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Hey guys I'm new here, and by the looks of it so is everybody else.


Anyway..........what is the purpose of the secondary fuel filter? Is it absolutely necessary?


I'm still realtively new to owning a Dmax, just got mine at the end of June and never had one before, so I'm diesel ignorant.



I'm really looking for information to insure my satisfaction with my investment.
 

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Read all about it in the post titled "After Market Fuel Filtration" More information that you can stand.
Edited by: TX-DMAX
 

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With a basic combination of nasty pump fuel and marginal factory filtering, many are putting secondary filters on their trucks to clean up the fuel a little more.

As TX mentioned, the other threads will give you more detailed info (ad nauseum in some cases
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I'm reposting this message to incorporate significant changes due to new, expert, explanations on cavitation.


There are two ways that you can mount an additional filter: Either before, upstream of the factory filter (pre-oem) or after, and downsteam of the fatoiry filter (post-oem).


Fuel filter fuel analysis results posted on TDP indicate the best filtration thus far have been achieved with a pre-OEM filter and the OEM filter.


Many have found that mounting their 2 micton Baldwin and CAT filters post-oem have caused air to be trapped in the filters causing random stalling and "no starts." Inexplicably, the filters that cause stalling in some trucks, work just fine on others. Those mounting their filters pre-oem have not reported any stalling/no start problems whatsoever. The RACOR filter is the only filter I know of that can be mounted post-oem w/o any reports of causing stalling.


Those that have installed post-oem filters found that they could cure the stalling/no start problems by installing a lift pump that prevents the entrained air and vapor found in the fuel from normal outgassing that occurs in our stock fuel systems. Air testing performed by chuntag95 indicate that even stock systems produce outgassing and air in our fuel systems - it's normal.


Some will try to selll you a lift pump to eliminate this air claiming that it could cause cavitation. Experts contradict this stating entrained air and outgassed air bubbles do not cause cavitation - airless cavities or voids in the fuel caused by vacuum, and not entrained air or air bubbles, cause cavitation.


For example, when there is suction but not enough fuel to feed a pump, a cavity or void occurs. When pressure is reapplied, this cavity violently collapses which can etch and damage metal.


Moreover, in fact, there has not been a single report of any cavitation problems in the stock Duramax or in Bosch common rail injection fuel systems that I have seen.


To the contrary, evidence points to the opposite conclusion that the Bosch commoin rail fuel sytem is highly reliable. Reports indicate that with properly filtered fuel, our fuel systems should perform reliably, well past the expected service life of the truck. For example:


BROKERS, a long haul car broker, has claimed 2 of his Duramax trucks have gone over 400,000 milies (800,000 combined) with only one injector failure between them.


BROKERS stated that he uses two filters: One filter in the bed with his auxuliary tank and one frame rail mounted RACOR 2 micron filter. He transfers his fuel from the bed tank to the OEM tank, BUT DOES NOT HAVE A LIFT PUMP.


To-date, no one has reported any Bosch common rail injection system fauilures due to cavitation in any forum or reference that I have been able to find. If the design were poor, and if entrained air caused cavitation, the entrained air normally found in diesel would still cause cavitation on a moleular level.


Apparently, Bosch knows their diesel injection stuff. GM dumped their long standing injector suppliers for the Bosch common rail system and in 2003, so did Dodge. Our common rail system is also used in Mercedes, Alfas, Volvos and VW's.


Bosch has been making diesel injection systems since 1922. Bosch began marketing their common rail injection system in 1997. There are 3,500,000 Bosch common rail systems in vehicles in the U.S. and over 10,000,000 world-wide since 1997. Therefore, with so many common rail systems in real life use, if there was a cavitation problem, I feel it surely would have been reported and common knowledge by now.


There are vendors who have sold many post-oem filter kits only to learn that their filters trapped air that caused random stalling. I had ordered one and this vendor did not warn me about the air/stall problems when I
 
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