I just finished rebuilding my engine, a 1998 4.6l. Anyway I primed the hydraulic lash adjusters properly, all of them new by the way. Started the engine and was getting a diesel like tapping noise from the right bank only. Thought their might be some air that got in the lash adjusters from when the oil system primed. Oil pressure is steady, runs like a bat out of hell too. The tapping dissappears when above 1100 rpm, seems to get progressively worse as the engine warms up. It has been driven for about ~40 miles since initial startup. I looked through the fill tube while the engine was running and the oil is being spread just fine. Pulled injector electrical connectors to try and determine whether it was the injectors, it isn't. So thinking that my assembly lube may have already thinned the 5w-30, I drained it and replaced with 10w-40 and Lucas Oil Treatment, the noise has all but disappeared, not tapping nearly as loud, yet still doing it? Does it normally take this damn long for air to work it's way out of lash adjusters even after priming them assuming that air from the oil paths in the block has gotten into the lash adjusters? Ideas? Jesus I need to get this **** fixed.

 

i hope somone answers because my 97 4.6 started making the same noise at 150000 and comes and goes. maybe it is something that is fairly common?

BTT