6.7 Cummins vs 6.6 Duramax
As someone who knows next to nothing about Diesel engines, I am trying to figure out the strengths and weaknesses of these to. Any opinions would be appreciated.
Forum Discussion
I can reply to this with a little different perspective. For a living I am a self employed mechanical inspector. If it has wheels and drives I’ve probably done a mechanical inspection on it. I’m hired by insurance companies, extended warranty companies, manufacturers, lawyers, and others. From my experience both are good engines. However of the 3 main light duty truck Diesel engines (ford 6.7, Cummins 6.7, duramax 6.6). The duramax is the least dependable. All generations of the duramax 6.6 suffer head bolt stretching that leads to head gasket failure. This is especially true in cold climates. Head studs seem to take care of the problem but that’s after 20 hrs of work and $2500 in parts. The cummins seem to have the least trouble of all 3. And since the earlier cp4 pump disaster in 6.4 fords. It has tuned out to be a pretty reliable pump. The Alison tranny is better than the 68RFE however if both engines are left with stock power levels the 68 has been a strong transmission too.
