more fuel filter

**chipper** · 08-20-2003, 21:16

About the middle of April, someone posted some pictures of a post OEM filter mounted on the A/C bracket. I believe it was a Racor. How did this installation work out with regards to the air lock problem.I am considering installing one & I remember this looked like a easy one to service. Does anyone have the URL for this installation. I can't find it in search.

**mackin** · 08-20-2003, 21:18

Lone Eagle .....

Mac

mdrag · 08-20-2003, 21:24

Check Lone Eagle's RACOR ENGINE MOUNTED FILTER post.

**Lone Eagle** · 08-20-2003, 22:24

chipper, I just took a fuel sample tonight and will send it to AV Lubricants tomorrow. I have 9,500 miles without an air/vibration problem. Some that originally liked the location have since voiced concerns about engine vibration changing the filtering quality. I decided a fuel analysis was in order. Should know within the next week. If the results are favorable I will repost the photos. Later! Lone Eagle

**Burner** · 08-20-2003, 22:29

Could you re-post the pic's? I can not seem to get them to pull up?

Thanks,

Burner------->

**chipper** · 08-21-2003, 08:46

Thanks Lone Eagle.I will wait for your results on the analysis & happy to hear you didn't have any of the "trapped air" problems.
I can't imagine engine vibration having any effect on the filtering as CAT mounts theirs on the truck frame which vibrates as much as our engine.

**hoot** · 08-21-2003, 09:04

Originally posted by chipper:

I can't imagine engine vibration having any effect on the filtering as CAT mounts theirs on the truck frame which vibrates as much as our engine.

Engines are mounted on isolation devices. Vibrations cannot be categorized as simply vibrations. There are different types. Studies were sponsored by CAT and it was determined that engine vibration does in fact effect filtration.

A vehicles frame has much different vibration frequency characteristics than the isolated engine itself. Frame vibrations are dampened significantly by suspension components.

The engine itself has direct cumbustion triggered knock that is probably one of the worst kinds of vibrations for a filter medium.

**george morrison** · 08-21-2003, 10:22

CAT found that the vibrations issues are not from the engine vibrations specifically but moreover the harmonic 'feedback' vibrations in the fuel itself. As the injectors fire, pressure builds, releases, those impulses are transmitted back through the fuel medium itself, creating an almost 'ultrasonic' cleaning of the filter medium. This is what necessitated CAT switching from an 8 micron beta 2000 filter medium to a 2 micron beta 2000 medium, laboratory test procedure as the theoretical 8 micron filter should have captured the wear causing 5 to 10 micron size component. However, real world pump and injector life was still unacceptable and CAT went back to the lab to determine just why the 8 micron filter was not capturing 8 micron particles. Thus came the discovery of the back-feed, filter media cleansing phemonena.
Which is very likely the reason we have the unacceptable OEM filter medium on our Duramax. The filter IS a 2 micron beta 200 or so filter IN THE LAB... Real world, quite another matter..
George

imported_ · 08-21-2003, 10:55

I had misinterpreted your original report of the injector pulse filter cleaning phenomenom to be siomething beneficial.

For example, I erroneously thought that this pulsation cleaning would give the position of post-OEM add-on filters an advantage over pre-OEM add-on filters.

Consequently, do you think that when using a pre-OEM add-on filter, that the factory OEM filter would help buffer the pre-OEM filter from these harful injector pulsation?

**ndamico** · 08-21-2003, 12:12

George,

Thank you as always for your expertise.

How far down the fuel lines would another filter have to be in order to avoid the "harmonic vibrations"? If they really do decrease the filter efficiency, would it only happen when the engine was running? Specifically would fuel samples taken via priming pump or operating the lift pump (engine off) show better results since the engine was off and the harmonic vibrations not present?

[ 08-21-2003, 12:48 PM: Message edited by: ndamico ]

**Lone Eagle** · 08-21-2003, 19:47

I picked up a little info from a friend who owns a diesel service center but I am going to sit on it until my sample results come in. I am already out on a limb but not so far I can't jump back without loosing face. Later! Frank

**SoCalDMAX** · 08-21-2003, 20:37

Come on. you can tell us. We won't tell a soul.

Regards, Steve

**56Nomad** · 08-21-2003, 20:46

I picked up a little info from a friend who owns a diesel service
center but I am going to sit on it until my sample results come in.
I am already out on a limb but not so far I can't jump back without
loosing face. Later! Frank

Rumor has it that your friend bought a MEGA

**56Nomad** · 08-21-2003, 20:54

But he is looking for a good lift pump..........

**hoot** · 08-22-2003, 05:30

Careful when comparing the results of studies on CAT engines with none done on the Dmax. Our injection system is totally different. I would venture to guess our system has a whole lot less injection pulse harmonics than a big CAT with HEUI injection (remember only guessing). Our system has a pump specifically designed to minimize pulsing and large fuel rails that help absorb them. And since any filter is located before the pump and rails, there is even more isolation.

I thought I posted this yesterday? Anybody see where it went?

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