Hello, I have a 1990 F-150, 5.8 V-8 that is tapping very loud. I have used sea foam and changed the oil. No help. I checked the pushrods, all appear straight. I replaced the lifters (hydraulic). No help. New exhaust system from manifold back. No help. The oil pressure shows good. The tapping does not go away when vehicle warms up. The tapping continues/increases as rpm's increase. Truck runs good, does not miss and plenty of power. Any help or ideas so that I can diagnose this problem?

 

Can you if possible tell if it is louder on one side than the other? Usually when we use "tapping" it is coming from the valve train.
I know this isn't going to be easy , but can you confirm if the oil is coming up through the pushrods ? You can usually see the oil running down the pushrods at idle. If all are getting oil, could what you are calling tapping be more like a rapping in which case it could be a bearing rap ? The way to determine which cylinder is causing the bearing noise is found by shorting out each individual cylinder spark plug and the plug that makes the noise less is the cylinder with the questionable bearing. Whatever you do don't remove the spark plug wire when its running because that puts a terrific load on the ign module and could damage it.

 

the noise appears to be coming from the passenger side. i often wondered if i am getting enough oil up to lifters, rods etc. it seemed when i pulled it apart that there was not as much oil as i normally see on other valve cover removals. does that make any sense??? my oil pressure guage on the dash shows in the normal range, but i am not sure how to check the pressure. i considered putting longer rods in but am unsure if that is the problem. i hate to keep taking this apart and just replacing parts and putting back together and taking it apart etc. i also thought perhaps my manifold is cracked. any suggestions are very much welcomed.