Ticking at Idle

[Justin e]

Have a 1998 gmc k1500 With just over 44,000 On the clock. Motor wasn't maintained in its early years so there was some issues with sludge build up but the engine has been flushed out a couple times and that issue has been remedied. However at idle im getting a ticking. No issues with the oil pressure or what RPM its idling at. But it's got what sounds like a rocker tick. anyone else had this happen on this low mile of motor. And yes it is the original motor.

 

[Schurkey]

Hydraulic lifters are like tiny oil filters. The passage for oil to get into the lifter is fairly huge compared to the passage for oil to get OUT of the lifter, which is microscopic.

Any contamination in the oil during the "flush" may migrate to the lifter interior. The lifters have to come apart to clean 'em out, and that's assuming that the lifter guts aren't scored or otherwise damaged by the debris.

'Course, you could have other problems than lifters. Broken valve spring, exhaust leak, injector tick, crankshaft hitting the dipstick, and broken flexplate all come to mind.