I have been getting some lifter noise and on hot days not every time,but when I started after driving around I would get the lifter noise.I never got it from COLD/First starts just starts after being driven awhile.
I did smell a light antifreeze odor so I opened the radiator and WOW It was almost black looking.I flushed the whole system twice.To the point there was all clear water.I was told that the intake can leak water onto the lifters and wash the oil off causing the lifter noise.Could it be the oil cooler is not cooling the enough on hot days or when it's running to cause the same noise?
NOW I'M WORRIED. Any suggestions would be nice.
Oh.170,000 4.3 ltr.

 

Its an unusual problem, but the intake manifold gasket seems to have failed and is leaking coolant into the lifter valley. I'd get the intake manifold gasket changed and the oiling system flushed out.