A fleet manager in Toledo told me my valve adjustments were too aggressive

He pulled me aside after a service and said, 'You're setting the intake valves at 0.012 inches, but our engines run hotter on these routes. Try 0.014.' I was skeptical, but I adjusted my process on their next three trucks. Six months later, their callbacks for valve train noise dropped to zero. I've been using his spec on similar highway fleet work ever since. Has anyone else had a customer give them a better spec for a specific operation?

4 comments

4 Comments

jade5172mo agoMost Upvoted

Yeah, that "engines run hotter on these routes" thing is so true. Had a logging outfit tell me to run their diffs a quart over full for the steep hills. Sounded weird, but it totally stopped the whining on long climbs.

the_wyatt2mo ago

Man, the factory specs are more like gentle suggestions once the rubber hits the road. It's like they write them for a perfect world where engines don't actually have to work. Of course the guy who drives the same truck on the same hot road every day knows more than the engineer in an air-conditioned lab. The real manual is written by the guys getting their hands dirty.

phoenixw112mo ago

Totally get that. It's easy to forget that a spec sheet doesn't feel the heat or pull the hills. Those little tweaks from the guys who live with the equipment just make sense. Their fix for the valve noise proves they know their own operation inside and out. You have to respect that kind of real world data.

knight.dylan1mo ago

My buddy runs a small fleet of box trucks out of Phoenix and swears by this one old timer at a local radiator shop. Guy told him to run 5W-40 instead of the 15W-40 the manual says, because the summer heat there makes the thick stuff pour like molasses on startup. He tried it on two of his beaters that were always knocking on cold mornings, and after a few weeks they quieted right down. Now he won't use anything else in the summer months, just says it's the only way to keep those old Cummins happy.