I?ve got a 95 5.7 L Chevy Box truck (FI), only about 50k miles
Runs great all day on local roads, but as soon as it?s on the highway (over 55 mph) for a few minutes, the lifters atart to rattle.
There is no drop in oil pressure, and the oil I?ve changed the oil every 1,000 miles three times.
Once it?s off the highway, a few miles later it?s back to normal.
There is no drop in performance, so it must be a lifter that collapses when it gets hot?
Any ideas/suggestions?