This right here is a hydraulic roller lifter out of a 6.7 L cumin diesel engine and today we’re going to take a look at why this is potentially. Failing welcome back I’m Alex, and today we’re talking about the old cumin engine in these Ram. Hd pickup trucks and maybe I’ll eat some of my own words. In the past, I’ve said that these inline six diesel engines are the best diesel pickup truck engine.
You can get because it’s a commercial grade engine in a dare I say, consumer truck, so these engines come already over engineered because they are meant for a commercial use, but maybe that’s no longer the case before we get too ahead of ourselves. We need to step back to 2019 and that’s when RAM and cumin introduced a brand new generation of the 6.7 L cumin diesel engine in these HD Ram pickup trucks, bringing a number of upgrades like a compact, graphite iron block and d d d, hydraulic roller lifters. Before 2019 traditionally used what’s called a flat ta, it style, lifter um, it’s very simple and therefore pretty darn reliable. It’S just a single piece of metal.
Here’S your good old push rod and, as the cam L comes around, pushes up on the flat tap it lifter pushes up that push rod and the selected valve opens up, and while cumin has been using this style of flat, taid lifter since the debut of the 59 in the 80s – and you might ask yourself: why fix what ain’t broke? Why go to a hydraulic roller lifter and apparently it’s all due to maintenance. You see a valve train needs a specific amount of backlash or play Because as metal heats up and expands, there needs to be room for a little bit of expansion between the components of the valve train and from time to time you have to adjust that play Or backlash, and that is the maintenance that cumin is avoiding by using hydraulic roller lifters instead of solid flat ta it here’s my friend Adam on an ISX 15 L commin engine and just listen to this. So what you’re hearing right there is valve lash and you don’t really need much like on a Detroit Diesel, which I work on a lot um. The intake valves at like 16 thou of valve lash.
So it’s not a lot, but you need to make sure it is inspect for a proper running engine and that’s why we need to inspect and adjust the valve lash on the older 6.7 L cummin to make sure it is in Spec. Now the beauty of a hydraulic lifter is that it uses pressurized engine oil and there’s a spring and a plunger in here, and it sets the proper valve adjustment every time the engine starts. So, there’s no need to worry about valve adjustments down the road um, as you guys can see here. That’S where the oil goes in and once this this lifter is full.
It should set the valve train to the correct spec, so you’re going to save on some maintenance with these hydraulic roller lifters. But how much maintenance are you actually going to save well with the older sty Commons, with the older style flat ta? It lifters Commons recommends doing a valve adjustment every 150,000 mil. So in my eyes the average truck owner might have to do a valve adjustment. Two three maybe four times in the life of the engine, which I don’t think that’s – that much maintenance or maintenance cost Savings.
In my opinion, I would much much rather have the simpler, more reliable flat taet style design that cumins has been using for decades than potentially have a less reliable hydraulic roller lifter. That might save me a little bit money on maintenance costs. Now, here’s where the water gets a little bit murky for me, so this is a true commercial grade: 6.7 L, cummins or ISB coming in a good old school bus here, and this is a 2024 engine and being it a brand new engine, you would think that It comes with hydraulic, lifters, right right, wrong. This engine comes with flat, taet style lifters, and I know that for an absolute fact, because I ordered this specific flat.
Taet lifter, with this serial number of engine came out of Montreal for this specific engine. So, despite this engine being 2024, it still uses flat, ta it style lifters. So to me, that’s everything you kind of need to know because on the commercial side of these engines, reliability is extremely important to these manufacturers, especially cummin, and they opted to go for the more traditional tried, andrue flat ta it lifter and did not put those new Hydraulic roller lifters in their commercial engines, for probably a good reason, what’s also kind of neat, is behind the 67. They outfitted a good old commercial, great Allison Transmission, not a bad combo. So with all that being said, what exactly is causing these hydraulic roller lifters to fail in the 67 cumin and well?
Sadly, there just really isn’t a concrete answer. Just yet there’s a number of theories on the internet like there always is, and the first one and probably the most popular theory is that people are running the wrong weight of oil. Anyone with a fifth gen or a 2019 plus Ram HD truck with a 6 cummin. You cannot run 15 w4e oil sounds a little countered because that’s what cumin has ran since the80s, but earlier in 2020, I think. Maybe 2021 cumins released a technical service.
Bullettin saying directly that if you run 15 w40 in these newer fifth gen cumin engines, it will directly lead to valve train damage. Now this does make some sense on both sides of the spectrum. So, first of all running thicker oil. You could potentially be having more oil pressure in the engine and well again, these run on engine oil pressure. So, with more engine oil pressure acting against the spring inside here, you might push this plunger out a little bit too far and incorrectly set your valve train adjustment which could lead to damage on the flip side of that with thicker oil.
It’S going to take more time to actually fill this lifter, especially in cold conditions. The valve train component are usually the last components to get oil flow when the engine starts up. First, is the engine bearings, obviously the most critical, so it might take a little while for this lifter to fill up – and it’s just going to be smashed around on the cam shaft until it does, which again could cause damage. Thinner oil, especially in colder climates, will be able to fill this lifter much quickly or much more quicker and therefore you’re not going to get that same sort of Cam Shaft smashing going on during a startup condition. So those are the two reasons why I could see that thicker oil might not be very good for this valve.
Train humon recommends you use 10W30 or in colder climates like in Canada. Here you run full synthetic 5 w40 Oil, and you know these. These commin engines are producing a ton of power and you would like to be able to run that thicker more protective oil than the thinner oil that cumin is recommending. But you know the engine is set up. The valve train is set up to run that thinner oil, so you kind of have to do it now before you freak out of Cummins Detroit Diesel, the engines that I work on, they make fantastic diesel engines.
They’Ve been running 10W30 in their engines for years, and it just seems like that’s the way manufacturers are going to what lower emissions. Unfortunately, it seems like 10w30 um. It helps manufacturers to lower first fuel econom or raise fuel economy, but most importantly, secondly, lower emissions and I feel like humm, is probably no different there. Unfortunately, I don’t think that’s the full story, because there have been a number of reports of engines that run the correct weight of oil still having lifter failures, and I don’t argue that running the wrong weight of oil could potentially put more wear on these little puppies. Here but I don’t think it’s the whole story.
Another speculation into these lifter failures is that the oil change interval on these cumin engines is just too long, and I find that odd, because the oil change intervals haven’t really change the 2019 plus commin engines. Um commin recommends changing their oil or its oil at 15,000, mi or 500 um hours of runtime, the 2018 and Below 67 Commons have a recommended oil change interval, time of 15,000 M and 500 hours of runtime. Additionally, once again again on the commercial side of the 67 cumin, this engine can apparently go 30,000 Mi between oil changes or 1,000 hours of operation, and it’s not dropping lifters or cam shafts. Despite that extended oil change interval now granted, we do have a 19 CT oil pan versus a 12 court on the pickup truck. So keep that in mind.
Lastly, there’s even reports of Commons engines dropping lifters below, like 10,000 M of runtime, so to me hearing that, yes, oil has a massive role to play on any component of the engine, especially a hydraulic roller lifter. But if I had to guess it seems like there might be a Metallurgy problem, a bad batch of lifters or even a design problem with the lifters themselves. It does seem for whatever reason like the 2022 model year, trucks seem to have a lot of lifter failures happening in what was before 2022, the good old pandemic, where quality control AC Ross, it seemed all manufacturers took a pretty dramatic dip so again, potentially just a Bad batch of lifters, but at the end of the day I’m just some dummy on the internet and cumin has kept a pretty tight lip on this lifter issue, but I’m sure eventually it will come out at some point. For me, I think the real story is the fact that cumins felt like it was beneficial to the consumer to ditch this tried and true, reliable, simple flat t pet style lifter for the more complex, less reliable, um hydraulic roller lifter. I don’t think I’m alone saying that I would rather have a little bit more maintenance, a little bit more maintenance cost on my engine, knowing that it would be more reliable, I think the beauty and why people love the 67 cumin, as well as the 59 cumin Engines is because they were commercial grade engines over engineered engines for a pickup truck application.
It resulted in tons of reliability and extremely long longevity of the engines. So, ultimately, it would have been really nice to see, stick towards that commercial side of things and not try and eliminate maintenance for the consumer if that makes sense. Well, this is what a real commercial grade. 6.
7 L engine looks like behind me here.
Let me know what you guys think. Are you concerned about these lifters always love hearing what you guys have to say? But if you did like the video, don’t forget to leave that thumbs up and if you like, cool stuffff, like this, don’t forget to subscribe, because we will be keeping you updated on this lifter issue. But as always enough of me, we’ll see you in the next freaking video
