I made it just shy of 1'000'000 Miles (1.6 mil kms) on my Peterbilt 379 with a CAT C-15 before the head gasket went. Opened up the block to find a dropped liner.... Time for a full on engine rebuild!
A little explanation on the different mechanics and shops I mention in the video. So the first day I notice the coolant leak, I head back to the yard where I work, where there is a small shop and one mechanic. This is the mechanic that helped me out the first day, spotted the leak out of the head gasket, and put in the stop leak. The next day when it was leaking again, I took it to another shop with other mechanics that will actually do the engine tear down. I had to take it to another shop because the one at the yard is not really equipped to do internal engine work, and it's there to service the company equipment, not the owner operator's equipment. My boss was nice enough to rent me the Kenworth in the meantime though, so at least I'm still kind of making money to pay for the new engine!