Sorry for the repost, but I think I posted to a dead thread - so here goes again.
I got in my explorer one day and the thing just started ticking at 95K miles (parked on a steep hill like MichaelF described, hood pointed down) From that day on, and for the past 3 years, I hear about 3 of them (lifters) ticking. They tick in a kind of cycling pattern. It will tick progressively louder for several seconds then stop for several seconds. This cycle repeats - like the oil is getting pounded out of them, then suddenly, they refill or unstick. As the engine warms up, they get better, but still tick. One thing I came across on message boards for another engine is the possibility of a spun cam bearing, partially obstructing the oil to the lifters. Does anybody know if the oil for the lifters on a 1991 4.0 goes through the cam bearing(s), or can leak enough to kill the pressure to the lifters? I tried motor flush, and it actually sounds better while I'm running the flush, but the ticking returns as soon as I refill with regular oil. This leads me to believe that there is some kind of obstruction in an oil passage. I refuse to believe that I had 3 lifters go "bad" in one day, all at the same time.
I got in my explorer one day and the thing just started ticking at 95K miles (parked on a steep hill like MichaelF described, hood pointed down) From that day on, and for the past 3 years, I hear about 3 of them (lifters) ticking. They tick in a kind of cycling pattern. It will tick progressively louder for several seconds then stop for several seconds. This cycle repeats - like the oil is getting pounded out of them, then suddenly, they refill or unstick. As the engine warms up, they get better, but still tick. One thing I came across on message boards for another engine is the possibility of a spun cam bearing, partially obstructing the oil to the lifters. Does anybody know if the oil for the lifters on a 1991 4.0 goes through the cam bearing(s), or can leak enough to kill the pressure to the lifters? I tried motor flush, and it actually sounds better while I'm running the flush, but the ticking returns as soon as I refill with regular oil. This leads me to believe that there is some kind of obstruction in an oil passage. I refuse to believe that I had 3 lifters go "bad" in one day, all at the same time.
