The Making of a Cummins 6.7-liter Diesel Engine

A Tour of Cummins’ Midrange Engine Plant
By G.R. Whale for

Cummins builds diesel engines well beyond 70 liters, so anything below the Class 5 truck market is “light duty” to them. However, the current High Output and standard 6.7-liter ISB inline-six oil burners in Ram’s 2500/3500 heavy-duty pickups and 3500/4500/5500 chassis cabs are built to medium-duty specifications. They’re made at the Columbus Midrange Engine Plant (CMEP) just south of Cummins’ world headquarters in Columbus, Ind. We stopped by to see where this popular truck engine is built.

CMEP was built on more than 400 acres in 1971, and it originally built components such as pistons, connecting rods, pulleys, rocker housings and water pumps. It closed in 1988 to convert to engine production and reopened in 1991, and it has fed Dodge/Ram assembly lines ever since. CMEP has supplied other chassis manufacturers, but that production pales in comparison with the Dodge numbers, and the plant should build engine No. 2 million sometime soon. Total manufacturing and office space totals 587,904 square feet.

Located just off Interstate 65, CMEP is easy to find by road or even by air. The red expanse is the plant’s roof, which doubles as the 500-space parking lot. Since the roof expands and contracts up to 16 inches in temperature extremes, sealing it is a regular maintenance item.

1. When the 6.7 engine block arrives on the assembly side of the building, the freeze plugs and cam bearings are already installed.

This is the closest assembly plant to Cummins HQ, though there is a facility in Columbus that machines heavy-duty blocks and heads and will machine and assemble a new engine currently under development. A polite “no comment” regarding what that engine is.

During our visit, the plant was building about 420 6.7 engines a day on a full-speed first shift and a quarter-speed third shift. The plant can produce substantially more; in 2004, it built 167,622 engines.

CMEP employs about 520 people, most of them on the plant floor and the remainder in the cubes and glass offices. There’s a central courtyard, and from virtually anywhere inside — including from the paint booth — you can see out to the lawns or woods. Occasionally, a wild turkey or deer will scamper by.

The plant has the usual array of loading docks, lube tanks, cafeteria and an auditorium of glass on four sides. In one sizable glass enclosure is a server bank glittering like a chunk of lava, just like the WOPR computer from the movie “WarGames.”

2. The block is flipped onto a cart for bottom-end installation. Lifts are handy for 140-pound cranks.

Line employees rotate every hour, and everyone we saw wore a pedometer. Pass a certain threshold, and it’s good for a health-insurance discount the following year. The recreation area is less than 15 minutes away, and there’s even an employee-volunteer straw-bale garden that delivered more than 500 pounds of produce to local charities last year.

Engine production begins north of the central courtyard with machining activities on the block line. Our visit coincided with a large group of enthusiasts from the Turbo Diesel register, so we didn’t see it this time, but have in the past. Apart from the windows, it’s similar to other block machining facilities.

3. Camshafts are installed carefully by hand. With the engine inverted, you don’t have to secure the lifters.

4. This bank of robots fits rings and joins connecting rods to pistons.

5. A short block complete with seals, front plate and noise reduction.

6. The cylinder head with integrated minimal intake manifold is lifted into place. That makes it easier on the employees, and the head bolts never fall out.

7. We won’t tell you what kind of hat the front cover tech was wearing, only that we waited for him to take it off.

8. The red cast on this engine is not from a test. It’s the barcode reader for the injectors.

9. After the remaining valve train is installed, the wiring harness is next.

10. Along with the variable geometry turbocharger, output and emissions, the size of wiring harness represents the biggest change from the first BT5.9 engines. Other components such as the turbo and filter housing (not pictured) are plugged in as needed.

10A. The exhaust manifold, EGR and turbocharger are assembled separately, then joined to the engine.

11. This complete engine is en route from testing to painting. Each engine is started and briefly run (with fuel and oil, without coolant). There are myriad checkpoints along the line, and if an engine doesn’t pass one of them, it is pulled, sent to repair, set to spec, and then it rejoins the line.

12. Although the block arrives at assembly finished, the complete engine is masked off for the paint booth, where a sealer is applied.

13. This is not blue paint; it’s merely a coating formulated so it looks blue while it’s wet.

14. The drying oven. Note the blue has disappeared, and the engine appears clear-coated now.

15. We don’t know if management told everyone to be happy, but like everyone else, this post-paint team looks pleased.

16. From CMEP, the engines are trucked to Chicago, then loaded on trains bound for the Saltillo Ram assembly plant in Mexico.


G.R Whale writes a great piece called "Whale Watching". It is the best thing about Truck Trend. Some great political commentary.

This is off topic but interesting - Navistar is sueing the EPA. They won one suite and now has filled a second suite. It all has to do with DEF systems versus non-DEF systems.
Way to go Navistar.

Ford didn't win the 6% grade shootout. What the heck are you talking about??? The ford gas engine won, but the diesel certainly wasn't the fastest up the grade. Try again Daivd. And if your going to say ford won the 6% grade, show everyone in writing or video.

Bob, It was the 7% grade.

"The fastest one-ton truck up the hill was the Ford F-350..."

@ Michigan Bob - why is it you never mention the GM HD gassers?
You don't seem to talk much about 1/2 tons either - other than the 5.3 MPG advantage in V8's.
What kind of real world MPG are you getting in your truck?
How does it tow?
How does it haul?
The best I've gotten is 15 city/20.4 highway. The 20.4 came with the back full of camping gear.

Why Mexico? Because it is better than Japan.

At least Mexico is still part of America!

Why don't I mention gasers Lou? I can freely admit that fords 6.2 liter has more hp and torque than gm's 6.0 liter and ford wins this matchup. But again, the Duramax beat the powerstorke in this grade, quarter mile unloaded, quarter mile loaded, 16% grade you name it and the Durmax beats the powerstroke. I know this really, really gets under the skin of you ford fans because you think the sun rises and falls on anything ford.

GM is outgunned in gas engines and even though the Duramax doesn't make the most horsepower or torque it still is the Champ when it comes to diesels.
Satisfied lou?

@Bob, I think Ford deliberately dogged the new Powerstroke down for fuel economy and reliability (after what happened with the 6.0). I think when GM brings its all-new Duramax out with CGI block and reverse flow heads, the power war is going to go to a whole new level, and GM is going to force Ford to show the true potential of the Scorpion. Also, there is no doubt that Ford Super Duty needs a new chassis to handle that potential. I think we all win in the end.

One good Diesel built by another MFG. ten years ago, big yippy.

Build your own, then talk!

Oh wait, you cant. This is why they invented the NUMMI plant.

@Alex correct VM Motori did that design.
@ Lou, only some of the problems Navistar has at the moment, I believe what I term the "Starlight Express" is not selling very well
CAT is having problems with the NC2. NC2 was the joint venture between Navistar and CAT. They built 500 trucks just before Euro 5 was implemented Australia earlier this year at CAT's Tullarmarine plant in Melbourne. Presumably the CAT version is a better built truck, but like the International/Navistar it is based it is not selling at all. CAT is seriously thinking of producing the the Vocational models that it introduced not long ago in the US.

Does Ford still own Cummins?
Isn't the Cummins still a converted tractor engine?

@Michigan Bob - satisfied - no.
I already know that the D-Max powered GM trucks won the last few shootouts/tests. I already know the GM gassers did poorly. I already know that Ford's engines will do very well in a 1/2 ton shootout since Ford won last time with the 5.4 running against bigger engines. Please note - I am not predicting any wins by anyone.
I do not bring up Ford's wins every time I post.
Why do you need to bring up GM's only win(well, 2 wins) every time you post?
You also did not comment on your real world experiences with your own truck.
Why is that?
Does your truck get better MPG than my truck?
How does your truck compare to mine or any other new truck?
I'm just as curious about personal experiences as I am with magazine tests.

@Jim Ed ,Ford has never owned Cummins. Cummins is a worldwide producer of diesels. They have major design and manufacturing in England and India as well as the US.
They produce a whole range of engines.

@Robert Ryan,

Ford did own a percentage of Cummins back in the early 90's. Cummins bought it back.

@Robert Ryan - I agree with Frank. Ford used to own 10% stock in Cummins, but that was a real long time ago.

@Frank - didn't Bob say he had a lowered car er I mean Avalanche????



@Lou asks, "Is it a coincidence that PUTC is testing HD's and then posts a story on how the Cummins engine is made? The upset winner of the 2011 HD shootout?"

My sources say no.

The order will be:
1) Duramax
2) Cummins
3) Powerstroke

The druamax will win another shootout and you can take that to the bank.

Let it be written. It shall be done!

Lou ,

Everyone here is a bunch of sore losers!

GM designed the Duramax alongside Isuzu.
GM designed the Allison transmission alongside Allison.
GM designed the truck by themselves.
GM designed the Vortec engine by themselves also.
All 4 are made in the USA.

Ford designed the Powerjoke and Torqshift transmission by themselves. The Powerjoke uses GM patented technology like the Iron Graphite block and Valley mounted turbocharger. Ford designed the truck by themselves. They also designed the 6.2 by themselves. The powerjoke is made in Mexico. Some Super Dutys are made in Mexico. The 6.2 and transmission is made in the USA. The Ford needs more calibration. A 6.2 gas and 6.7 diesel should not share a transmission.

The Dodge has a cummins designed engine. The cummins engine was "treated" by chrysler to boost the power. With that goes all the historical reliability of the Cummins. Its normally what happens when you dump in more fuel and dont boost the engines cooling system. The transmission was designed by Chrysler, as was the 5.7 Hemi and the Truck. The 5.7 and the truck itself are all made in Mexico. Only the transmission and Cummins are made in the USA.

Looks like a big win to Chevy for me.

Oh, I would love for ford to finish in 3rd in this contest. That would really upset the ford fanatics on this board. They would cry and cry and say the test wasn't fair. Then they would brag about selling the most heavy duty's because they can't win the shootout. Oh how sweet that would be.

@ Billy Bob or what ever your name is, a GMC commercial is not proof.
Spoof yes, proof no.

The order you posted reflects engines not trucks.

How did the GMC diesel do in the 2010 shootout?
Barely won.
How did the GMC gasser do in the HD shootout?
Slaughtered in 3rd place.
In the last 1/2 ton shootout the F150 won with the 5.4. Everyone can agree that it has way less power than the competitor's 5.7's and 6.2 engines.
The F150 still won.
Why does Ram trucks have the biggest sales gains?
Didn't they come in third with the diesels,
and 2nd in gasser HD's?
There is more to a "winning truck" than the engine.
Ford's dyno figures on the 6.7 PS are also proof of that.
The most powerful dyno truck that lost.
I rather look at the data and pick the truck that matches my needs the best. Where it ranks in the test track pecking order doesn't mean a thing if it doesn't meet my needs.
I'd rather look at wheel hop, and/or braking, and/or stability, and/or comfort, and/or driver fatigue and/or smart features. Reliability and durability are the most important factors. How does a magazine test that?
I've grown up. Outright power, and first place finishes no longer matter to me or most adults.
I don't see very many HD GMC/Chevy trucks used in heavy industry where I live. I see Rams and Ford HD's. Most of the GM's I see in heavy industry are base model gasser fleet trucks. My brother gets a new GM every 1 1/2 to 2 years. They don't survive any longer than that (unless you want to spend a fortune in repairs).
They (GMC) upgrade the body and interior to match the diesel drivetrain and they might have a REAL winner on their hands.
Most truck guys will give the nodd to the universal truck guy comment -
A Cummins motor, mated to an Allison transmission in a Ford body/chassis would make the best truck.
Sums it up rather nicely, doesn't it!

"A Cummins motor, mated to an Allison transmission in a Ford body/chassis would make the best truck."

Ford would annihilate the HD Market!

@P. Daddy -
Why would GMC let Ford use patented technology?
Yes - lets develope superior technology like "Iron Graphite block and Valley mounted turbocharger" and not use it ourselves.
Yes - let the competition use that technology.
Yes - lets f-up everything and need another bailout.

Ford would have to get legal permission to use patented technology developed by GMC.

Patents are good for 17 years and one can get a 3 year extension.
Once the patent expires anyone can use the technology.
Did GMC sit on superior engineering for 17-20 years?

Lou take off those ford bias glasses and wake up! Your post above is so full of lies and distortions it is obvious that you have a hard on against GM. I am glad you think ford is the best truck for you and you can buy them till the day you die. but your lies and distortions about GM really shows your outright hatred for anything GM.

Sorry Lou, your powerjoke diesel was handily beaten by GM'S Duramax. Those are the facts and nothing but the facts. The duramax will beat ford again Lou and you can take that to the bank. Have a nice day now....

bob, who sells more HD trucks?

@Bitchagain Bob - truth be told,
I'd buy a Ram HD if I were in the market for a diesel pickup.
I'd buy a PowerWagon if I wanted a HD gasser.
I'd buy a Ford HD gasser if I was going to tow a lot.
I'd buy a Raptor if hardcore offroading was my end goal (and price was no object).

Where did I lie?

Please post your evidence.

If you prove me wrong, I'll apologize and not post until the HD shootout hits the e-pages of this site.

GMC sources do no count as evidence.

You talk a mean game but the only thing you've ever admitted to driving is an Impala. If that is the case, I don't blame you for having a chip on your shoulder.

@Buy American or say Bye to America!,

So I like how you flip flop...

Anything made in Mexico and sold in the U.S. is considered an import!

Mexico's flag is not even close to ours nor is their language, for now and different government...

@Lou and @Frank thanks for the correction.


How have I flip flopped? I have always stated; The United States of America's best interests are my number one priority! Made in Canada/Mexico (North America) comes next. Made (anywhere) in South America is my final loyalty.

Sorry Asia, Europe, etc. I take care of my own first. Especially when my own (U.S.A.) is struggling and needs help compared with others (Asia) that are thriving.

@Robert Ryan - thanks.

How about a story on making Ford's 6.7?
Just make sure your passport is in order ;)

Maybe Mike can do a story on the Chrysler Trenton Engine Plant, next. This is the place that is making the Pennstar V6 for the Ram in 2012. Just don't forget to stop at the party supply store and UAW lot on the way.

Chrysler employees caught drinking, smoking during lunch break... again

How about a story on Toyota's 6.7? Oh wait.. there isn't one!


Real truck guys, with real work to do, know that there are only four choices for pickups. Toyota is not one of them. It boils down to; Chevrolet, Ford, G.M.C., or Ram.

@ Alex - Toyota did look at the HD pickup market. They had a 1 ton dually at the 2007 Sema show. It had an 8 L I6 with 300 hp and 600 lb ft of torque. Hino has engines in the range of smaller I 4's with 210 hp and 400 lb ft torque up to 7.68 L and 260 hp and 660 lb ft of torque.
The I 4 with 400 lb ft of torque would be a good 1/2 ton engine.
It made sense for Toyota to stay out of the 3/4 and 1 ton markets as they already have a hard time selling Tundra's in the numbers they would like. I do know guys who have say they would buy a 3/4 ton Toyota truck if Toyota made one.

The Treasury Department reported today that U.S. taxpayers lost $1.3 billion from the Chrysler bailout after Fiat bought the remaining U.S. shares of Chrysler. I am sure that Chrysler will be reporting, "We paid all of our loans back the the taxpayers." The problem is that we only received back $11.2 billion of the original $12.5 billion that we loaned them. Even though we were charging interest, that is how much less Chrysler stocks are worth today than when the taxpayers were forced to buy them. Don't you feel patriotic?

@ Brian - that isn't Fiat's fault.
The governments of Canada and USA made the mistake of getting involved in the first place.
The USA government and to a lesser degree Canada bailed out Chrysler by purchasing shares or stock in Chrysler. That purchase was based on an inflated value for that stock.
Another component of that bailout were loans. In Fiat's case -high interest loans.
Fiat secured private loans to pay off the government high interest loans and bought shares giving them 51% interest in Chrysler. There was a story saying that they chose to buy 51 % early because stock was low and therefore cost them less. It also cost them less to borrow private money and pay off the government.

@P Daddy,

The Dodge RAM has the most American content of any American truck !!!!! Only the RAM H.D is made in Mexico.

Ram 1500 regular cabs are made in Mexico.

As well it would not be economically viable to sell a unique diesel engined model in relatively small market.. That market is 180,000 to 200,000 for Ford, GM and Chrysler?

@Robert Ryan - good point. Toyots would never make a profit on a diesel at the volumes they currently sell.

#1 selling HD diesel pickup truck in Canada? The RAM. Fact.

why do you guys think the dodge is goin to loose?everybody thought fords new v8 was the best engine out there and chevys little 765torque 397 hp showed it up?and i think its funny how ford and dodge have the same amount of torque but dodge still has better towing and can handle the weight better,every test i seen with a ford in it it cant pull over 12K without shakin the truck all over the road,its like chevy said it just aint the engine or the trany its how the power moves though out the truck,dodge has the best diesel exhaus towing longest lasting,it will climb the hill at 2500r.p.m's while the v8's clims at 3,800.i heard from people that own the 350hp 800 torque 2011 dodge trucks,the 350 hp feels like 400 it gets up and goes,and we did a dyno test on a 2011 ford powerjoke rated 400hp 800 torque it only got 304hp and 520 torque,the guy took it back to the dealer they took the truck sent it bak the the factory and gave him another,wouldnt tell him what was wrong with it and they still havent.if dodge or chevy dont come out on top ford cheated again like they always have,the Il-6 is the best diesel engine,thats way every 4 years when dodge has to renew there contract with cummins fords trys to rush in and take cummins, but cummins says no to them every time ford whats cummins,and i wouldnt trust the new 6.7 powerstroke it could be the new 6.0(only last 100,000 miles) or it could be the new 7.3(fords best engine)nobody knows its reliabilty,dodge has had the same proven engine for over 25 years,chevy has had theres for over 10 years ford changes theres every 4 years due to recall on there trucks,engines,tranys,rear-ends,drive shafts,ford has recalls everythime you check pickuptrucks news,buy a dodge put chevy trany in it you got the best truck out there,next year dodge gets new engines,and tranys and this year they did there rear-ends that is supposed to be better than ford and chevys,next year when dodge gets there new heavy duty tranys there goin to pass ford and chevy,ford just wants your money chevy wants to get out of its dept dodge keeps tryin to prove its reliabilty,and i heard ford asked cummins to help them make the new powerstroke so cummins drew up the ideals,how come theres dodge trucks with cummins engines with 1.2 million miles,no rebuilds on the trany or the engines, fords longest lasting engine is only 500,000 thats the 7.3 and thats if you take cear of it,chevys are around the 700,000 but by then people that own them are tired of there drive shafts goin out cuz chevy dont know how to make a drive shaft for a diesel so the chevy guys switches to ford then the fords 6.0 blows up and they switch to dodge then there trucks last 1 million miles ford wants your money,dodge and chevy are tryin to build a truck you guys just dont listen to the facts you just go for the first truck you see dodge and chevy all the way ford is just dumb,my cuzin has a 2006 durmax great truck last for ever gots 400,00 miles its got 600hp and 956 torque,we hooked it up to stock 2005 dodge diesel the dodge pulled it backwards twice the thired time the chevys started to pull then guess what the drive shaft went out theird time that year,we got a 92 power ram 250 700,00miles stock trany stock everything,still working great,had a ford 6.0 lasted 100,400 miles the engine blew up got it rebuilt did it again 100,037 miles later,if you want a truck go with chevy or dodge dodge has babd tranys(gets new ones next year)chevys got bad drive shafts(dont know when there goin to fix them)

and our 92 dodge cummins can tow our back-hoe and goose neck up hills 2500r.p.m's our ford which was newer then it couldnt climb them under 4000r.p.m'sdodge and chevy are goin to come out on top

and if you want proof ford dont trust its engines or tranys thats while there power train warrents is so low go look at the f-650,750,its got cummins engine and chevy trany,think about that while your found on road dead in your ford watchin the dodge cummins with 1.2 million miles go by and the chevys with 500,000miles dragin there drive shafts and dodge tranys fallin out dodge needs new trays get them next year chevy need newer drive-shafts may have already fixed them,ford needs to stop a redo there trucks,tranys(ENGINES)

@Ram - I get the distinct impression that you need way more fibre in your diet.

Go to the FORD website and look at the Medium duty trucks F-600 and up. Tell me what engine they use....the same one in the dodge light duty 2500 and 3500! Why wont they use the Powerstroke? It's not durable enough. Just because the Ford and GM get to the hill quicker doesnt make it a better engine or truck. All of these truck can be semis truck to the top of the hill but that surely doesnt mean they are better towing vehicles than a Semi tractor.

When it comes to diesel you have to admit that the Cummins inline six is a superior design, Just look at the facts; an inline six has SEVEN main bearings versus five for a v-8, and they are almost TWICE as big! The Cummins inline six is naturally balanced because of the 153624 fire order. The stroke is longer on an Cummins inline six than a comparable v-8, and that is where TORQUE comes from. A v-8 Duramax or Powerstroke can get rpm's easier, but a Cummins inline six will have the low end grunt that a diesel is made for and that's why there is NO comparison.

I'm interested in such offer,The sound quality in these podcasts is really poor. I feel bad about complaining about something that is free, but I think it is important.

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