Posts: 13
Threads: 8
Joined: Nov 2025
I’m looking at a 2012 with ISX 650 Cummins. I’m hesitant because of the 650. Your thoughts?? Thank you
Mike Figley
2014 Coach 1490
Toad- 2022 Denali Hd
Posts: 5,844
Threads: 500
Joined: Jul 2012
i can only speak to a 2013 isx15 rated at 500hp on a cascadia super c weighing all in at 38k lbs. it has 45k miles on it, with a eaton 13 speed ultrashift. pulls like a freight train. doesnt slow down going up hills. got 8mpg on a 9k mile trip this summer. the 650hp i am sure has different injectors,, maybe cam and not sure what else.
i have several buddies who manage fleet truck repair centers and they love the isx. i had zero issues on my last trip.
compared to the series 60 in my 53k lb newell, the isx pulls stronger, but the newell weighs alot more.
my two cents worth
tom
Former Owner 2002 45'8" Newell Coach 608 Series 60 DDEC4/Allison World 6 Speed HD4000MH
Posts: 5,908
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Has the head been replaced
This is MY opinion. If the head has been replaced I would be comfortable. If has not, I would subtract 50k from the price, buy the coach, and immediately have the head work done.
Richard and Rhonda Entrekin
95 Newell, 390 Ex caretaker
99 Newell, 512 Ex caretaker
07 Prevost Marathon, 1025
Maverick Hybrid Toad
Inverness, FL (when we're home

)
Posts: 13
Threads: 8
Joined: Nov 2025
Thank you for the responses!!
Mike Figley
2014 Coach 1490
Toad- 2022 Denali Hd
Posts: 117
Threads: 15
Joined: Dec 2017
You can take the coach to a Cummins approved shop. They can scan the ecm for anything and everything since the engine was installed. Cummins had issues with the 650. I never worked on one but did see more than one that self destructed.
Cummins never really dealt with this as far as I know, but they did warranty some. Lots of my peers have ideas as to the reason, but as Richard said once the head was done the problems appear to be gone.
Mark and Marian
1986 #125 (left us for a new home in Oregon)
1999 Wanderlodge LX40
1979 Mc 8 6V92
Pace 26' stacker
Regina Beach SK Maricopa AZ