Hey Everyone, I've got an 03 5.4 that started knocking/ticking from what seemed like the driver's side top end. I pulled the valve cover and I don't see anything super obvious. I took out the front rocker arm and lash adjuster and I was wondering, how do you tell if these have gone bad? The truck has been sitting for about a week without running, so id assume lash adjuster should be limp. After pulling the adjuster i can grab the tip and move it about 1/16-3/32" easily, which I would think is okay without oil pressure. Is that normal? When I cover the small hole in the side of the adjuster with my thumb, it does spring back when i easily push it down by finger.

 

I would check to see if you have a spark plug that’s backed out of its threads. Mine made a ticking/knocking sound, what I thought was top end noise. About 600 miles later my truck ejected a spark plug on a mountain hwy going about 60mph. Scared the s*** out of me. Just a thought..

 

That was the first thing I checked. All appear to be tight.

 

Bad lash adjusters sound nothing like a loose spark plug. More prevalent at cold start. Yea, there's no mistaking lash adjusters. The old 98 5four adjusters got loud around 280,000 miles. It's at 360,000 miles plus currently, still loud when cold. Haven't changed them out. Truck is about rusted out, that's the only thing wrong with it besides noisy lash adjusters.....sitting in a field, used occasionally. Starts every time and runs well...it'll be hauled away if that ever changes. That thing just won't die lol.

Replace them if it's worthy.