LML Dans Diesel Work, and CP4 failure

aklbz

Member
Jan 8, 2015
126
0
16
IMO, it's best to do a water separator, then lift pump, then tighter 2 micron filter, all back by the tank on the frame rail. Anyone that is just running a cat filter in stock location with no water separator is eventually asking for issues.

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Burn Down

Hotrodder
Sep 14, 2008
7,092
28
48
Boise Idaho
Yes i was refering to the CAT filter not being a water seperator. What people fail to tell you when you order a kit to convert to those filters is that they aren't a seperator and you absolutely have to be running a lift pump setup with a water seperator, specially if you still have a cp4 in your truck...I ran those CAT filters on my fass and they sucked and gelled up big time, I had a few and since they were so cheap they just went in the garbage.

Why do you think they gelled up? The fuel gels from not being blended properly for current weather conditions. The tighter/better filtration filters are going to amplify this problem as they will absolutely gel faster than a looser filter but saying they suck and are garbage because they gelled is a pretty dumb statement. If you want to be pissed, be pissed at the bulk plant blending the fuel;)
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,637
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113
Phoenix Az
i find it kinda funny you guys say a water separate is so important to the health of the fuel system and keeping the crappy designed first gen CP4 alive. its like saying better filtration keeps LB7 injectors alive :roflmao:. One of two things happens with that separator. either you never drain water from it or the truck died and you are draining water for days from the separator and tank. i have NEVER seen a separator pull water from fuel and when you crack it open, you get some water, then fuel. if you are getting fuel with enough water in it to actually settle to the bottom of the separator, EVERYTHING fuel related hard parts will start dieing and the separator will NEVER get all that water out of the fuel.

you will know when you actually get water in your fuel. its not fun to drive ;)
 

wilrob

Back in the Motherland
Sep 14, 2016
366
0
16
Dallas, TX
I did the filter adapter but run a Donaldson which is supposed to filter better and separate water and I'll say I haven't ever had anything but mostly pure fuel come out when I've drained it
 

Ne-max

I like turtles
Nov 15, 2011
3,361
64
48
Lincoln, Ne
i find it kinda funny you guys say a water separate is so important to the health of the fuel system and keeping the crappy designed first gen CP4 alive. its like saying better filtration keeps LB7 injectors alive :roflmao:. One of two things happens with that separator. either you never drain water from it or the truck died and you are draining water for days from the separator and tank. i have NEVER seen a separator pull water from fuel and when you crack it open, you get some water, then fuel. if you are getting fuel with enough water in it to actually settle to the bottom of the separator, EVERYTHING fuel related hard parts will start dieing and the separator will NEVER get all that water out of the fuel.

you will know when you actually get water in your fuel. its not fun to drive ;)

Its common in the midwest where the climate is always changing. I have drained water out of mine and many of my customers trucks.
 

WVRigrat05

Wound for sound
Jan 1, 2011
3,081
4
38
36
French Creek, West Virginia
Sounds like he was excited for the work done and then his truck ****ed up and dan helped him diagnose the issue and got him the parts he needed fast, don't see any negative comment towards anyone about why it failed
 

aklbz

Member
Jan 8, 2015
126
0
16
Everything breaks...eventually

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CarolinaHD

Member
Feb 8, 2011
969
6
18
NC
Sounds like he was excited for the work done and then his truck ****ed up and dan helped him diagnose the issue and got him the parts he needed fast, don't see any negative comment towards anyone about why it failed

True, went back and reread it.
 

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,187
354
83
At Da Beach
i find it kinda funny you guys say a water separate is so important to the health of the fuel system and keeping the crappy designed first gen CP4 alive. its like saying better filtration keeps LB7 injectors alive :roflmao:. One of two things happens with that separator. either you never drain water from it or the truck died and you are draining water for days from the separator and tank. i have NEVER seen a separator pull water from fuel and when you crack it open, you get some water, then fuel. if you are getting fuel with enough water in it to actually settle to the bottom of the separator, EVERYTHING fuel related hard parts will start dieing and the separator will NEVER get all that water out of the fuel.

you will know when you actually get water in your fuel. its not fun to drive ;)

I drain water from separators weekly on boats, I can assure you that they work just fine if properly maintained...
 

Dozerboy

Well-known member
Jun 23, 2009
4,892
470
83
TX of course
X2 we do it all the time in my industry. In fact I have never had a fuel system failure due to water. And I've had so much water in a tank we where draining it twice a day.

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WVRigrat05

Wound for sound
Jan 1, 2011
3,081
4
38
36
French Creek, West Virginia
X2 we do it all the time in my industry. In fact I have never had a fuel system failure due to water. And I've had so much water in a tank we where draining it twice a day.

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Those dozers especially love to make water, I drained gallons of water out of our D6's when we still ran them.
 

drperry

New member
Jan 4, 2015
21
0
1
The more fuel returned, the more potential for condensation. When we park our big rigs for the night, it's always with a full tank of fuel to reduce the amount of possible condensation...

Not to mention days that go from below 0 to 70 above, and back below 0, lol.

It's not always from bad fuel :)
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,637
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113
Phoenix Az
No one here other than ne-max has made an apples to apples argument one the water separators on these trucks. Imho, they suck. Had a lbz last year that got a bad batch of fuel. Truck ran like crap and no "water" came out of the separator. We have large temp swings out here in AZ from 60* in the morning to 90* by 2pm. I've also been/lived in colder climates and still never got any water from my stock separator when I had it.

Either way, even if you DID get water from it, it sure as hell is not the main cause of the cp4 failing. Just like more filters will not keep older style lb7 injectors from failing
 

WVRigrat05

Wound for sound
Jan 1, 2011
3,081
4
38
36
French Creek, West Virginia
No one here other than ne-max has made an apples to apples argument one the water separators on these trucks. Imho, they suck. Had a lbz last year that got a bad batch of fuel. Truck ran like crap and no "water" came out of the separator. We have large temp swings out here in AZ from 60* in the morning to 90* by 2pm. I've also been/lived in colder climates and still never got any water from my stock separator when I had it.

Either way, even if you DID get water from it, it sure as hell is not the main cause of the cp4 failing. Just like more filters will not keep older style lb7 injectors from failing

I wasn't trying to make a comparison, I've drained water out of my truck one time, it was from a drum I fuel in, put probly 6-7 gal of water in the tank and drove it 200+ miles. Far enough to have to fill up again and it smoked and knocked.
Pulled the fuel filter and it was full of rust water. It ate my injectors slowly.

Other than that, I have never seen a drop of water in my filter.
 

99mpower

Bear Motorsports
Sep 2, 2016
53
0
0
Active duty explains a lot. No common sense. :hug:

RIGHTTTTTTT... :roflmao:

Yes i was refering to the CAT filter not being a water seperator. What people fail to tell you when you order a kit to convert to those filters is that they aren't a seperator and you absolutely have to be running a lift pump setup with a water seperator, specially if you still have a cp4 in your truck...I ran those CAT filters on my fass and they sucked and gelled up big time, I had a few and since they were so cheap they just went in the garbage.

didnt know.. learn something new everyday. Figured a better filter would be better for the fuel system. Wish they made that stuff more clear when you convert it over

IMO, it's best to do a water separator, then lift pump, then tighter 2 micron filter, all back by the tank on the frame rail. Anyone that is just running a cat filter in stock location with no water separator is eventually asking for issues.

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Would be nice to run a tighter filter back by the tank, but I've got what I've got now, and its staying.. haha

Sounds like he was excited for the work done and then his truck ****ed up and dan helped him diagnose the issue and got him the parts he needed fast, don't see any negative comment towards anyone about why it failed

yep... exactly

Everything breaks...eventually

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very true. I do tons of work on BMW race cars, and no matter what, SOMETHING is going to happen. Parts fail, stuff breaks, nothing you can do about it, but order parts and fix it.. oh well. Better off in the long run :thumb:


I tore down the old CP4. It was definitely hurting. Pictures will be posted later today.
 

LBZ

Super Moderator
Staff member
Jul 2, 2007
9,903
149
63
46
B.C.
X2 we do it all the time in my industry. In fact I have never had a fuel system failure due to water. And I've had so much water in a tank we where draining it twice a day.

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X3
Water separators work. They strip the water out of the fuel and collect at the bottom to be drained. If you don't drain them enough though, you can force it through the filter-usually about the same time you notice running issues. And by then it's too late.

I don't trust the gm water separator because the filter itself isn't a separator filter. They just added a bowl. Proper separator filters are higher number micron and have a different membrane in them to strip water molecules.

As someone who has run thousands of gallons of rig fuel through his truck, and plugged many a water separator filter off with water from bad fuel, i can assure you they are necessary in any diesel.

Myself, my fuel gets filtered 4 times before it hits the cp3.
 

Dozerboy

Well-known member
Jun 23, 2009
4,892
470
83
TX of course
Just a bowl will go a long ways. That's all our old tractor had and that's all my drag up tank has. I've seen them pull water out. That still not a good comparison, but I'm not going to test it to see how it works.

This might speak to how good of an idea it is to run a good fuel additive.


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nick31

New member
Apr 14, 2016
32
0
0
Why do you think they gelled up? The fuel gels from not being blended properly for current weather conditions. The tighter/better filtration filters are going to amplify this problem as they will absolutely gel faster than a looser filter but saying they suck and are garbage because they gelled is a pretty dumb statement. If you want to be pissed, be pissed at the bulk plant blending the fuel;)

They don't even filter better...and it wasn't my fuel, I live in MN fuel is plenty blended and I ran optilube winter additives. Im not the only person to have issues with CAT filters on a lift pump. Changed to different filters and never had another issue