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So, I've been looking at 3 different sources: 6.7L diesel technical overview from 2011, the 2015 diesel supplement, and the 2017 owner's manual.
The 2011 technical overview places capacity as 29.4 qts primary and 11.7 qts secondary.
The 2015 supplement states capacity as 30.3 qts primary and 10.8 qts secondary.
The 2017 owner's manual puts capacity at 35.1 qts primary and 15.1 qts secondary.
Now granted, these are 3 different engine generations of the 6.7L. I'm not surprised to see increases as power and torque rises. I'm skeptical of the 2011 numbers - did the secondary coolant capacity actually drop for the 2015 engine?
This is a good question and no one is sure what to believe. The owner's manual also says the oil capacity is 15 quarts but we're now hearing from some who have actually done an oil change and the engine only took 13 quarts. Same as the previous generation.
So what do you believe on the cooling capacities? Do you believe in the increased capacities and then find out that it's the same as 2016? Or have they truly increased and for what reason did they? We talked about this possibly being in anticipation of increased HP and TQ numbers soon coming but that didn't pan out with in the oil capacity case.
Exactly. When I initially saw the capacities of oil and coolant increase, I figured it was to do with increased heat generated by the higher output engine.
However, it apparently is confirmed oil capacity remains the same as before...and like I said, overflow tanks are identical, radiators "look" identical...so where would the extra coolant be?
I'll add this...finally floored the 2017 last night once in 2nd gear...which is where the torque-limiting stops in duallys. This truck feels stronger in mid-range, but no stronger on top end than the previous 440/860 truck. That seems like it would make sense considering no HP gain. Smooth engine, more coolant or not.