TIL my shop's 12-valve Cummins rebuild hit 900,000 miles on the original bottom end

We just pulled the head on a '94 Dodge for a customer, and the cross-hatching was still visible in the cylinders. It made me think, is this just a freak engine or are we too quick to tear into things that still have life? I've seen guys rebuild at 500k just because 'it's time'. What's the highest mileage you've seen on a stock bottom end before a teardown?

3 comments

3 Comments

paul2866d ago

Seriously, that's a tough one. My old farm truck went 750k before we even thought about the bottom end, and it was still running fine. Maybe we just fix things that aren't actually broken yet?

gavin6926d ago

Wow, that's incredible! I read a story about a fleet truck with a 5.9 that went over a million on the original pistons and rings. Makes you wonder if we're just following a schedule instead of listening to the engine. Some of these old diesels are just built different.

mason.brian6d ago

But come on, how many of those high-mileage stories are just guys who never checked the blow-by? I've seen a few that were basically running on hopes and a quart of oil every 500 miles. Sure, the cross-hatching might be there, but what about the ring gaps you can't see? Sometimes an engine living that long just means the owner was really good at ignoring noises and topping off fluids.