Knock

Hello,
I have an 89 ford f-150 extended cab long bed 4x4 pickup with the 5.0 and I have been noticing a knock lately.

It knocks at start-up for about 3 seconds and then nothing, then at about 1900 rpm it becomes audible again all the way through the rpm range.

Tom

double knock like a piston pin or deep single knock like rods or mains? Or something else? Noticed anything in your oil changes?

Nothing in Oil during changes. More like a single knock like rod or mains, but with a stethescope I hear nothing at idle and I am having trouble locating the culprit. This morning i started it up and usually i have know at first start up, but this morning i had nothing it was smooth.

Do you think maybe it is the belt tensioner or the power steering pump?

Tom

could it be a flex plate cracked i have seen this on chevy were it sounds like a rod or main

Second that one, I have seen this too.