I used to swear by the old school method for setting valve lash on a 12-valve Cummins

For years, I'd set them cold with a feeler gauge, fire it up, and adjust again hot. It worked, but it was messy and took forever. About six months ago, a guy at a shop in Boise showed me his method: set them all cold to the tight end of the spec, then just run it. I was sure it would be noisy, but on my personal truck, the valves have been quiet and perfect for 5,000 miles now. Anyone else skip the hot adjustment and just go with a tight cold setting?

3 comments

3 Comments

the_jason1mo ago

My uncle ran a fleet of those old bread trucks with the 4BT engines. He swore by setting them a thousandth loose cold, then never touching them again. Said the hot adjustment just chased its own tail as things expanded. I tried it on my backhoe and it's been fine for two seasons, no clatter. Makes you wonder how much of the old procedure was just tradition.

sarahh481mo ago

My grandpa's farm had a '51 Ford tractor he always tuned by ear in the field. So much of what we call proper procedure is just the first way that worked well enough and got written down. Your uncle had the right idea to question the manual.

terry_bailey3521d ago

I get what you're saying, but I wonder if people make this whole valve adjustment thing more complicated than it needs to be. @the_jason's uncle sounds like he knew what he was doing, but for a daily driver that I depend on, I'd still rather take the time to do the hot check. On my old 12-valve, I've seen guys get too clever and end up with a burnt valve because they thought they could skip steps. A few thousandths either way isn't going to blow the engine, but I've also seen a guy with a six-pack trying to set lash on a Friday afternoon and it turned into a mess. So I say, if it works for you fine, but don't sell the old manual short just yet.