CP4....If or when?
Fleet Mechanic
Joined: Oct 2022
Posts: 1,822
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From: Dallas Metroplex
Anyway, 15K later (two weekends ago) I swapped the fuel filters after routine 5K changing of the oil. I was expecting a filthy primary filter (based upon what pics I've seen posted on the forum from others), but was amazed at how clean it looked. Appeared new, compared to the replacement. Makes me wonder if fuel additives do indeed help, but I have no baseline from which to compare (wish I would've requested to see the one the dealership replaced, now).
In any case, just throwing my own experience out there, for what it's worth...
Lead Driver
Joined: Feb 2022
Posts: 7,975
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The primary water separation/filter on mine was clean as the new one with 56K on it, the under hood one though was dirty black. I think temperature fluctuations play a big part in that. Clean fuel plays a part in the filters too, always use top tier from truck stops with high turn around. Hot Shots is also used, been using it for a while now after watching Prject Farm test them all.
Hotshot
Joined: Jul 2013
Posts: 14,266
Likes: 2,187
The primary water separation/filter on mine was clean as the new one with 56K on it, the under hood one though was dirty black. I think temperature fluctuations play a big part in that. Clean fuel plays a part in the filters too, always use top tier from truck stops with high turn around. Hot Shots is also used, been using it for a while now after watching Prject Farm test them all.
do you have a 2017 or later?
with 2017’s and later there is some meeting of injector rail return fuel and engine bay fuel filter . No check valves. Nothing to stop injector blow by in the return fuel in the high pressure stream to push its way in front of the filter element and once it repasses the filter element…painting the filter element carbon black. There is nothing to change the high pressure return fuel to a pressure less than the lift pump pressure…so the return fuel from the injectors and the carbon blow by…move freely.
at least that’s what I think.
FTE Legend
Joined: Mar 2017
Posts: 31,882
Likes: 9,176
From: Western NY
do you have a 2017 or later?
with 2017’s and later there is some meeting of injector rail return fuel and engine bay fuel filter . No check valves. Nothing to stop injector blow by in the return fuel in the high pressure stream to push its way in front of the filter element and once it repasses the filter element…painting the filter element carbon black. There is nothing to change the high pressure return fuel to a pressure less than the lift pump pressure…so the return fuel from the injectors and the carbon blow by…move freely.
at least that’s what I think.
with 2017’s and later there is some meeting of injector rail return fuel and engine bay fuel filter . No check valves. Nothing to stop injector blow by in the return fuel in the high pressure stream to push its way in front of the filter element and once it repasses the filter element…painting the filter element carbon black. There is nothing to change the high pressure return fuel to a pressure less than the lift pump pressure…so the return fuel from the injectors and the carbon blow by…move freely.
at least that’s what I think.
Lead Driver
Joined: Feb 2022
Posts: 7,975
Likes: 4,047
That makes sense. The engine top filter has the bypass that goes to the return line where the pre-17 does not. I had to go out and look at the drivers side fuel rail to find it, but I see where the fuel return is, which looks like part of the fuel pressure regulation system at the rear of the rail. I can see if the return pressure is greater than the lift pump pressure causing regurgitation of the fuel and know about how the fuel compresses into carbon when under extreme pressure, so that would explain the black filter.
More Turbo
Joined: Jan 2012
Posts: 740
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From: USA
Why would you wait for the CP4 to fail first and then install the DCR? If, you install the DCR before then you don't have to worry about adding the Disaster Prevention Kit. Just a question.
FTE Legend
Joined: Mar 2017
Posts: 31,882
Likes: 9,176
From: Western NY
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