Cylinder heads were fixed and lifters were checked and fine?

Question

EVERYONE IS TELLING ME THAT THE TAPPING NOISE MUST BE THE LIFTERS, BUT WHEN I ASKED MY MECHANIC HE SAID HE CHECKED THE LIFTERS AND THEY WERE FINE. ANY OTHER SUGGESTIONS. 98 LINC NAVIGATOR.

Answer 1

This might sound like a dumb question, but what GRADE and BRAND of gasoline are you using? Your '98 Navigator is equipped with the 32-valve 5.4L V8 which REQUIRES 91 octane gasoline. If you use ANYTHING LESS, your engine will PING!!! The noise you are hearing, is probably the valvetrain "crackling", or "tapping" when you accelerate, or put the engine under load. What I just described is PINGING, which is caused by using less than the required octane level. If this is the case, use up ALL the gasoline AT ONCE, and refill using the proper gasoline from now on. Continued operation with the wrong grade will have a DETRIMENTAL effect on the pistons, connecting rods, and other parts in the engine. YOU DON'T WANT TO DO THAT. We're talking BIG dollars if you destroy the engine in your truck. The required octane rating should be shown on a label on the inside of your fuel filler door. Hope this helps.

Answer 2

change your oil to 15W40 (Quaker State) The valves may need re-adjusting or the camshaft is faulty. Is the "Tapping" noise coming from the top of motor? is sufficient oil getting to the top of engine?
Putting in a thicker oil should quiet down an engine.

Answer 3

I am willing to bet that you have an exhaust manifold leak, very common in the 5.4L, and more than likely a broken exhaust stud also. Take it to a DEALER and have them check it over.

Answer 4

The fuel injectors also make a clicking noise, but it is so faint that you cant hear it inside the drivers compartment. Tell me more.

Answer 5

Could be a rod bearing going out, it IS almost 10 years old.