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Look inside the 25+ redesign engine/block/head
- Thread starter Brutal_HO
- Start date
MacksRam
Active Member
Overall, I feel Dave had more positive comments than negative comments as it relates to the new 2025 Cummins engine.
People have been saying the head/valves/rocker arms/lifters, etc on the 2025 are the SAME as the 2019-2024 models--Dave proved there are differences--prayerfully these differences are going to result in a more solid platform (especially when Ram gets the "electrical" issues resolved).
The video kept "buffering" for me, so it was difficult to watch.
I've not really seen anyone saying the 25+ engine redesign has the same heads, etc. that were used on the 19-24 CGI. Must just be Bookface fools.
Early on before release, there were many that saw the leaked photos, several of which myself and a few others had early access to, claiming the head was aluminum. That was a big LOL. The valve cover riser is aluminum.
The hydraulic lifters remain, and use the same part number. That doesn't mean they are identical to earlier lifters, there are different suppliers. In the engine he tore down, I saw that they did not have any oil control(?) grooves cut in them.
I think there's merit to the theory proffered by many including Dave that the CGI block has too much flex and the lifters are "fretting" due to this.
LuckyK
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I saw that video too. Agree - mostly positive. But he was weighing a 2026. And seemed to imply that the new block and intake started in 26. I’m sure someone has ‘schooled’ him by now that it actually started in 25. He’s usually pretty good about admitting when he misspeaks. Regardless, really enjoyed watching him go through it. I wish he would have put the rocker mounts on a flat surface to see if any gaps appeared.
CdnHO
Well-Known Member
Did I hear it right? My hearing is pretty bad. Earlier engines only had a camshaft bearing at each end?? I may have misinterpreted the video, but found it hard to believe that the camshaft would not have more bearing support than that. Of course it has been almost 60 years since I was in the trade and things have changed. LOL. The 2025/6 now has a bearing between each cylinder??
superjoe83
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The flat tappet engines cams had the same number of bearing journals, but they had no bearing inserts, the cam journals rode directly on the block except for the end journals, I believe the old 5.9's only had a bearing on the gear end.
They started putting bearings on all of the journals on the 19+ engines
Those grooves around the upper neck of the lifter body are not oil related. They are tooling marks intentionally placed there to identify which manufacturer (or specifically which production line) each lifter body was manufactured by. There are, or at least were, up to 5 different “versions” of the lifter body at one point. Pretty sure that’s been narrowed down to just a few now. It isn’t uncommon to pull all 12 lifters out of a factory engine and find a mix’n match set from different suppliers.
Some suppliers have a higher failure rate than others, depending on when they were manufactured.
The same supplier that manufactured the lifter bodies for 24 and older, are still supplying lifter bodies for the newer engines 25+.
They did, however, change the manufacturer for the roller that attaches to the lifter body.
MacksRam
Active Member
mbarber84,
Good info--thanks.
This sentence caught my attention: "They did, however, change the manufacturer for the roller that attaches to the lifter body."
Do you have any more details on this?
Right, and I now remember seeing that info. The (elderly) mind is a terrible thing to waste.
That’s a reality that becomes more and more clear to me each day!Right, and I now remember seeing that info. The (elderly) mind is a terrible thing to waste.
Both the lifter bodies and the rollers that attach to them can cause premature lifter failure.
The chief mode of failure, when referring to the lifter body as the culprit, is the roller axle bore. If that bore is drilled / machined on any angle other than parallel to the cam shaft, it causes the roller to sit at an odd angle to the cam lobe. When this occurs inside the engine, it creates increased stresses on one side of the roller, and a twisting force as the roller runs up the cam lobe. What you end up with is premature wear on one side of the roller, eventually leading to surface spalling. It can also cause the lifter to twist axially in its bore, further increasing the failure rate. As the wear continues, it will eventually start to cause the roller to seize or develop a flat spot, at which point the failure accelerates rapidly.
The chief mode of failure, when referring to the roller, is its profile across the width of it. Some of the rollers are manufactured poorly, where one side of it has a large diameter (or smaller diameter) than the other. This created a “tapered” roller, which increases stresses on one side more than the other. From there, the failure is very similar in nature to what i described above for the lifter body related failure.
In either case you end up with stresses and surface wear that is not uniform, but rather concentrated on one side or the other.
You'd think the fact that lifter rollers need to be round and not tapered, and that the roller needs to run perfectly parallel to the camshaft would be a given. If deficiencies in these areas are what was causing lifter/cam failure then it sounds like they had a design/tolerance/quality issue?
As for some of the other changes, seems mostly positive, I just wish they had fixed the grid heater issue instead of going with glow plugs. And I hope that rear structure gasket works out. I think maybe it's had its challenges on some other Cummins engines, like oil leaks.
As for some of the other changes, seems mostly positive, I just wish they had fixed the grid heater issue instead of going with glow plugs. And I hope that rear structure gasket works out. I think maybe it's had its challenges on some other Cummins engines, like oil leaks.
Oh it’s definitely a given.
These were 100% quality control / manufacturing issues. Not design issues.
MacksRam
Active Member
Good discussion guys...
In addition to the quality control/manufacturing issues, I think you have to add Brutal Ho comment "I think there's merit to the theory proffered by many including Dave that the CGI block has too much flex and the lifters are "fretting" due to this."
To summarize--when you consider the of roller/roller axle bore quality control/manufacturing issues AND potentially "CGI block flex" (I say potentially because this is probably theory) you have a bad combination. Again, hopefully by Ram/Cummins changing Lifter/Roller suppliers and switching to a Cast Iron block--hopefully these problems are resolved or minimized. Feel free to step in and correct me or add to my thinking here....
Fretting and the block “flexing” has been noted in the past, especially by several well known performance houses, including Choate.
This video (Click Here For YouTube Video) is a good one to watch. The guys from Choate discuss this starting at the 50:00 min mark onward.