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Discussion Starter · #1 ·
I have 10k miles on a dual pleat filter and cut it open. I have an auxiliary lift pump, so the entire filter media surface gets used.

The media starts off white. The first layer was black after 10k miles, and the second layer (same paper media) was brown, indicating that it was trapping dirt that was missed by the first layer. I also saw a couple of spots on the second layer that were quite black, indicating that there were weak spots or holes in the first layer that led to dirt getting past layer 1 and depositing on layer 2. I think this design is an improvement over the old filter, but I would never remove my Kennedy MEGA filter. Anyone else try opening one of these? SPICER
 

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I have one in now, but won't be changing it untli about April. Once I change it, I will cut it open as well to see it's performance.
 

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Spicer,
Pre or Post Secondary Filter?
 

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Discussion Starter · #5 ·
Spicer,
Pre or Post Secondary Filter?
Secondary filter is a post-OE filter. If it was a pre filter I would expect little staining on the OE media. I am a firm believer in the standard concept of using the coarse filter (OE) first and the fine filter (MEGA) next in line. The other way around is bass ackwards if you ask me. SPICER
 

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What difference does it make regarding the order of filters? pre/post etc. in the end the fuel is going thru both filters correct? Not trying to be a smart ass ...just curious. I run a cat pre-filter just because it was easier to mount on framerail and much easier to change then OEM filter...and my OEM filter lasts much longer.
 

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What difference does it make regarding the order of filters? pre/post etc. in the end the fuel is going thru both filters correct? Not trying to be a smart ass ...just curious. I run a cat pre-filter just because it was easier to mount on framerail and much easier to change then OEM filter...and my OEM filter lasts much longer.
You are correct, and a lot of the fuel is getting recirculated so it's getting more than one pass. However, imagine if you will, that you are screening gravel. You run ALL the gravel through a fine screen, say 1/4", THEN you run the screened 1/4" product through a second 1" screen. Kind of a waste of time and effort to run 1/4" gravel through a 1" screen, no?;) That's what you are doing with the finer filter first, basically defeating the purpose and wasting time with the second coarser filter.
 

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Secondary filter is a post-OE filter. If it was a pre filter I would expect little staining on the OE media. I am a firm believer in the standard concept of using the coarse filter (OE) first and the fine filter (MEGA) next in line. The other way around is bass ackwards if you ask me. SPICER
Exactly.
 

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That makes sense ...but what if both filters are, say 2 micron? First filter traps most particles but lets some thru ... 2nd filter traps whatever is let thru. Filters aren't 100% efficient are they?

On edit:

Changed " Filters are 100% efficient are they?" to " Filters aren't 100% efficient are they?"
 

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You are correct, and a lot of the fuel is getting recirculated so it's getting more than one pass. However, imagine if you will, that you are screening gravel. You run ALL the gravel through a fine screen, say 1/4", THEN you run the screened 1/4" product through a second 1" screen. Kind of a waste of time and effort to run 1/4" gravel through a 1" screen, no?;) That's what you are doing with the finer filter first, basically defeating the purpose and wasting time with the second coarser filter.
Your example assumes the the pre-filter has a smaller micron level then post filter. For example 2 -> 5 micron. It does make sense the 2 micron filter is going to be doing all the work. But what about a 2 -> 2 micron setup? I don't think anyone would put the smaller micron filter first but MANY put a filter with the same micron rating before the OEM ...in this case I would argue this would filter better then a 5 -> 2 setup.
 

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I agree with tophog on this one. As long as its filtered who cares how it gets that way? The bonus with the smaller one being first is the Cat filters are cheaper than than the OEM ones.
 

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BTW, I'm not trying to start an argument :) My dad has had semi's for years and still does today. He also firmly believes in the bigger -> smaller micron filter scenario where the pre-filter filters the "chunks" and the OEM gets the little stuff.

I've just never understood how people can say this is better then 2 filters of the same rating. I can see where you may need to change the prefilter more frequently but as far as filtration efficiency I don't think the 5 -> 2 setup would do any better.
 

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well it's nice to know that they're better than they used to be, however, I've never reinstalled my secondary after my injectors went. I just figure I'll wait until warranty is up on the motor, than reinstall it. I had almost 15k on the 'A' version of the dual pleat, no lift pump, however just about that time I got the freebie change in the mail to the new 'B' and took it in. Yes, I forgot to ask for the old one back.

the upside though, my 2 injectors crapped out at just shy of 25,000, now at 54,000 and they still look good via balance rates so I'm feeling good about it.
 

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lets see some pics
 

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when i was in school we cut a lot of filter apart to do a comparison of different filters from fuel to oil trans oil filters and others and some were good some bad but the one i and everyone thought was the best was the cat fuel filter it had good strong even pleats and it was overall just a great filter so if i were to put a different filter on my truck i would go with the cat filter system that is sold on this site because of the filter
 

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This filter had 8K. First 4K I was on the road, so differant station every stop. The last 4K, almost all the fuel came from the same station.
My fuel system is stock. No lift pumps or additional filters. I have never added anything to the fuel.
On the last Pic, the outer filter is on top.
 

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Discussion Starter · #17 ·
WOW! It looks like the second layer is as dirty as the first! Maybe they need 4 or 5 layers! I have a lift pump so my entire filter media gets used. I don't have the "striping" that you have from a "half full" fuel filter can. Seeing how dirty the second layer is gives good reason to believe that a secondary filter is a must. It also shows how inadequate the original OE was. SPICER
 

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What is the micron rating of the OEM filter anyway?
 

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IIRC is 5 micron
 

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Discussion Starter · #20 ·
IIRC is 5 micron
I know that there was a lot of independent samples and cleanliness tests done on fuel in the past. This was during the "Early Days" of realizing the need for additional filtration and R&D of the first production of a secondary filter setup made by John Kennedy.

Guys were tapping into their fuel lines, sampling fuel before the OE, after the OE, and after the secondary filter. I think the OE Racor claims some really good numbers (do not recall the micron rating) but the numbers "in the field" were far from the Racor claims. Then there is the issue of micron rating and whether it is a "nominal" rating (50% of the particles at that size) or an absolute rating (99% at that size).

Back to the pre-post discussion.....They both work, post is the logical approach, pre is an easier install. If you go pre, it has been found that the filter element may clog sooner, which also makes sense. SPICER
 
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