After having a tappet bearing go out and finding fillings in the oil filter I replaced all 4 tappet bearings, took the tappets apart and cleaned them,tore down the oil pump, cleaned all oil hoses, blew out tappet blocks etc. but than the back tappet would start making a loud noise after 6 miles out every time but would quit making noise after I pulled over for a minute than all would be well. So I replaced the back complete tappet and the noise ceased but than one of the front tappets started making major noise at about 10 miles out every time funny cause I never pulled the front tappet block etc. I'm thinking since I have normal oil pressure that I must have fillings from the old bearing plugging up an oil passage some where ?? Anyone have any thoughts as to fixing my problem ?

 

1988 or 88in power plant

 

Did you clean the lifter filter screen as well? Oil tank?
Did the pump body or feed/scavange gears get buggered?
Also a service bulletin that came down from the Moco back in the Evo days mandated that the lifters be "inspected and/or replaced at 25,000 miles."
Scott