Why Inline Six Engines are Easier to Rebuild in Semi Trucks 

This loop was on point though I was watching a whole different video

I6 is my favorite engine pattern

I wish more production cars used inline 6 engines nowadays.

Inline 6 is my favorite engine configuration. Perfect balance, flat torque curve, mechanically simple.

The inline 6 Cummins is beast

"Here at Subaru, we know you'll need a rebuild soon, and took that into consideration..."

as a guy with a ‘06 Ram with a 5.9 Cummins, the engine is a giant lego brick.

When I worked in a city transit bus shop we could do a full engine rebuild with the block in the bus. Called an “In-frame rebuild”. It would take us about 32 hours, or 4 shifts.

An inline 6 is just a great engine.

This is why when I upgraded to a diesel engine truck, I went with a Ram 5.9l cummins. When you pull heads off of an inline engine, and look at the cylinder walls, the cross hatching still is clearly present. I've seen the old 4.0 inline 6s in the jeeps with 200k miles on them still look like freshly machined cylinder walls. The straight up and down pattern wears way less than the rod angle of V pattern engines.

Back in the day I did so many in frame rebuilds. Some even worked afterwards.

European trucks using V8s: “I’m gonna pretend I didn’t hear that”

The actual difference in rebuilding a “semi-truck” (class 8 truck) engine compared to a pickup is that the large diesel engines used in big trucks use a separate removable liner for the cylinder where light duty diesels and gasoline engines (even the fabled 5.9 / 6.7 Cummins) are simple parent bore designs where the piston rides in a bore in the block itself and the cylinder wall is the cast iron of the block itself, meaning that once the bore is worn enough to warrant a rebuild or a piston gets got and causes scoring the block has to be removed and over-bored on a mill regardless of whether it’s a V or inline design. That said up until a little over 30 years ago there were V engines offered in HD trucks, the last of them being the fairly popular 92 series Detroit diesels and the 3408 Caterpillar which is far less common. These engines used liners and could be “rebuilt” without removing the block from the chassis (an “in-frame” rebuild) and really weren’t significantly more difficult to rebuild than an inline engine, in some cases they were even slightly easier to work on in trucks with short hoods and limited space in the engine bay. The in-line 6 engine design ultimately won out though once length laws were reduced and stricter emissions standards were implemented, their advantages in longevity and ease of packaging ultimately outweighed the advantages of the V8’s, which were mostly related to size where space was limited and weight to an extent.

Inline 6s in my experience can get nearly the same type of fuel economy too I have a turbo 4 now but I used to have a non turbo inline 6 and it would average 30 mpg which is saying something cause I’m definitely not all highway miles

Okay okay you convinced me. I must put a semi truck’s inline 6 in a Miata

“The frame rails really aren’t in the way of anything.” Paccar MX has joined the chat.

Plot twist…still charge the same labor regardless of engien configuration

straight six also has less internal friction, it uses less fuel.

I love inline 6s

I will never sell my 96 f150 straight 6. Great torque.

1million 450 thousand miles on my Detroit series 60 run the hell out of it everyday .

My boss in Texas back in the 80s had a KTA 600 Cummins . It was a beast . 100 hp per cylinder .

Dodge Cummins and the famous firewall and stamped pushrod clearance holes has entered the chat for in frames lol

No matter who made them, they are all pretty much good.

I see you N14 Cummins ❤

BMW's slant 6 header bolts joined the chat 🤣

My first truck was a 1969 Chevy with a 250 straight 6 and a 3 on the tree. Super easy to climb inside and sit on the fender. My Dad also had a Dodge with the 225, also very reliable. I don’t recall any inline 6 that were not reliable

I have 235 straight 6 in my 1950 truck. Amazing engine, you can’t kill them

Backyard Miata looking around nervously

Well the fact that it has removable liners is the biggest factor that allows for inframe to be done

I was a Jaguar tech fpr many years, i had the pleasure of sleeving a 4.2 litre 6 cylinder that a wrist pin came out and cut a slot in the cylinder wall, didn't have to remove anything but the head and oil pan, got it done in under 8 hours

Doing an in-frame rebuild on a V-8 isn't more time consuming because the frame rails are in the way. It takes more time because there are two more cylinders and the crankcase is crowded with two rods per journal. Two heads on either side makes a difference too.

Mazda just released their CX-60 comes with a 3.3 inline 6 turbo diesel, really smooth and quiet, heaps of torque

Unless it’s a ford 300-6, you gotta lift the engine just to replace the oil pan gasket.

I love an inline six, they' re preferable to me over other configurations. I had a Mercedes-Benz with a seven main bearing M114 inline six, and it was so smooth. I put in new rods, mains and oil pump and drove it three more years after the rod bearings wore out. I did it in-situ. Piece of cake.

I miss my 1980, straight 6, AMC SPRINT, WITH A MANUAL TRANSMISSION!

Love my 258 straight 6 in my jeep. Plenty of torque!!

Depends on the cab we did a head gasket and it was easier to pull the the engine

Scania and the Euro 6 V8 diesel engine have entered the chat

As a Skyline owner i see this as a complete win!

I grew up in an auto repair shop my father owned. We specialized in Nissan/Datsun Z cars which are in line 6s. Rebuilt plenty of L28s in car.

PERFECT ENGINE !!

Picked up a clean 96 Cherokee County with a straight 6 a couple years ago. Absolutely love that thing

Gotta love an inline 6.

I remember being a kid doing this with my pops I remember him putting the pistons or the liner in boiling water before placing them inside the engine

The DD15 in the truck I drive (so far) is a real champ. Love the way it sounds cold early in the morning. It's a bit of a dog up hill (governed) but so far so great. I'd only put a Cummins above these Detroits

That's a great looking block

Amen, just freshened up a 51 gmc. So much easier then other configurations. Appreciate all engines but dang this was super easy.

Each cylinder gets its own head? Wild!

Getting a fresh rebuild. 🎉

For MANY MANY years, Ford Australia had an inline 6 in their main family car, the falcon. Essentially the same block from 1979 to September 2016. I have a 2008 that is a DEDICATED propane engine, FACTORY built to ONLY run on propane. Incredible power in the thing.

I love the Straight 6 300 In my f150. Balanced in all directions

Always loved straight 6 🇬🇧🙏

The I6 is my favorite engine layout

Which is why my mom loves working on newer dd13 engines

That engine is massive, never knew they are that big.

And they sound sick.

Dat ! stress on the middle of overhead cam shaft tho 😂

Amc 242. One of my favorites and sad to say it was discontinued in 2006.

I love straight six engines, have owned 3 different ones ! Nissan rb, jeep, and bmw

That's why my bmw is dope. The inline 6 is the best motor I've had in a sedan

Ive always loved the inline 6, ever since i learned what kind of insane power people get out of the skyline gtr L6 engines ive wanted to build a car with an inline 6

In my past job , we rebuilt a Scania 113 engine on 3 different occasions without removing the block. It was so simple and in 24hs the trucks where out. So yeah , really nice to work on .

Online 4 is great too, still easy to pull an engine and make sure you do it correctly aka sending out to be bored over and honed.

Never thought about it but it is so very true

holy crap that’s a massive enginr

I love working on inline 6 engines so much more then any V8; my L28 in my 280z is so easy to work on compared to the El Camino I was daily driving

Scania with the V12 "I got 2 of dem I6es!"

I wish that fit in my 2021 Golf. I'll just stick to my 1.4L... T 😬👍

Personal truck ill always have a power stroke, they’re more fun IMO and about the same reliability as a Cummins in my experience, however if I’m gonna have a dedicated tow pig it’s gonna have to be a DT360/466 or a Cummins, it’s better that way because like you said, when something breaks it’s easy to get to

Love my inline 6 Barras, balance.

Love the 500 Detroit

A good engine builder rotates the crankshaft after installing a piston.

We still pull the ISC and X15 Cummins motors out along with the transmission in our kenworth trucks just so we can inspect the area that the motor mounts to for rust damage

I wish they put it in more cars

i love the I6

That's why barra on top

Yep! You can literally pull a bad sleeve and replace it, check everything with a machine level and have it back together Monday morning!

You do have more block twist and crank flex when running high horse power due to them being longer which is why top fuel cars use v8 motors

What I was going to say was by in large covered in the video here. With the only downside to the in-line configuration is physical size for length and height. But even that isn't that much of a issue if comparing these to the V blocks found in Europe. Even the 'small' v6 there is nearly as large as the I6 here and is certainly wider. What I miss having, is the I6 as an engine option for pickup trucks and some sedans. Well save for BMW, they still rock a I6. Nissan makes a nice one, in gas and diesel but doesn't offer it for the north American market, at least one that isn't a joint venture. Toyota is the same, Isuzu paired with Nissan and is badged as 'Duramax'.

Oh boy the Bore is huge like I feel like my son can fall in lol love engines

I love how an online design is both the oldest and best engine design out there

Inline 6 is the go to standard engine of "any" size. Simple , inherently balanced and ruggedly tough is the main selling point of this design. AND scaling it to any size still gives you the same benefit as others on the family. For an even more compact and powerful AF, you have the V 12. The same principle as the inline 6. Each bank is balanced like an inline 6 but sharing a common crankshaft and crank pin.

Now I understand why it is so strong with high and low gear, with turbo.

inherent balance of inline 6 saves a lot of time effort and money, while still producing great power

The gas variant can have 2 or 3 cylinders lose piston rings, get one home and still idle relatively smooth.

Funnily enough the first big rig i ever saw had a v12 in it.

I still love my 3408 Cats.

I just learned something wow😂

Great video

I work on Detroit’s at work and they definitely are a bit easier to work on inside the engine bay

Depends on the vehicle. But on average it is true

As a bmw guy I love tf outta a I6

The Mopar 225 Slant 6 and Ford 300 straight 6 or two of the best I6 engines ever built. Both million mile capable.

V8 macks are pretty cool

Only downside to i6 I can think of is the heat displacement into the manifold causing cylinder 1 or 6 to overheat, potentially causing broken rings,cracked heads, etc. Not saying you can't overcome this with a better designed header, but some i6 engines have this problem. Seen it in common rail cummins and bmw engines

I6 perfect* balance baby!!!

Ford 300, Cummins 5.9 6.7, and now the Duramax 3000! 💪

I got an odd engine. Good ol I5 It’s American made too. Chevy Colorado, GMC Canyon, and Hummer H3 came with a I5 engine option. I have a canyon, and love it. It’s odd enough to stand out, but some of those H engines or overly massive.

Oh the shop will charge the same anyways.