how if there are gaps big enough to let a larger particle flow through how it could then trap a smaller particle.

I'm going to go back and re-read how the samples are being captured. This is very interesting stuff.

**george morrison** · 11-01-2002, 07:29

The margin of error for the particle counting is very small. The most probably cause for variations is sampling technique. The problem (only one to my knowledge) of the 'after filter' indicating higher particle counts than the before was for a fuel filter with 8,000 miles on it. The most likely cause of the higher particle count would be filter failure, defective filter, improper installation (not so difficult with the Duramax installation!),etc. as opposed to the ISO 9002 lab variation. In other words, from my professional experience, the particle counts, overall results is the one aspect we can count on; good sampling technique is sometimes very difficult to accomplish. That said, I have much confidence in the sampling techniques used in the high PC case so I am most suspect that it was a filter causing the reading.
Also, the sample point for the 'after filter' was the return line to the fuel tank. This then is after the fuel has made its complete trip through the filter, pump, injector circuit, and injectors. Thus, if we have a component producing wear particles, a failing component, carbon, etc. anywhere along the route, our particle count for this sample would reveal that debris also. This may be the source for the large particles and may well increase the particle counts.
We have additional 'before & after' samples that should be completed next week which are using a different sample point for the 'after', that being immediately after the filter, pump, but before the injector circuit. However, in this case the engine will not be running, eliminating the fuel system dynamics which can greatly affect fuel filter performance; i.e. the opening and closing of the injectors creates harmonics which back feed to the filter and can cause a cleansing action in the filter medium. In other words, a filter that may be labatory rated a 2 micron 98% efficient may test at 2 micron 65% efficient in real world operation on the engine.
This is a developing, on-going project and as more data comes available we will obviously be better able to make decisions..
George Morrison, STLE CLS

[ 11-01-2002: Message edited by: george morrison ]</p>

**TDIwyse** · 11-01-2002, 07:49

Thanks George, that info was very helpful!

**Catalina455** · 11-01-2002, 12:58

George, thanks for the information. I have taken your posts and forwarded them to my GMC service manager and talked with him. He said that there weren't any current cases that had reached GM's review (legal, which is the step before a TSB is published)but indeed there may be analysis being done at the R&D level. He informed his two senior Techs of the concern and ongoing user testing and they will bring it up at the zone service conference being held here in the DFW area next week. This forum will help to start the TSB analysis process. Although he hadn't seen significant cases of injector failure on the D-max, he fully expects it to be a significant warranty issue with the Racor and current PSI. He agrees from past experience with the 6.5 that the current filter probably doesn't meet the needs of the D-max and awaits more analysis so that a supplemental filtering solution can be found. Any information that you could provide will be forwarded to GM for action. He also promised to forward me with any action within GM that he can find as it enters the service channels. This dealer is in the top 5 nationally for sales/service of GMC, so GM will listen. You can contact me offline if you would like, otherwise I will continue to monitor the analysis and update the dealer. By the way, I am not empoloyed by the dealer. Although new to GMC's and diesels, my affiliation with the dealer results from the various Pontiacs I have purchased there over the years. I am active in Pontiac clubs and we work together to put on local and national Pontiac shows. Gotta go, time to see if I can line up the 2004 GTO for a show after it's introduction at the LA/Chicago Auto shows in January.

Regards,
Randy Allen

**george morrison** · 11-01-2002, 13:40

Randy, if you would be so kind to e-mail me your e-address, I will forward the original fuel analysis results to you. The full reports are much more forceful in presentation in that they graphically compare results with target ISO, etc. My e-mail address is avlube@netwalk.com.
Gosh, it sounds like you have an incredible dealer working with you! Most of the dealer folks I talk with have absolutely no interest or understanding of what we are working on!
George Morrison, STLE CLS

[ 11-01-2002: Message edited by: george morrison ]</p>

**srubrn** · 11-01-2002, 14:57

Here is a e-mail I received from a Balwin Filter Engineer. I thought someone had said earlier that this was not the case on the filter, maybe it was Greg. I can't remember. Anybody have any speculations as to whether the following statement is true? This BF7727 is Baldwin's OEM replacement filter for the Duramax.

The BF7727 is 95% efficient at 2 micron. If you have further questions, please feel free to contact us.

Thanks,
TRAVIS R. WINBERG
Service Engineer

LanduytG · 11-01-2002, 18:52

Baldwin says it is 2 micron, but their is only one true way to find out and thats put one on and do a sample analysis. So far the Racor and Cat filters are proven to be 95% at 2 micron.

Greg

**George Gozelski** · 11-01-2002, 20:45

Does Racor make a replacement filter for the Dmax or do you have to add one on in addition?

**george morrison** · 11-01-2002, 22:36

As Greg pointed out the Racor "S" series has proven to be an excellent filter; 95%+ effective for the 5 micron and greater size spectrum which is our target. The regular Racor's, however, are pretty much the same as OEM and are comprised of simple cellulose filtration. To achieve the level of filtration and capacity we need, the filter has to be constructed of a synthetic or microglass type media. The CAT and Racor "S" are synthetic or a synthetic blend type media. If only we could get CAT to expand its filter line we would have that filtration level.. But, CAT recognized the lack of quality fuel filtration and had to go out and build a factory to make filters capable of achieving the level of quality/filtration needed for maximum fuel system life.
George Morrison, STLE CLS

**srubrn** · 11-02-2002, 07:50

I e-mailed Racor about a possible filter solution and they are sending me free of charge a 645R filter head and a R45S filter. I think it is awsome that they are sending me one free but I don't like having to fill the filter and bowl with fuel when I change it. I most likely won't use it. Too bad they wouldn't send me a 400 series filter with a primer.

Kennedy · 11-02-2002, 08:36

WELL, whaddya know! right under my nose the whole time in the Baldwin catalog!

Thing is I'd suspect it is just a remarked OE filter. Guess I'll have to order one and find out...

**srubrn** · 11-02-2002, 08:39

John,

I e-mailed Baldwin back and ask what the filter media is made of. No reply yet. I just sent it this AM.

**George Gozelski** · 11-02-2002, 12:20

This is great that we have people on this site trying to help other Dmax owners! I commend all of you for digging into this filter thing! I'm about due to replace my fuel filter, so I'll wait until all of the outstanding replies from the previously mentioned manufacturers have been returned! Does anybody know what currently is available from all of the suppliers out there. I think we need to list all of the available fuel filters and rate them when this all gets sifted out!

**srubrn** · 11-02-2002, 12:56

Gozelski,

It appears there will be an additional filter added to our trucks. Racor makes the GM Filter and they sale a filter of there own. Baldwin makes one as well. I think the argument is that none of the OEM replacement filters do a good enough job.
We all are waiting on the final analysis and then George Morrison will source out a filter for our use. You can thank him.

**srubrn** · 11-03-2002, 10:45

Here is a link to a interesting article about clean fuel.

http://www.fleetwatch.co.za/suppleme...ieselDirtS.htm

**george morrison** · 11-03-2002, 11:25

That is an excellent article, one of the few written on the subject of the direct affect fine particle concentrations have on fuel system life and performance. I was surprised to see the author being an employee of Shell in that the major fuel companies are staying away from the fuel cleanliness issue like the veritable hot potato. All major refineries stop filtration at 30 microns. Anything below 30 microns gets a free pass. The 5 to 10 micron particle is our problem size particle. No one is filtering to this size. Likewise, no oil company is GOING to filter to 3 microns as a refineries efficiency, the refinery manager's bonus, is predicated on gallons throughput. Putting a 3 micron final filter would reduce throughput gallonage tremendously and cost the refiner gazillions.. So, we are not going to see any refiner step up, voluntarily, and start ultra fine filtration unless regulated to do so.
Thus my surprise with the Shell employee authoring the article.
So, the responsibility to ensure our injector/pump life rests on our shoulders.. The Duramax fuel system/injectors are going to live through warranty; however, if indeed we have a 65% efficient fuel filter, our fuel system is going to be on constant deterioration resulting in decreased power, increased polution, increased cost and eventual early failure.
Off my soapbox...
George Morrison, STLE CLS

[ 11-03-2002: Message edited by: george morrison ]</p>

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