Paccar MX or Cummins ISX

The Gen 2 PACCARS seem to have improved a lot. I haven't seen the belt tensioner issues, water pump seal issues, or the perpetually self tightening secondary fuel filter issues I've seen with the 1st gen engines. They did have some teething troubles related to programming initially, which seem to be worked out, but they do seem to need software updates pretty often (although the CECU and dash cluster on PACCAR products seem to, as well). I was impressed with how it pulled for a 13 liter engine being cruised as low as it is. Of course, there's parts and service availability. Also, if you're getting the software to go with it (which I wouldn't buy an aftertreatment equipped truck and not do, personally), INSITE is a bit more user-friendly than Davie 4.
With the Cummins, I've seen quite a bit of sensor issues, especially pertaining to the oil presssure sensor and intake manifold sensor. EGR issues do exist, although I would question the frequency which some claim. I seem to recall their having been a couple campaigns pertaining to injectors, as well.
Both use the Holset aftertreatment system, so they'll both have the same weak points. DPF differential pressure sensors, NoX sensors, DEF heater hoses,the 90 degree inlets and outlets cracking, and the honeycomb on the DOC coming apart are the most common issues I've run across with those. They both also use the Holset VGT (variable geometry turbo) which I'm not 100% how I feel about that.

 

The current 2013 EPA ISX now seems improved a lot as well

I had same question before when I consider the brand new T680

Now I have made my mine to stay away from the PACCER and with Cummis because the better repair network and more aftermarket shop know how to work with it once Warrenety expired

Also there is an option to take off the after treatment system for Cummis Once the warranty expired. If I choose to

It's always good to leave the back door open no matter you are going to use it or not.
This option isn't avalible for PACCER MX13 ....

Just my 2 cents ....

 

Depends on where you're running. If you mostly run flattish terrain, I'd go with the MX13 for a little better fuel economy. For running primarily mountainous terrain, the ISX would be a better choice.

They will tell you that the MX can get as much power as the ISX, and it's true. But the one thing they don't mention is that to get a certain power output, you need to burn a certain amount of fuel. The problem is that increased power in a smaller engine requires an increase in cylinder pressure in order to fit the required fuel/air mixture. To me, that just screams "more wear and stress." The larger displacement will handle the requirements more readily and with lower engine speed.

Look at it this way. A top fuel dragster makes tremendous horsepower, but look at what they have to do for that power. Running insane rpms and rebuilding the motor very frequently. Putting large power through a small motor will eventually cost you. In my opinion.

 

Yes it is, you just need to know where to take it.

 

Hi, new here but also have somewhat of a similar question. We are looking at a 2015 ISX cummins 15L and wondering if this is a good choice? Also has about 200k km on it. Thanks for any input and sorry if I hijacked the thread.

 

I'm looking at a 2012 to 2013 pete 386/587.... Most I have been finding have the Paccar MX and some with the Cummins Isx but rare.

I have not driven either or so it's tough to make a choice. I know the Cummins Isx has 485hp and I have seen some Paccar Mx with 485hp.

As for what someone said it goes through a lot more wear and tear with a small displacement motor producing same power as the 15L.

I plan on driving the truck city/some highway till I can go strict highway.

I have seen some kenworth straights trucks in the shop all the time with paccar and me driving the straight truck with a cummins flys!!

I am somewhat leaning towards the cummins

 

Go with a 2013 if you really want a def truck.

 

If you get the mx make sure it is the 2nd generation version. First generation had a lot of problems.
With cummins isx in 2012 and 2013 area you have to be sure the fuel pump was changed from ceramic plunger to the updated version. This was a big issue. The ceramic ones would break apart and send bits into the injectors and the motor is finished. There was something about cummins decided not to warranty it, but it would cost them less to buy a few engines rather than replace all those fuel pumps. Something like that anyway. Outside of that the isx is a good motor. Mx reports better mpg but is sluggish. Personally I don't want the mx motor. You would be limited to paccar shops to have it worked on should the need arise.

 

The 2nd gen paccar came in what year pete/kw? As for the cummins 450 or 485hp? I would think it's the same motor just tuned a bit different?

 

Hey friend, is there a difference between the def systems from 2012 to 2013?