I have a 2003 ford f-150, 5.4 engine.
I added a pint of some foreign liquid accidently. So I had the oil changed and the filter changed. It's tapping now and the oil gauge in the dash shows low oil pressure.
This the year when Ford made the change on this 5.4 engine with 3 valves per piston and went with VCT system. Variable cam timing. This requires minimum 30 psi oil pressure to operate properly. When pressure drops, you get this diesel engine noise coming out of the heads, specially the passenger side. Check oil pressure with a manual gauge and monitor pressure when cold and see how much it drops as it warms up. If pressure drops below 25psi, you'll start to hear the tapping noise and check engine light will come on telling you there's a problem with cam sensor, when this happens, time for new engine
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