Cat C 7

They self destruct by dropping valves and cylinder scoring etc. The valve trains are weak and overall they weren't designed to last into the high mileage range of larger engines.

 

That is a small displacement engine. It is not much bigger than what you can buy in a pick up truck. At one time Ford offered a 7.3L in there pick up trucks. With that said they are not great on mpg and they are over worked. They could have had the same horse power with a larger engine and less gearing in the axle and likely got better mpg and a less over worked engine. Plus better resale value.

Perfect example is we have a international dt466 (7.6L); 32k gvw single axle and a 6 speed the only gets 7.2 mpg on the highway. Because it is running 2300 rpm at 65 mph a C12 running 1500 rpm at 65 with 80k gvw will get about the same mpg. We could have bought a truck with an M11 Cummins 250 hp and 3.08 gear and got near 10 mpg with the same single axle tilt bed truck. It would be idling going down the road and have no work load.

We run locally with tilt beds for lumber. We will NEVER buy another international or a truck with a motor smaller than 10 liters. A

 

When I worked for Pepsi, my truck was a GMC TopKick with a Cat 3126 which I believe the c-7 was descended from. It was mated to an Allison 4 speed auto and had a 4:88 rear end on 11R22.5 rubber. It was geared for local runs but my route had a 110 mile one way highway run. So consequently it was bumping the governor at 2500 rpm at 64 mph. It had to be rebuilt after 400k when they determined it had almost no compression in any cylinders.

Fwiw, it too was a Penske lease truck.