That old diesel hand who told me to quit babying the throttle

I had this guy in his 70s come by the shop last month while I was working on a 6.7 Cummins. He watched me feather the throttle during a high idle relearn and just shook his head. He said "you're gonna glaze those rings running it like a sewing machine, give it some welly." I thought he was just old school and set in his ways. But after the truck kept having trouble with oil consumption on startup, I tried his way on the next one. Stabbed it to 1500 right out of the gate during the relearn cycle and let it hold there for 2 minutes. That motor settled in smooth and hasn't burned a drop of oil since. Anyone else had an old timer correct something they thought they knew about break in procedure?

2 comments

2 Comments

nora1841d ago

Am I the only dummy who thought "feathering it like a sewing machine" was the proper way to be gentle on a motor? I was doing the same thing, babying the throttle during break in on a fresh rebuild, and it smoked like a chimney for weeks. Old timer at the parts store laughed at me, told me to "drive it like you stole it" for the first few hundred miles. I felt like a real idiot when I actually listened and the rings seated up perfect. Now I'm the weirdo telling people to stab the throttle on a cold motor during break in and they look at me like I've lost it.

alice_wilson731d ago

Is it just me or does that old timer advice always end up being right... I had the same thing happen with my old 302. I babied it for like two weeks thinking I was doing the right thing and it just kept puffing blue smoke every time I started it. Finally took it out on the highway and ran it hard for a few miles and it cleared up almost immediately. The rings need that pressure to seat against the cylinder walls, that's just how it works.