Was contemplating a 2025 6.7 Cummins... Nope!

[flan]

Some pretty good fuel system info in this q/a. They mention the rollers are pinned and the system psi is up to 39k psi with the cp8.

FIRST REVIEW: 2025 CUMMINS ENGINE

FIRST REVIEW: 2025 CUMMINS ENGINE It was only two weeks ago that the folks at Ram gave members of the press the first ride-and-drive opportunity at...

www.turbodieselregister.com

 

[H3LZSN1P3R]

Some pretty good fuel system info in this q/a. They mention the rollers are pinned and the system psi is up to 39k psi with the cp8.

FIRST REVIEW: 2025 CUMMINS ENGINE

FIRST REVIEW: 2025 CUMMINS ENGINE It was only two weeks ago that the folks at Ram gave members of the press the first ride-and-drive opportunity at...

www.turbodieselregister.com

Also the lube circuit is separate so no filling the rail and injectors with glitter

 

[Brutal_HO]

Confirms the 7th injector for DPF

 

[aaron_huber]

Confirms the 7th injector for DPF

Finally, regen can't cause fuel dilution any more since the extra fuel isn't going into the cylinders. Excessive regen can still reduce your mileage but at least it won't destroy your engine.

 

[mbarber84]

I’ve spoken to several people both at Cummins and Ram on the fuel pump. Completely independent people from each other. Both have passionately assured me that the amount of rigorous pump testing they have conducted on the new CP8 has been substantial. Both of them mentioned the pump killer test, and both of them said this new pump utterly shocked them at how well it endured, despite conditions that were well beyond anything they will ever see in normal, or even extreme operating conditions within these trucks. I’ll admit I was less than thrilled when I saw the new pump. However, after speaking with the contacts, I have a lot more faith in this new pump to perform well. Both parties are well aware of the pitfalls and follies of the previous pump, and neither one wanted a repeat of that debacle.

 

[Brutal_HO]

<snip>

The primary issue I was looking to Ram/Cummins to resolve once and for all was the continual slow motion train wreck that is the high pressure fuel systems on these trucks. Bosch actually makes some interesting high pressure pumps, I've seen with my own eyes the CP9 on large stationary Onan generators. They very rarely fail, they are internally lubricated with engine oil, like the old school P pump engines. Most of the time the high pressure discharge line breaks from vibration and fills the gen enclosure with perfectly atomized fuel mist... But the pump is solid.

From looking at the pictures, the Bosch "CP8" is our old friend with a new name - the CP4, which has come back to haunt us yet again. I'll give it to the sales folks over at Bosch, they really know how to close a deal! Nevermind the fact that Stellantis probably paid out millions to recall all the CP4 trucks from 2019-2022. Perhaps Bosch reimbursed them. Doesn't matter, because judging by the pictures, the "CP8" very much looks like a CP4.

I'll admit I have no idea if the internals look the same. I'm an armchair engineer here... Perhaps they finally pinned the followers so they don't rotate. GM paid out lots over the CP4 issue in the LML duramax trucks - and learned their lesson, they went with Denso as the supplier on the L5P (and the LM2 3.0 duramax) Ford has done an incredible job of landing every failure on the owner's lap over "lack of maintenance" or "buying junk fuel"

I won't be buying one. I hope for the collective sake of all the good people on this forum, and the rest of the folks out there in the world dropping hard earned cash on these $100k mortgage payments on wheels that the new and improved fuel system, really is new and improved.

Those Who Do Not Learn From The Past Are Damned To Repeat It.

Assuming you've had a chance to review this article, has your opinion changed?

FIRST REVIEW: 2025 CUMMINS ENGINE

FIRST REVIEW: 2025 CUMMINS ENGINE It was only two weeks ago that the folks at Ram gave members of the press the first ride-and-drive opportunity at...

www.turbodieselregister.com

 

[jharp]

I'd say I am 'cautiously optimistic' at this point... I appreciate the efforts that went into discussing these and other issues with engineers at Cummins.

 

[jake2544]

I spent the last year waiting with bated breath to see what upgrades the 2025 Ram/Cummins combo would have. I, like others, was excited to see the 8 speed transmission upgrade. Like Ford/GM, the 'guts' of the new 8 speed are most likely similar between the entire platform - GM/Ford has the ten speed, which has the same general architecture regardless of vehicle (a Tahoe has the same valve body as a Duramax 3500, as one example.) The ZF 8 speed is really a good transmission... So I have hope there. The 2025 Cummins power bump is also fantastic.

The primary issue I was looking to Ram/Cummins to resolve once and for all was the continual slow motion train wreck that is the high pressure fuel systems on these trucks. Bosch actually makes some interesting high pressure pumps, I've seen with my own eyes the CP9 on large stationary Onan generators. They very rarely fail, they are internally lubricated with engine oil, like the old school P pump engines. Most of the time the high pressure discharge line breaks from vibration and fills the gen enclosure with perfectly atomized fuel mist... But the pump is solid.

From looking at the pictures, the Bosch "CP8" is our old friend with a new name - the CP4, which has come back to haunt us yet again. I'll give it to the sales folks over at Bosch, they really know how to close a deal! Nevermind the fact that Stellantis probably paid out millions to recall all the CP4 trucks from 2019-2022. Perhaps Bosch reimbursed them. Doesn't matter, because judging by the pictures, the "CP8" very much looks like a CP4.

I'll admit I have no idea if the internals look the same. I'm an armchair engineer here... Perhaps they finally pinned the followers so they don't rotate. GM paid out lots over the CP4 issue in the LML duramax trucks - and learned their lesson, they went with Denso as the supplier on the L5P (and the LM2 3.0 duramax) Ford has done an incredible job of landing every failure on the owner's lap over "lack of maintenance" or "buying junk fuel"

I won't be buying one. I hope for the collective sake of all the good people on this forum, and the rest of the folks out there in the world dropping hard earned cash on these $100k mortgage payments on wheels that the new and improved fuel system, really is new and improved.

Those Who Do Not Learn From The Past Are Damned To Repeat It.

I feel the same way as you do. Very excited for the ZF 8 speed but then was deflated by the new pump. I already took a huge hit on my 2019 FULLY loaded Laramie that I sold as soon as problems started with the pump.I was so worried that the 19-20 would be a red headed step child truck with all of the plagued pump problems that I sold the truck. Then the recall came, trucks that were down spent months at the dealers waiting for parts. Then there’s also the worry that even after the repairs or pump replacement that there could be some long term problems down the road. As much as I wanted a 25 for the same reasons as you, I won’t even consider it now. I’ll definitely be waiting to see how the new pump does over the next two years anyway. So far I have 28k problem free miles on my 22 so I have some time.

 

[GirchyGirchy]

Saw a video a while back where ram was pointing out all the improvements to the new 6.7 engine. He stated their engineers performed ( a kill the pump tests) the newer CP4 passed it fine but said their new CP8 totally crushed it. Made me feel like they did address the past pump issue. This along with the new tranny heavy duty pistons and easier service ability is why I pulled the trigger on a 4500... fingers crossed

I heard the CP8 failed as well - but so has every other pump they've run. Supposedly the point of the test is to destroy the pump, but see how long it takes to get there.

The order of failure I heard was CP4 first (anyone surprised by this), CP3, then CP8. Which is good.

As for the pressures delivered by the CP3 vs CP4, I also heard that there were changes to the CP3 that weren't available when we spec'd the CP4 for 2019.

 

[gimmie11s]

Id bet money it is the updated CP4 in the Ford Super Duty with pinned pistons that Ford rolled out sometime around 2020-2022.

Problem is Ford's Super Duty is still eating CP4's, to this day, even after the "updated" pinned piston CP4.

Here's to hoping Im completely wrong!

 

[Brutal_HO]

Id bet money it is the updated CP4 in the Ford Super Duty with pinned pistons that Ford rolled out sometime around 2020-2022.

Problem is Ford's Super Duty is still eating CP4's, to this day, even after the "updated" pinned piston CP4.

Here's to hoping Im completely wrong!

Did you read the article?

It's obviously a newly redesigned pump. There's a separate lubrication circuit. Ford's CP4 doesn't have that.

Pinned roller-tappet, flat tappets, separate lube circuit. CP8.

 

[H3LZSN1P3R]

Did you read the article?

It's obviously a newly redesigned pump. There's a separate lubrication circuit. Ford's CP4 doesn't have that.

Pinned, flat tappets, separate lube circuit. CP8.

Sounds like a beast of a pump!

 

[Great White North Eh]

Ya might be a gooder …but all that rework on the internals and then make to outside so familiar? It’s like watching Chucky when you’re eight …that image is burnt into yer brain. One flash of that image and it all comes flooding back.

 

[GirchyGirchy]

Ya might be a gooder …but all that rework on the internals and then make to outside so familiar? It’s like watching Chucky when you’re eight …that image is burnt into yer brain. One flash of that image and it all comes flooding back.

How the hell do you think we felt when we saw it?! PTSD!

 

[gimmie11s]

Did you read the article?

It's obviously a newly redesigned pump. There's a separate lubrication circuit. Ford's CP4 doesn't have that.

Pinned, flat tappets, separate lube circuit. CP8.

I did.

Please explain how a separate lube circuit will prevent failure.

I appreciate your optimism but I have trouble believing Ram gets a pump all to its own while Ford and Chevy continue to suffer through class actions because their pump is not shared with Ram.

 

[mbarber84]

I did.

Please explain how a separate lube circuit will prevent failure.

I appreciate your optimism but I have trouble believing Ram gets a pump all to its own while Ford and Chevy continue to suffer through class actions because their pump is not shared with Ram.

If the plungers are redesigned so that they are pinned, and unable to rotate axially in their bores, and the pump uses an independent lubrication circuit to prevent metallic debris from passing to the rail and injectors, that would pretty much eliminate both of the major modes of failure previously encountered on the CP4. Add to this any other material revisions changes they made, and I’d say the pump has been worked over pretty well. Given the current automotive climate, and the position Stellantis finds themselves in, I don’t believe anyone involved in this trucks release wanted a repeat performance of the past.

 

[Brutal_HO]

I did.

Please explain how a separate lube circuit will prevent failure.

I appreciate your optimism but I have trouble believing Ram gets a pump all to its own while Ford and Chevy continue to suffer through class actions because their pump is not shared with Ram.

Never said it would prevent failure. However, it survived a destructive "killer" test far beyond the venerable CP3.

So what you're saying is RAM/Cummins is lying about the pump design? LOL.

"Ram/Cummins: The Bosch CP8 is a new fuel pump. The roller and shoe design that was in the old pump has been redesigned to a pinned roller-tappet architecture."​

Lastly, GM hasn't used the CP4 for forever, they've been running a Denso pump.

Ya might be a gooder …but all that rework on the internals and then make to outside so familiar? It’s like watching Chucky when you’re eight …that image is burnt into yer brain. One flash of that image and it all comes flooding back.

Familiar, but also not the same.

 

[H3LZSN1P3R]

I did.

Please explain how a separate lube circuit will prevent failure.

I appreciate your optimism but I have trouble believing Ram gets a pump all to its own while Ford and Chevy continue to suffer through class actions because their pump is not shared with Ram.

If you cant understand what the article is saying thats on you but this is not anywhere near the same as a CP4 from all the changes. They literally took all the failure points from the CP4 and eliminated them and then made a separate loop to be sure on the off chance of a failure it only takes out the pump.

Plus the CP4 had a 4% failure rate which is still almost nothing in the big picture

 

[Xflight29]

I spent the last year waiting with bated breath to see what upgrades the 2025 Ram/Cummins combo would have. I, like others, was excited to see the 8 speed transmission upgrade. Like Ford/GM, the 'guts' of the new 8 speed are most likely similar between the entire platform - GM/Ford has the ten speed, which has the same general architecture regardless of vehicle (a Tahoe has the same valve body as a Duramax 3500, as one example.) The ZF 8 speed is really a good transmission... So I have hope there. The 2025 Cummins power bump is also fantastic.

The primary issue I was looking to Ram/Cummins to resolve once and for all was the continual slow motion train wreck that is the high pressure fuel systems on these trucks. Bosch actually makes some interesting high pressure pumps, I've seen with my own eyes the CP9 on large stationary Onan generators. They very rarely fail, they are internally lubricated with engine oil, like the old school P pump engines. Most of the time the high pressure discharge line breaks from vibration and fills the gen enclosure with perfectly atomized fuel mist... But the pump is solid.

From looking at the pictures, the Bosch "CP8" is our old friend with a new name - the CP4, which has come back to haunt us yet again. I'll give it to the sales folks over at Bosch, they really know how to close a deal! Nevermind the fact that Stellantis probably paid out millions to recall all the CP4 trucks from 2019-2022. Perhaps Bosch reimbursed them. Doesn't matter, because judging by the pictures, the "CP8" very much looks like a CP4.

I'll admit I have no idea if the internals look the same. I'm an armchair engineer here... Perhaps they finally pinned the followers so they don't rotate. GM paid out lots over the CP4 issue in the LML duramax trucks - and learned their lesson, they went with Denso as the supplier on the L5P (and the LM2 3.0 duramax) Ford has done an incredible job of landing every failure on the owner's lap over "lack of maintenance" or "buying junk fuel"

I won't be buying one. I hope for the collective sake of all the good people on this forum, and the rest of the folks out there in the world dropping hard earned cash on these $100k mortgage payments on wheels that the new and improved fuel system, really is new and improved.

Those Who Do Not Learn From The Past Are Damned To Repeat I

Why would you think for a minute, after reading the article that Ram and Cummins + Bosh would ever want to re-live that nightmare. They put so much more testing in this pump than any other pump Bosh has ever produced. You go buy looking at the pictures than how the article explained the internals.

 

[SolidAxleorBust]

Honestly its awesome to have so much info on the design flaws, and possible improvements. 6.4 guys would KILL for the same info.