What engine with DEF is having the least amount of problems?

The ISX15 in my company Pete is a 2013 and its had very little trouble. Had a couple sensors in the exh system replaced but nothing major. Truck has 318,000 miles on it and close to 10,000 hours. Haul a lot pneumatic loads so it spends a ton of time at 1400rpm no going anywhere while loading or unloading. We haul heavy 105,000 gross here in Washington and Oregon and I seem to have less issues then our other truck but I run her really hard when I do to keep the exh hot and I think that is the key to having little to no issues with the exh system. Oh and never interrupt the regen unless you absolutely have to. If my truck is regening when I go to park for the night or what ever I will start a parked regen so it can finish its burn.

 

Ask this question, you'll get just about every answer there is. Detroit and Cummins are the two I keep being told.

 

If a Cummins is being rebuilt before 200k, I have a feeling it's more a matter of abisive treatment than it is the engine. The ISX has its quirks, but not to where it gets rebuilt before 200k. Now I have seen some where the rear structure needed to be resealed or the injectors needed to be replaced within that time, but not an entire rebuild.
There are two generations of PACCAR MX… either one uses the same Holset aftertreatment system used by Cummins… the only real noteworthy difference is the type of plug used on the dosing injector. Gen 1s had recurring problems with belt tensioners and water pump seals, and the occasional back pressure valve. A lot of people #####ed about the location of the dosing injector, as well, although I can service one almost as quickly as I can on a CM2250 Cummins, and actually quicker than I can on the older model ISX with the dosing injector on the back side of the exhaust pipe.
Gen 2s sure seemed to need a lot of software updates initially, as well as some other teething troubles, which for the most part seem to have been rectified since.

 

The 06 trucks are bring top dollar these days.....

 

Yes. I worked for a carrier which had gone from the ISX as their main squeeze to the PACCAR MX. I was also a driver and equipment operator for 10 years before I started wrenching, but I have no experience with either engine as a driver.

 

ISX is not that problematic, not anymore at least as i hear. I think more people dislike the MX motors because they are so difficult to work on. I presonally drive an isx15 manufactured in mid 2015 and i havent had any serious issues so far. Only minor things that i was able to fix on my own.