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Discussion Starter #1
My good buddy and fellow gear head told me a few weeks ago that he thought that the old DMAX was sounding a little louder and more like a cummins when driving out of the parking lot. From inside the truck I couldn't tell much, if any difference. Niether he nor I could not determine any noise difference at idle. Also after the last few tanks of fuel, my mileage dropped from the high 15 mpg to the high 13 mpg.


Last Night I decided to swap out the fuel filters. Installed the OEM and the post OEM CAT filter, then cut them up for inspection. Holy Crap! Check this out. Obviously having a secondary fuel should be a requirement. Can you imagine the mess I would have had if the CAT was not installed?


BTW, the OEM has 11,240 miles and the CAT has 13,222 miles.






 

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Gee Mitch! Where you getting your fuel? That looks like the stuff on the floor of your horse trailer. Later! Frank
 

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Yep, looks like yoiu are not buying fuel at the right places!!!!
 

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Discussion Starter #4
Truth is Frank, there are no truck stops within 30 miles of the house. I get fuel at a Texaco, Shell, Mobil, Circle K, and ARCO, all are the mini-mart type. When I am on the road I usually try to hit the Flying J stops. Up where you are, you have high use stations, down here in the flippin city its tough to find something that can be called high useage stations. Its a good thing that the CAT is downstream of the OEM. BTW, this morning my gearhead buddy came outside with me and we started it up, put it in gear, and he said "Yep, sounds much better!" Makes me wish I had used ear protection 40 odd years ago when we went shooting! I couldn't tell the difference but he could. Topped of the tank last night so at the next fill up I should notice the difference, if the past is any indicator.
 

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Discussion Starter #5
Chipper,


I know what you and Frank are saying, but its difficult to justify driving 30 miles one way to the closest Flying J truck stop! I just feel damn good about the added protection that the CAT gives me!
 

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I may be missing something here, but it looks to me that either pre or post additional filtering is good in this situation. Are we saying that in Mitchagain's case, there is a benefit to post filtering?
 

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Discussion Starter #7
The basic answer is "either, or" just don't rely on the OEM to take care of everything that comes out of the fuel pump!
 

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Both pre and post OEM have turned in some good numbers. Later! Frank
 

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Looks like they redesigned that OEM end cap that might fall off. Looks thicker to allow more glue. Looks like the Cat caught more trash even as a secondary so I guess the media still ain't up to snuff.
 

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has anyone bought one of the slightly longer filters and cut one open? i'd like to see some pictures.. if it hasn't been done i'll pick one up and do the dissection..
 

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Thought Mitch's was the longer one. On second look it does look stretched. Has anyone used the long one on the earlier model trucks?
 

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a bear said:
... Looks like the Cat caught more trash even as a secondary so I guess the media still ain't up to snuff.
I wonder if the sludge that's rumored to cause injectors to stick open are asphaltines that get by the filter???

 

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Discussion Starter #13
I looked closer at the CAT last night. The black crap is not sticky like an asphaltine, and it did not rub off the filter media. Like I stated earlier, Pre or Post secondary really isn't much of a discussion, though I feel much better about the post OEM position. I have to say that one of the biggest points of interest to me was that the CAT had stopped contaminates the full length of the filter media whereas the Racor seems to do its filtering just below the input ports of the filter (hence the wide "stripe" of darkness on the Racor) and then from the bottom up. The CAT has entry holes the full circumference and that may be why all the media is filtering the crap.


I am amazed at how much crapola got thru the Racor. BTW it is the original "short" Racor filter. I suspect that there a several hundred thousand of those that have to be purged from the logistics system before the longer Racor units become readily available. But, if the same media is used, there will be damn little benefit if pictures like this are any indication.
 

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Interesting observation--the OEM filter clearly is not doing its job--but it seems that it could really break down as it is loaded up with junk. I saw some brownish areas--not black--on the OEM filter--yet most of the media on the post CAT was used--blackened.


In my setup(pre OEM CAT)-- after 6Kmiles--my OEM filter was not even black--now that could be more because of my fuel source. But the main point here--the recommended change interval is clearly not sufficent---especially when you have to use fuel from non-ideal sources.


I also interpret the photos as saying--if you let the OEM take on the fuel first--it could become less effective quicker--than if you let the CAT take on the fuel first (pre OEM).


Ron
 

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The LLY filter will not fit the LB7 without a little mod. Like I said before: Why would we want to use them? Later! Frank
 

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Discussion Starter #16
I'll tell you what, the guy that built the interface flange that mounted on the OEM filter head so that he could install a different type of filter may have the best idea of all. If I had the equipment, I would make an adapter so I could put the CAT in the OEM's place. It would have to have 2 O-rings in place of just the one, but that is not an insurmountable situation. Oh well, shoulda, coulda, woulda!
 

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I agree with all said above. Why pay more money for a longer filter with the same crappy media and a lower plate that may fall off and trash the injectors. I know of 3 for sure between here and the DP that fell apart and we represent only a small fraction of these trucks on the road. Any way you look at it it's like rolling the dice. The only thing I felt positive about was the WIF sensor and even it doesn't work. I figure about 3 more of these and I'll be at 100K then that garbage is out of here. The sad part about it is that I have to pay about $20 a pop for these last ones I need and as I install them I'll know they aint worth a nickle.
Edited by: a bear
 

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Discussion Starter #18
RonJT,


You have a valid point. The up side is also, the CAT filters are a minimum of 1/2 the price of the Racor, regardless whose name is stamped on the side. I got the CAT at $10.51 and the Racors off Ebay for a total of $19 ($59 for 3 including shipping). So a Pre OEM CAT makes good sense. That's the way my dad is installing his. Like Frank says "why use them?" --- gotta fill the void with some thing. Too bad its so damn high priced.
 

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Those stations your using....Are they dumping their drain oil in the tanks? Thats a serious amount of dirt there!

Look at it this way....The OEM just catches the BIG chunks, while the secondary filter will filter out the fines. Thats why post seems like such a good idea rather than pre.

Do you think GM knows about all this filter stuff? And how bad the stock one really is? When will they realize that proper filtration would save them money on all the warranty work they're doing to the injectors and I/P.
 

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I guess I should have just come out and say what the more experienced folks have been saying--the OEM filter is junk. The WIF sensor does not work--I saw some posts that the owner had water in his fuel--damaged the injectors and the sensor never alerted him. Then GM said it was his fault because he had bad fuel.


From my little experiement--I have concluded that Pre-OEM CAT is best because I do not have to waste money on the OEM filter. The CAT will catch it all--big and small. Post-OEM you have to replace the OEM on a more aggressive schedule.


I also purchased--from Greg--the RACOR kit--mainly because it has--I believe-- a better WIF sensor. Now I really do not need the OEM filter. I wish there was an adapter to just bypass it completely.


Ron
 
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