7.3 vs 6.7 … which one should I pick?

I’m shopping for a Ford diesel and I’m torn between the 7.3 and 6.7. I used to drive a Chevy LLY, but switched to an F150 a few years ago. Now I want to get back to diesel trucks because once you’ve driven one, it’s hard to stick with gas.

I’ll be honest, it’s mostly going to be a daily driver, though I’d use it for towing every now and then. My budget is around $40k, so I could get a 2013-2015 6.7 with 100-150k miles or a 7.3 with similar mileage (if I can even find one). I like how smooth and modern the 6.7 is inside and out, but I’ve read way too many posts about CP4 failures, turbo issues, and other problems.

On the other hand, the 7.3 is old-school, simple, and reliable, though I hear it has transmission issues. Am I overthinking this, or are the 6.7s really that problematic?

I own both, and the 6.7 is better in almost every way. If you’re worried about reliability, get a 2015 or newer. By then, most of the issues had been fixed, especially if you delete and tune it.

Scout said:
I own both, and the 6.7 is better in almost every way. If you’re worried about reliability, get a 2015 or newer. By then, most of the issues had been fixed, especially if you delete and tune it.

Totally agree. Forums tend to exaggerate issues. The early 6.7s had some growing pains, but those are mostly resolved now.

  • Turbo issues? Only 2011-2012 models, and most have already been upgraded to turbos with steel bearings.
  • Spun bearings? Extremely rare and limited to very early 2011 builds.
  • CP4 failures? Overblown. It’s usually from people dumping DEF in the tank, not draining the water separator, or using bad fuel.

The 6.7 is solid if you maintain it well.

The 6.7 isn’t problematic at all, especially the 2015 and newer models. The second generation brought in a stronger CP4.2 pump, a bigger turbo, and exhaust braking. It’s a powerhouse and super reliable if maintained properly.

  • CP4 failures: Usually caused by DEF or bad diesel. Stick to busy fuel stations and change filters regularly.
  • Turbo issues: Fixed with the 2015 update.
  • Spun bearings: Very rare and mostly manufacturing defects.

If you can, stretch for a 2015 model—it’s worth it.

I’ve got a 7.3 with 345k miles and a 2012 Duramax dually with 145k. Here’s my advice:

If you go with the 6.7, add a bypass kit to protect against CP4 issues and use a good diesel additive like Optilube. Biodiesel is also great for lubrication. If emissions are deleted, you’re golden.

The 7.3 is fun if you like older trucks, but it’s loud, slow, and unrefined. Still, it’s a workhorse if you’re okay with that old-school vibe. Either way, enjoy your choice!

If you’ve got $40k, go for the 6.7 without a doubt. Avoid the 2011-2012 models; the 2013-2014s are better but not perfect. If you go for a 2013-2014, set aside $3k for a better turbo. The 2015+ models are bulletproof and have more power too.

The 7.3 is incredibly reliable, but they’re ancient compared to modern trucks. With $40k, you can find a 6.7 where all the known issues have been addressed. Keep in mind that a lot of problems with these trucks come from poor maintenance or people driving them like sports cars.

I had a 7.3 for nine years. Great engine, but it was rough, slow, and had constant minor issues like oil leaks and alternator failures. Transmissions are also weak if you add power.

For $40k, get a 6.7. It’s way smoother, more powerful, and less hassle to live with daily. The 7.3 is a great workhorse, but it’s showing its age.

For $40k, why not get a Ram 3500 with the 6.7 Cummins? It’ll outperform both.

Heath said:
For $40k, why not get a Ram 3500 with the 6.7 Cummins? It’ll outperform both.

This is a Ford forum, buddy. Keep it relevant.

I have a 2011 F350, and it’s been solid. I deleted it recently, and that takes care of a lot of the common issues. For CP4 failures, keep receipts for your diesel purchases in case bad fuel causes problems—you might be able to hold the station accountable.

Having owned both, I’d take the 6.7 any day. It’s faster, just as reliable, and way more comfortable. The 7.3 is legendary, but it’s old and noisy. Plus, you’ll spend more time fixing non-engine issues on an older truck than you would just buying a newer 6.7.

The 6.7 is a beast of an engine. It’s powerful, modern, and reliable if you do some minor upgrades (like exhaust work). The 7.3 is tough and simple, but it’s dated and needs a lot of mods to keep up with modern trucks. If you’re spending $40k, get the 6.7—preferably a 2015 or newer.