Hey guys, Jake with 8020 Media here, bringing you a video today on the
6.7-liter Cummins Turbo diesel engine. The 6.7 Cummins was launched
midway through 2007 after Dodge retired the 5.9 liter
24 valve due to emissions regulations. A big change between the 5.9 and
the 6.7 was a switch to a variable geometry turbo, which as we'll cover later on has been a
rather problematic turbocharger for the 6.7 Cummins. Power production
is varied from year to year, but the 6.7 Cummins was the first
one to hit the 1000 torque mark, and now for 2023 is producing 1075 pound feet of torque. The 6.7 Cummins is a little bit
different from its competitors, in the 6.7 power stroke
and the 6.6-liter Duramax, in that the Cummins is an inline six
rather than a traditional V8 design. Now throughout its nearly
15 years of production, it's gone through a number of revisions
with a few changes in 2013 as well as in 2019. So we're gonna do our best to distinguish
the problems between the years and the different generations.
However, there are a couple problems that are
coming across all of the different years and different generations of the engine. The first problem is with the DPF system, which is the diesel particulate
filter for 2007.5 until 2012, the 6.7 Cummins didn't use DEF
fluid because it didn't have an SCR system. Because it didn't use DEF fluid, it actually caused the engine
to run a little bit more rich, which causes more soot buildup. And that combined with a bad regeneration strategy caused excessive buildup
within the DPF system and ultimately would lead to a clogged DPF filter. Now, this is less common in 2013
plus models because SCR as well as DEF were added. However, you know, a clogged DPF is common across
pretty much any modern diesel engine. And so while it is less
common in 2013 plus models, it's not necessarily uncommon.
When the DPF gets clogged, it typically causes a loss of power and
it can send the car into low-power mode. Due to the frequency of this problem, it's really common to see owners
deleting the DPF system as well as the EGR system.
However, we won't go into that since that is
something that's illegal to do and the EPA is starting to crack down on. So
while that is a common option, we're gonna go ahead and leave it at that. The second most common problem
is with the turbocharger. Earlier model 6.7s are most prone
to this and there are a couple different things that
plague the turbocharger, and
that's leaking oil seals, worn bearings, sticking VGT components, as well as compressor or
turbine wheel damage. So, overall the turbocharges on the
6.7 Cummins tend to be rather problematic. With that being said, you typically don't see problems
until after the 100,000 to 125,000 mile mark and so
they tend to be relatively reliable up until that point. Again, this is most common on the earlier models, but turbochargers are extremely
high stress components. On the 6.7, the turbine wheel can spin at over
100,000 RPMs and so there's just a lot of stress that are
put on these components, which is why it tends to
fail as frequently as it
does. With that being said, whenever it does fail, one of the common things to do is
to put a larger turbocharger in it. By putting a larger turbocharger in there
and running it at kind of stock power levels, you're essentially reducing stress on
the turbo and requiring it to not work as hard, which can increase the reliability
of it. And so if it does fail, we'd recommend looking into some
OEM plus type replacements for it. A third common problem is head
gasket failure and now we don't believe that this is necessarily as
common as it's been made out to be on the internet, but the head gasket does fail a lot
more frequently than it does on the 5.9 Cummins, which is why this makes
our list. When you look at the 6.7, especially the newer ones, they're producing over a 1,000 feet
pound of torque and you know the cylinders operate under very high
pressures which can lead to head gasket failure. The most telltale symptom of
head gasket failure is white smoke coming out of the exhaust that typically
has like a sweet smell to it. You'll also might notice oil mixed
with coolant or coolant mixed with oil and you'll typically see a lot of
overheating when you do have head gasket failure as well. There are
some kits that prevent this. You can go ahead and use a heavier
duty gasket as well as ARP head studs. However, this kit or kits like
this typically cost about $1,800 to $2,000. And so using a kit like that's most common
if your head gasket is already failed or if you are modifying
the 6.7 to produce a good bit more power than stock. A gasket
itself is pretty inexpensive. So the majority of the cost to repair
this is a is labor and so you're looking about $1,000 to $1,500 to fix this issue.
If you want to go ahead and put an upgraded head gasket kit on
it and use upgraded studs, you're probably looking at
the $3,000 to $3,500 mark. And so something to be aware of that
preventing this issue from happening again is relatively expensive. A fourth problem is with fuel dilution. So the 6.7 Cummins doesn't use a
seventh fuel injector to inject fuel into the exhaust stream
for DPF and regeneration cycles. Because it doesn't
use a seventh injector, it can cause some fuel to stick to the
cylinder walls as it's sprayed out during the exhaust stroke. And this
can cause it to mix with oil, which essentially causes dilution
within the oil and can lead to excessive wear on the internal
components of the engine. Dodge claims that 5% dilution is
within normal ranges, however, the 6.7s are known to experience a little
bit of excess dilution and so it is a good idea to get an oil
analysis done on your 6.7 from time to time, just to make sure you are keeping
it within a normal level of dilution.
Otherwise, it can lead to a lot of additional
wear on internal components and cause the engine to fail more quickly
than it would otherwise. There are some ways to prevent this: one is by letting your engine warm up
before you do any heavy driving with it or heavy towing, and then another
is to prevent excessive idling. The fifth common problem on
the 6.7 Cummins is with the
emission systems as well and more specifically with the EGR cooler. EGR cooler failure is extremely common
across every modern diesel engine out there, including the Ford
and the GM engines as well. And so this is a common problem, it can be somewhat expensive
to replace. That being said, if you're looking at choosing
a 6.7 Cummins over the
PowerStroke or the Duramax, those engines as well
suffer from EGR issues, DPF issues and so on.
And so this is a common problem, but it's common across all diesel engines.
Like I mentioned with the DPF system, it's common to delete that system.
Usually when you delete the DPF system, you also delete EGR as well, which prevents any issues
with the EGR cooler failing. And so that is a common
route to go just due to how common of a problem it is to
have EGR related issues, dpf, SCR and DEF related issues
with the 6.7 Cummins. So that wraps it up with our video
on common problems with the 6.7. Overall, we give it an
average reliability rating. The majority of the issues with it
are with the emission systems or stem from the emission systems. And
like I continue to say, you know, this isn't unforeseen in
the other engines out there, so this engine is certainly less reliable
than the 5.9 and the other kind of pre-emissions diesels, but
it's probably, you know, average for the diesels being produced
today. I know everyone tends to have a preference between GM and
Ford and Dodge. I drive a Ford, but if you ask me right now who's
producing the best diesel engine on the market, it'd probably be the Duramax L5P. Now before people come for my
head and the comments on that one, that engine as well does have a
number of common problems with it, which we've discussed in a separate video, but that's just my opinion on what I think
the strongest engine in the market is right now. The 6.7 Cummins still should
be good to last 250,000 plus miles with proper maintenance.
And so don't get me wrong, there are plenty of very
reliable 6.7s out there. I would just note that the general
theme is that the newer engines are more reliable than the older engines. And so if you're looking at
some of the earlier model 6.7s, especially ones that are high mileage, just know that you might run into some
issues with turbocharger, head gasket, and the emissions systems.
So generally speaking, newer is better, newer is more reliable, but these problems do tend to plague
the majority of the 6.7s out there. Anyways, guys, that's all we've got
for this video. As you can tell, our table continues to get filled up with
a bunch of different parts here as the rest of our turbo kit came
in for the 135. And so, one of the next up videos will be the
start of our build series for this car right behind me. So give us
a subscribe, like this video, and stay tuned for future videos.
