Engine dry, tappet noise but plenty of oil??

[caddydaddy]

Hey guys, me again, ok, newish rebuilt motor 390, 2 years old 30,000 miles on the clock driving down the freeway for 40 minutes, between 60- 65mph, start start slowing down start to hear like dry tappet sound coming from motor, get into suburbs to find petrol station to pull up, noise slowly goes away, no heat change, check oil, is full, what the? Remembered back to a few months ago, same sound, check oil, oil is black, changed oil and filter, all good now. Oil is still clean now, but noise comes only if i do hwy speeds for a while, new oil pump kit maybe? Anyone with an idea? Regards CaddyDaddy

[Ronald]

With the lifters making noise - pull the dip stick and look for bubbles or foam.  Maybe the oil pickup is too high and sucks in air at high speed.

Oil pump not tight to the block - sucking air?

Air is likely the problem or cam is going flat and everthing is just borderline working.

Ron

[EZ]

I have heard reports of cheap Chinese lifters being sold in rebuild kits.  Maybe you have a lifter going down?  The only way to determine if you have oil pressure is to run a temporary oil gauge to where the oil sending unit is located.  This will either confirm the oil pump is the problem or eliminate it from your worries.  If it's not the oil pump I'd look at the lifters.