Well, trucks been running so good I was bound to eventually have a problem. So went out this weekend and for the first time since I bought it a year ago, engine is knocking/tapping when cold. It sounds to me like a lifter is not filling and expanding. Once it's warm, as I drive it, knock/tap disappears. Once cold it does it again.

Also, I've noticed my oil light stays on for no more than 2-3 seconds after I start it cold and then builds to normal pressure. I don't know if the two issues are related as the slight delay of pressure has been doing it for a while while the knock/tap just started this weekend. Engine is 360 fe all stock except headers. Runs great, does not burn oil, etc.

Wondering if I'm dealing with lifter (it sounds like a single knock), piston slap, exhaust leak, or something deeper. Could it be oil pump is failing or something there is clogged? If it was oil pump I would assume I'd hear more than a single knock. Again, onceengine warms up knock/tap goes away and only returns when truck's been sitting again a long time. I ran a mechanical oil gauge recently and the pressure looked okay with no wild fluctuations at various RPM's.

My other question is what to do temporarily until I can dig into engine, either below if oil pump is worn out or above if I need to deal with valve train, etc. I've heard some people have had results with changing oil, and adding Lucas in place of one of the quarts. Others say they've had results with Seafoam to release a sticking lifter.

Any thoughts and temp remedy ideas would be appreciated...

 

It could be anything you suggested based on your description . as a rule a tap is in the top end and a knock is in the bottom end.

The first think I'd do is get a mechanical reading on the oil pressure.

 

I'm pretty sure this would be classified as a tap. I haven't put a steth on it at this point, but it sounds like a top-end tap. Yeah, I'll run the gauge again toi see if it changed from readings I got about a month ago.

 

Do yourself a favor and check all the bolts on your headers too.

 

if it's in the top end and it's not an exhaust leak then chances are good that you're hearing slack in the lifter preload. when it warms up the expansion helps a bit and maybe the lifter pumps all the way up.

if your suspicion of low oil pressure is correct that would add to the problem . so checking it is certainly worth while.