CP4 to CP-ISB21S3 (revised CP3) change for 2021 6.7L Diesel Trucks -- Merged Threads

[mra400ex]

In response to the ones who claim this is just an issue that is not that big of a deal. I live in Southern IL and 2 independant diesel repair shops that have an excellent reputation know all about it. One in Paducah, KY is who informed me about the issue. I Googled it and it is everywhere. His recommendation is that as soon as your warranty expires you better do the CP3 conversion. He has made a living off the Duramax and Ford CP4 failures. Said he is recommending the bypass kit if you own a Ford regardless. For now the best we can use is the recommended fuel additive. Don't run below 1/4 tank (to prevent aeration). And buy your fuel from a station where you know the fuel quality is good. Unless FCA comes out with a recall fix the only other thing is to keep your fingers crossed

 

[TonyG]

So for those that haven’t bought yet, get the 2021. The 2021 (verified just a little while ago) has the CP3. So no need to deal with a recall etc.

[MOD EDIT: ​

Any complaints or rants about the CP4 may be messaged in one of the other three or four threads along those same lines or the following thread:​

​

https://hdrams.com/forum/index.php?...fuel-pump-free-range-just-keep-it-civil.3515/ ​

​

PLEASE stick to the technical, TSB, and/or recall aspects of this issue. ​

​

This is not directed at the OP, it is intended for those new to the thread]​

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These are GREAT news!

 

[TonyG]

These are GREAT news! Now I can get exactly what I want.

 

[NDanecker]

Why are you worried about this switch? Hydraulic lifters have been around forever and are nothing new. I think most (close to all?) engines use hydraulic lifters now a days don't they? As long as you're doing your maintenance you've got nothing to worry about.

{insert hemi lifter issue}

Although I believe Cummins spec'd and manufacturing the lifter design I am still moderately concerned. Yes, hydraulic lifters have been around for years but that theory certainly doesn't hold water with the Hemi lifter debacle. Material, bearing size, oil viscosity, forces exerted on lifter from valve spring, etc. So many variables that come into play more so than the concept has been around for years. I trust Cummins has done their homework, and hoping they are pulling this design from other motors they produce that are known to work. I just hope its not FCA requesting them to quiet the motor down and this is their solution (even though it may not be a good one or recommended by Cummins). Remember - FCA (whos' buying the motor) drives the spec.

 

[Brewbud]

The fact that FCA pays people (Ramcares) to monitor the forums shows that they do listen and are interested in feedback. Whether they act the feedback or not is another question. I do know that many of those driving a Ram right now are doing so because they bailed on Ford and Chevy for having problems. Ram is number two now for truck sales and I am sure they would like to maintain their momentum. Marketing, failure analysis and keeping an eye on public opinion should help management point the engineers in the right direction (fingers crossed).

 

[Cseybert]

They also have new owners as of this week.

 

[Brutal_HO]

I'm going to remind everyone that this thread needs to stay on topic regarding the CP4 to CP3 change and potential TSB or recall discussion.

The bickering, veiled insults, and off topic discussions need to stop or the thread gets locked. They are not constructive and we are rapidly approaching a point where the thread has run its course and is no longer providing a benefit to the membership.

Thanks for your understanding and cooperation.

 

[UglyViking]

{insert hemi lifter issue}

Although I believe Cummins spec'd and manufacturing the lifter design I am still moderately concerned. Yes, hydraulic lifters have been around for years but that theory certainly doesn't hold water with the Hemi lifter debacle. Material, bearing size, oil viscosity, forces exerted on lifter from valve spring, etc. So many variables that come into play more so than the concept has been around for years. I trust Cummins has done their homework, and hoping they are pulling this design from other motors they produce that are known to work. I just hope its not FCA requesting them to quiet the motor down and this is their solution (even though it may not be a good one or recommended by Cummins). Remember - FCA (whos' buying the motor) drives the spec.

I don't think that comparison is a fair one. To my knowledge the hemi lifter issue seems to stem from the MDS. Hemi also uses an OHC where as the cummins is OHV. I know that GM had similar issue with lifters failing on their MDS systems for the first gen ls that included it. I don't think it's quite an apples to apples comparison here. Plus you could list out basically every other manufacture and model where this isn't an issue (including those in FCAs own lineup).

At least for me, not a concern.

 

[NDanecker]

Good video of comparison. After seeing the difference I would like to slap the person who designed the CP4 pump (and I've done machine design for 18+ years). The CP4 is a poor design....period.

 

[Xflight29]

Well said.Becasuse it makes people like you feel like they are listening (and care) suggesting to see a dealer with issue(s), but then deny legitimate CP4 claims stating fuel contamination. Honestly, how has RamCare helped other than say they are sorry you are having the issue and you should see a dealer? Isn'

Why are you worried about this switch? Hydraulic lifters have been around forever and are nothing new. I think most (close to all?) engines use hydraulic lifters now a days don't they? As long as you're doing your maintenance you've got nothing to worry about.

I

Why are you worried about this switch? Hydraulic lifters have been around forever and are nothing new. I think most (close to all?) engines use hydraulic lifters no

The bottom line nobody really has any factual information other than there have been failures, and that RamCares recently says a fix is in the works. No lawsuits have produced any results yet with factual numbers from Ram, and I think I saw on here that the GM suit started in 2013 and hasn't been resolved yet. Nobody knows out of several hundred thousand 19-20 Ram trucks, how many have had failures in the US or Canada. Nobody knows how many failures were low or high mileage, real fuel contaminated, is it really a poor designed pump or poor quality US diesel fuel causing the failure? Everything has been speculation, opinion, he said she said, dealer said, Facebook said, after market vendor said, yet the only source that really knows is Cummins and Ram Trucks. Which may be the reasons the 21's have the CP3. We've seen a few posts here with low mileage failures, yet we have owners with high mileage trucks with no issues at all. So maybe my 19 pump with 7300 miles will fail, maybe not, but either way I'll drive it and not worry about it till such time I would have to deal with whatever part fails. When Ram has a fix then we'll all know there is a fix, and whether it'll be a recall with a CP3 or the large dimple CP4! If you weren't driving a Ram, you'd be dealing with another truck manufactures problems, so no matter what forum site you read, there will always be Gloom and Dome or the Sky is Falling!

 

[Xflight29]

Well said.
Thanks.

 

[exiledinaz]

Not sure how people keep missing the connection between safety issue and sudden engine stoppage.

Y'all even tow? How'd you like that thing to spray glitter while you're hallway down the Grapevine, Davis Dam, Ike pass...etc with your family riding and a 10k RV pushing on you in tow?

Only 10K RV in tow? My new one is 18K........The thought of the engine quitting from a well known issue with a injector pump is maddening. Safety would be more of a reason. Hope anyone who suffers that puts a NHTSA complaint in..

 

[NDanecker]

If you review the video I posted above you can see the majority of CP4 failures occur as a result of cam/follower failure. This is most likely due to containments getting caught inside the follower roller bearing preventing it from rotating which is identical to the cam lifter failure in early Hemi's. Later hemi motors received a redesigned lifter with a larger inside bearing which could overcome containments that may pass the filter and get caught inside the bearing preventing the roller from spinning thus wiping out the cam. CP4 pump is identical issue. IMO CP4 has 3 major flaws. One the follower bearing/bushing has 2 small of an OD. Two the inside bearing needs to be larger so it is not as susceptible to containments. Three the follower assembly should not be allowed to completely rotate. Although the bearing is very wide and it naturally wants to keep centered or straight it should have a catch in the event is does try to spin.

I also believe the fuel filtration system cannot keep a 'clean' supply of diesel fuel which is required for the CP4 pump to function. CP3 is more forgiving. I bet FCA did not upgrade the fuel filtration system when they switched (maybe someone can confirm).

 

[roflcopter]

I don't think that comparison is a fair one. To my knowledge the hemi lifter issue seems to stem from the MDS. Hemi also uses an OHC where as the cummins is OHV. I know that GM had similar issue with lifters failing on their MDS systems for the first gen ls that included it. I don't think it's quite an apples to apples comparison here. Plus you could list out basically every other manufacture and model where this isn't an issue (including those in FCAs own lineup).

At least for me, not a concern.

The hemi is a pushrod OHV motor just like the Cummins... you don't have lifters in an OHC motor.

 

[UglyViking]

The hemi is a pushrod OHV motor just like the Cummins... you don't have lifters in an OHC motor.

Man did I write some stupid stuff right there. I was way off. I thought the hemi was an OHC but I was flat out wrong there, so good catch, ignore me there.

What I meant to say wasn't lifters failing, but the MDS valves. Whatever valves that GM used to use, and assume hemi is using a similar style where they can do cylinder deactivation, those valves can fail causing issue.

Either way, you're spot on, I came off pretty dumb right there. I swear I know the difference

P.S. as I was typing this I had to stop myself from typing lifters twice, I don't know why that is what my brain keeps going to.

 

[NDanecker]

Man did I write some stupid stuff right there. I was way off. I thought the hemi was an OHC but I was flat out wrong there, so good catch, ignore me there.

What I meant to say wasn't lifters failing, but the MDS valves. Whatever valves that GM used to use, and assume hemi is using a similar style where they can do cylinder deactivation, those valves can fail causing issue.

Either way, you're spot on, I came off pretty dumb right there. I swear I know the difference

P.S. as I was typing this I had to stop myself from typing lifters twice, I don't know why that is what my brain keeps going to.

Do you mean solenoid valves that control oil flow to the MDS lifter? I don't believe that was ever an issue. The issue is with the roller on the lifter itself, not spinning and then wiping out the camshaft lobe. I never seen or heard of an issue with the MDS solenoid valves that control oil flow.

 

[UglyViking]

Do you mean solenoid valves that control oil flow to the MDS lifter? I don't believe that was ever an issue. The issue is with the roller on the lifter itself, not spinning and then wiping out the camshaft lobe. I never seen or heard of an issue with the MDS solenoid valves that control oil flow.

No, what I was trying to say was the piston valves for the GM trucks (which upon looking up I see is called AFM/DOD not MDS), but it turns out it wasn't even the valves, or at least not that I could see. I swear I thought that there was a design GM used where there were special valves used instead of the lifter design for a few of the cylinders but I'm not finding anything online, so I guess I'm 0 for 2 at this point.

So, to close this loop since it's not quite the topic of discussion:

• Dodge and GM both use OHV designs for their engines, neither use OHC (sorry I got it wrong mopar guys!)
• Dodge and GM both had issues with their MDS/AFM systems, and it looks like they both related to a similar issue around the lifters from what I can tell
• Cummins shouldn't have an issue with hydraulic lifters as the issue for dodge and gm was the lifters with MDS/AFM not the system as a whole
• I'm apparently a bit of a dunce

Unless brought up again I'm just gonna take the L here and move on, I apparently misremembered something pretty poorly.

 

[NDanecker]

We all make mistakes. That is what makes us human.

Cadillac tried cylinder deactivation back in the 80s with their 8-6-4 motor. It was a complete failure. Almost bought one thinking damn ....that is cheap for a caddy. Glad I didn't. Didn't have the internet for research so had to find a mechanic you trusted for advice. Pretty sure they used some form of a electric solenoid at the valve instead.

 

[Ostracize]

No, what I was trying to say was the piston valves for the GM trucks (which upon looking up I see is called AFM/DOD not MDS), but it turns out it wasn't even the valves, or at least not that I could see. I swear I thought that there was a design GM used where there were special valves used instead of the lifter design for a few of the cylinders but I'm not finding anything online, so I guess I'm 0 for 2 at this point.

So, to close this loop since it's not quite the topic of discussion:

• Dodge and GM both use OHV designs for their engines, neither use OHC (sorry I got it wrong mopar guys!)
• Dodge and GM both had issues with their MDS/AFM systems, and it looks like they both related to a similar issue around the lifters from what I can tell
• Cummins shouldn't have an issue with hydraulic lifters as the issue for dodge and gm was the lifters with MDS/AFM not the system as a whole
• I'm apparently a bit of a dunce

Unless brought up again I'm just gonna take the L here and move on, I apparently misremembered something pretty poorly.

Being mistaken doesn't define character, how one reacts after realization does... If above is any indication, stand tall brother.

 

[MtnRider]

I also believe the fuel filtration system cannot keep a 'clean' supply of diesel fuel which is required for the CP4 pump to function. CP3 is more forgiving. I bet FCA did not upgrade the fuel filtration system when they switched (maybe someone can confirm).

Do you believe the fuel contaminants are some how getting "around" the filtration? It's being filtered down to 3 microns (at least 4th gens are) so that's pretty small (human hair is ~70 microns).


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