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120920_MX_hero Paccar’s MX13 diesel engine has power ratings from 380 to 500 horsepower. Torque ratings range from 1,450 to 1,850 lb.-ft. The engine features a compacted graphite iron block, a high pressure common rail fuel system and a 1 million mile B10 design life.


Featured reviews:

25-truck fleet in Southwest

3.9 Rating
Reviewer Comments In terms of power, performance and fuel economy, they are great. My drivers really like them. My only complaint so far is that not a lot of people know how to work on them yet.

We’ve been running the MX13 for 8 months now. I bought three for starters and since have added six more. In terms of power, performance and fuel economy they are great.

My drivers really like them: We have a fleet mixture of Cummins and Detroit power. And the drivers tell me the PACCAR is the quietest engine of the bunch. They say you can’t hear the turbo spool up and engine brake noise is nonexistent. You can feel it kick in – but you can’t hear it.

Fuel economy is a definite plus. Some of the engines only have about 15,000 miles on them; others have around 75,000 miles. But all of them are routinely in the mid-6s on MPG. And one guy – my best driver – is consistently getting 7.5 MPG. But he thinks anything over 62 mph is speeding.

My only complaint so far is that not a lot of people know how to work on them yet. And no one can read the engine software. My Kenworth dealer can. But I’ve had five “undefined” codes on the engine so far. What is an “undefined” code? I have no way to find out and I can’t always be running the truck by my Kenworth dealer so they can put their PACCAR diagnostic machine on it.

I’d like more information when I get a fault code. I’d like to be able to do the diagnostics in my own shop. But in a lot of cases, the Kenworth dealers still don’t have the diagnostic equipment, either. As far as packaging goes, it’s a very-well designed engine. Both in terms of filter and component placement and access to major systems.

It’s a very technician-friendly engine. It’s also a driver-friendly engine in terms of a pre-trip inspection. Really, the only thing I’m nervous at the moment with this engine is breakdowns out in the middle of nowhere.

They’re so new you pretty much have to go to a Kenworth dealer to get them repaired. That goes back to the software that I mentioned. You can’t call an outside repair shop. Most of them aren’t trained on the engine and don’t even know what they’re looking at. I’m hoping PACCAR brings them into the fold and gets them some training soon so I can get a repair if one of my guys does get stuck out in Timbuktu or somewhere.

See the breakdown
  • Suitability for your application/business 4
  • Overall reliability/durability 4
  • Overall engine design 4
  • Serviceability 4
  • OEM support 4
  • Dealer support 5
  • Fuel economy 4
  • Horsepower rating 3
  • Torque rating 3
  • Acquisition cost 4
  • Resale value 4

96-truck fleet in Northwest

4.2 Rating
Reviewer Comments The fuel economy on the engines has been good. In fact, they’re getting the highest MPG numbers for any engine in our fleet right now.

So far we’ve been pleasantly surprised by the engine. We don’t have a lot of miles on them yet. The highest-mileage engine is at 85,000 miles right now. But they’re doing a good job. The fuel economy on the engines has been good. In fact, they’re getting the highest MPG numbers for any engine in our fleet right now. The drivers are generally happy with the engine.

The only complaint I get from them is about the engine brake. And really, Paccar has a good brake on this engine. It’s just that the drivers are used to the Cummins brake on the high-displacement engines. And that’s a very aggressive engine brake. So they don’t think the stopping power is as good. But it is.

Maintenance has been very good. We haven’t had to do any serious repair on them yet – just general service and tune-ups. But the packaging is good and access to the engine is good. Our service support has been very good.

The only thing I don’t like about the engine – well, it’s not the engine: It’s the way Paccar handles the fault codes you get off the engine software. The whole process is too cumbersome. You have to download the fault codes and send them in to Paccar. Then they look at them and send you a fix. The process takes too long and needs to be streamlined. It’s just too complicated.

See the breakdown
  • Suitability for your application/business 5
  • Overall reliability/durability 4
  • Overall engine design 4
  • Serviceability 4
  • OEM support 3
  • Dealer support 5
  • Fuel economy 5
  • Horsepower rating 4
  • Torque rating 4
  • Acquisition cost 4
  • Resale value 4

Other comments:

20-truck tank carrier in Southwest

Reviewer comments

It’s an incredible engine. I tell people all the time, in my opinion, the best diesel engine ever was the Detroit Series 60, and the MX13 is going to go down as being just as good. It’s a great engine – easy to work on and extremely durable.


*Averaged from 9 qualified fleet reviews

3.6 Average*
  • Suitability for your application/business 4.3
  • Overall reliability/durability 3.6
  • Overall engine design 3.8
  • Serviceability 3.6
  • OEM support 3.2
  • Dealer support 4.1
  • Fuel economy 3.8
  • Horsepower rating 3.4
  • Torque rating 3.4
  • Acquisition cost 3.2
  • Resale value 3