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

[Bocephus]

Thought this was cp3 info only page?

 

[HD5280]

Dude was respectful, no need for salt.

Shows more evidence this CP4 nonsense is more than just failure rate talking points. Perception is reality. Ram should get on the ball soon. No more BS. Fast track it and get it done. "Service solution" mystery talk has already worn thin. Another month and it will be time to gather the forks.

Fair, but it is also the typical “I need to justify my Ford purchase” post. We get it. You want to feel like you didn’t just make a horrible decision switching to Ford who has just as many issues as Ram.

The better approach is probably simply saying that the fuel pump issue made him waiver and change brands. Rather than needing to justify by claiming everyone he knows with a Ram has issues. Silly.

 

[Brutal_HO]

What does the CP3/CP-ISB21 do for fuel return to be different than the CP4?

The 4 sends blown bits to the engine and injectors, where does the 3/21 send it to?

In short, the pump mechanicals are isolated from the fuel supply input/output.

Best video I've seen (looks to be a rear mount industrial CTD)

 

[Brutal_HO]

Here's another that many have probably already seen.

He covers that basics but doesn't go into a lot of detail about how the fuel flow is routed.

 

[Rob122]

Have there been any updates from Ram Cares on a possible retrofit?

 

[MtnRider]

Have there been any updates from Ram Cares on a possible retrofit?

Saw a guy with a failed pump post up that his was repaired 2 weeks ago with another CP4 so it doesn't seem promising to me that they are going to retrofit the trucks with the new pump.


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[Brutal_HO]

Have there been any updates from Ram Cares on a possible retrofit?

No.

Not quite 60 days yet... Let's hope they announce something in March.

Hello everyone, we would like to relay the latest update to you here regarding your concerns with the CP4 pump. There is currently a service solution in progress for all 2019- 2020MY vehicles equipped with CP4 high pressure pump. Further updates will be announced here as soon as more information becomes available. In the meantime, please know that our team remains available to assist in resolving serviceable vehicle concerns via private messages. Thank you,

Kathryn
RamCares

 

[Brutal_HO]

Saw a guy with a failed pump post up that his was repaired 2 weeks ago with another CP4 so it doesn't seem promising to me that they are going to retrofit the trucks with the new pump.


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Why would they do something that's not yet a TSB/recall?

 

[MtnRider]

Why would they do something that's not yet a TSB/recall?

Why would they not? They have a solution and the parts to do it already (already fielded in the '21 trucks). It may not be an official recall yet but they have a way forward if that was the direction they planned to take (retrofit). Which lends to my point that "I" don't think they will retrofit them, they are still looking for another solution/work around for the existing trucks.

But my speculation is no better then your speculation so who knows.....


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[str_8_shot]

Why would they not? They have a solution and the parts to do it already (already fielded in the '21 trucks). It may not be an official recall yet but they have a way forward if that was the direction they planned to take (retrofit). Which lends to my point that "I" don't think they will retrofit them, they are still looking for another solution/work around for the existing trucks.

But my speculation is no better then your speculation so who knows.....


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Correct, I’m willing to bet money we’re stuck with these CP4 trucks... If you’re “lucky” enough that it fails during warranty period, you get another CP4 to get you out of warranty.

 

[Epsilon Plus]

They wouldn't have given the go ahead to just one random dealer somewhere before an official release, especially one with this many eyes on it. One guy gets a CP-ISB21, and another guy a few states over gets a dimple the same day and they both post and all hell breaks loose.


Rumor from one of the Brutal linked sites was that 2021 engines produced but not installed got their CP4s stripped off and retrofitted before they shipped out to Ram and if that's true, the retro IS possible and there is a CHANCE of a recall utilizing such parts/methods.

Until the official word comes out, the silence is very loud.

 

[Epsilon Plus]

I would also surmise that the CP-ISB21 is just an upgeared CP3. The CP4 runs at 1.5x the engine RPM. S&S likely made a new sprocket with a similar overdriven ratio for the CP3 for their retrofit. Cummins with this ISB21 likely did the same thing. But because it's not identical, it gets a new name and P/N. An unoriginal one at that. ISB is the longtime 5.9/6.7 engine designation.

-OR-

The reason for the different front cover up front could be that the drive gear from the timing set got the ratio change. Dunno.

Either way they had to find a mechanical way to ramp PSI/BAR on this pump. Perhaps there are some small improvements internal compared to a CP3 as well.

I just want it not to glitter party my fuel system. Call it what you want, gear it how you want, just make sure when it fails, its the only thing that does.

 

[Will_T]

Call it what you want, gear it how you want, just make sure when it fails, its the only thing that does.

Seems so easy when succinctly stated like this! I guess I am just old and from the magical school of simple, logical, thinking.

 

[BigOlMega]

Didn't it take them 6 months for a "service solution" on the bed step (actually a recall) that did not involve just removing it? Hopefully this service solution is more thought out....

 

[Brutal_HO]

Didn't it take them 6 months for a "service solution" on the bed step (actually a recall) that did not involve just removing it? Hopefully this service solution is more thought out....

Not sure it was that long, perhaps. However, I would guess that bed steps were more common than Diesel trucks and they also had to build a fix and get it in the pipeline. They also removed and trashed a lot of steps that just needed a new brace.

They already have the pump and the code, and if needed (likely) the front engine cover (maybe scissor gear change?)

The HVAC time from Ramcares initial post to announced TSB was 60 days. If anything happens, it is likely to occur between those two timeframes. My hope is they already have the fix worked out, they just need time to ramp up the logistics and parts availability.

At this point, it's all speculation. IOW, it ain't over until the large and fluffy lady sings.

 

[thestuarts]

Now here is my theory on where the failure occurs.

It’s at the bottom of the stroke where the spring has the lest amount of compression force on the roller that can allow it to pivot or shift (it’s not retained in any position) which results in the roller to be destroyed by the lobe and results in the catastrophic failure

That's the same theory that S&S stated at the 4:15 mark in this video.

I use Hotshots Secret additive, but it won't protect the CP4 if the roller pivots.

Edit: I wasn't trying to imply you took their idea. I just meant you came to the same conclusion.

 

[thestuarts]

That lobe is so wide that it most likely will not rotate considering the aggressiveness of the lobe and centerline of the pump. Issue is the design relying on diesel fuel to create the lubricating barrier between the lobe and small diameter roller. I estimate around 5,000 lbf spread on a very small contact area which will result on almost pure metal to metal contact. The forces are no where near the same on a camshaft/roller design which uses a much thicker viscosity oil allowing a protective film between roller (with larger diameter) and lobe. Particles flowing around the inside of that case also contribute to the roller not spinning or sliding on the lobe. Again - piss poor design IMO.

When S&S performed fault analysis on many failed CP4 pumps, the root cause was lobe rotation. Skip to the 4:15 mark in this video.

 

[UglyViking]

I would also surmise that the CP-ISB21 is just an upgeared CP3. The CP4 runs at 1.5x the engine RPM. S&S likely made a new sprocket with a similar overdriven ratio for the CP3 for their retrofit. Cummins with this ISB21 likely did the same thing. But because it's not identical, it gets a new name and P/N. An unoriginal one at that. ISB is the longtime 5.9/6.7 engine designation.

I highly doubt that is the reason the part number is different. If that were the case then FCA wouldn't have a CP4 but a "CP-letter soup" since it already contains those differences compared to the Ford/GM versions. My guess is that the name was changed from a CP3 to a "CP-ISB21" solely to avoid any potential legal challenges. In the event something ever goes to a judge and they start dancing around the fact it has different parts and thus is technically a different pump.

 

[Epsilon Plus]

What would they be dancing around? Call it whatever you want, doesn't change the fact that they had a bad pump in 1.75 years worth of production, a revision for .25, and a whatchamacallit different design 2 years after their accused F up.

Nothing will probably happen in the courts because companies *usually* skate by on these things, but I would say if something WAS to happen, Ram has the biggest dagger against them of the big 3 because of all their hurried changes/fixes in such a short amount of time. If their phantom "service solution" is a retrofit and not some BS warranty extension that will show the courts they took care of people as soon as they had the problem sorted.


Speaking of, the Internet is going to explode if RamCares comes back in here with a warranty extension instead of a swap. I would call in sick on announcement day if I was on that team

 

[UglyViking]

What would they be dancing around? Call it whatever you want, doesn't change the fact that they had a bad pump in 1.75 years worth of production, a revision for .25, and a whatchamacallit different design 2 years after their accused F up.

I think my comment doesn't disagree with yours. Legal teams focus on perception, not reality. The law isn't about right and wrong, it's about what you can convince a judge/jury of. My point on the naming convention was that it's another item to back them up in the event this goes to court. It's a bit concerning that they chose to give it a unique name designation as that sort of points against a retrofit for CP4 owners.

Very eager to hear what @RamCares has to share. I'm still hopeful that I'm looking at things through a pessimistic lens and they take care of us CP4 owners.