If you’ve been following the greasy gearhead corners of the web lately,  big truck division, you’ve probably noticed a fair amount of doubt regarding Ford’s decision to boot Cummins and go it alone on powertrain options for their new F650 and F750 big trucks. Now the Cummins in question, the six cylinder B series, has become something of a legend for it’s durability- I drove one on occasion that was driven by everyone and put away wet, but still managed 15,000 hours without a rebuild before it was traded off. Heck, the B series probably put off Hostess’ bankruptcy for a few years, with still running two and three decade old examples with over half a million miles on the bankruptcy filing’s inventory lists. So it’s no wonder that almost every big truck maker offers the Cummins B series and sometimes only the B series in their medium trucks. So it comes as a surprise (some would call it treason) that Ford would evict Cummins from it’s home under the hood of their medium trucks.

Examined a bit more closely, Ford ain’t dumb-  The Cummins B series is a great linerless medium duty diesel, but it’s no big block where you press out the liners and press in new ones come rebuild time and truck on for another million miles. But the B series is no “throwaway” engine either, just send it to the machine shop for an overbore and fit the appropriate new pistons and rings. Same with Ford’s own diesel, and GM’s Duramax. But fact is, most users will never put on enough miles to rebuild these engines, which routinely come with hundred thousand mile warranties even in overblown pickup power ratings. And Ford is certainly no novice at building diesels, their own foundries and assembly plants having borne reliable diesels for over half a century now.

But is Ford’s own diesel a match for Cummins B series? I’ve found no publicly available data for medium trucks, and it would be nice if some of the big fleets like the GSA or the Postal Service’s that probably have some of each brand of medium truck powertrain in their fleets would turn loose their data. But our old friend and source of a treasure trove of big data, Consumer Reports, has been tabulating the totals for some of the big trucks little brothers, the half and three quarter ton pickups. This data is relevant because Ford’s new medium trucks are basicly the Super Duty pickups with bigger axles, brakes, tires, etc. stuck underneath and the engines derated a bit. Same thing over at Dodge, where the Cummins B series has taken up residence in their three quarter and one ton pickups.

So what does Consumer Reports report? First let’s look at the standard of the industry, the Cummins B series in those Dodges- While the Cummins engine itself has been “above average” or “much above average”, it’s fuel system has barely improved to “below average”. Looks like the Cummins durability is still there, but Cummins isn’t doing so well at producing a reliable injection system to meet current emmissions standards.

Over at Ford, their diesel engine has shown “much better than average” durability per CR’s survey, with the fuel system improving to “better than average”. That strongly suggests that Ford’s own diesel engine will work just as well and long as Cummins B series. As for service availability, one of the benefits of Cummins power is the availability of service in far more places than Daimler’s, Paccar’s, Volvo’s, and Navistar’s proprietary engines… Which explains why most of the above are offering the B series as an option or even sole offering in their trucks. However, Ford has more dealers in more places than Cummins, and almost all of them service Ford diesel engines. So if you’re in the market for a medium truck, don’t let Ford’s diesel put you off.

And the cons: The comments are coming in on the proposed 2027 fuel mileage standards for big trucks, and the aforementioned proprietary engine truck makers have voiced their disapproval that Cummins will be allowed to certify their engines seperate from the truck chassis they’re mounted in. I take this to mean they’d like to squeeze Cummins out of this market via protective regulations, thusly bring them closer to their dreams of a profitable near monopoly. Meanwhile, some of these same truck makers have made Cummins the standard and sometimes sole engine offering for their medium trucks, avoiding the hassle of certfying their own engines to U.S. standards. In the booming market for natural gas engines, Cummins is the only source for heavy duty trucks and is offered by Daimler, Paccar, and Volvo.

So the big truck makers romance Cummins when they need medium duty and alternate fuel engines, then spurn Cummins in the higher volume heavy duty diesel markets. Some guys treat girls like that, then wonder why they’re lonely…