I have a 97 Expedition, 4.6L. Recently, the engine started tapping/rattling like crazy. I got an oil change. They ran a cleaner additive through and gave me the high-mileage oil to help swell the seals. (It has about 185,000 miles, BTW.) That worked for a couple of weeks.

Now the tap/rattle is back. It sounds basically like a diesel engine. My suspicion is a timing chain problem. Any advice?

 

No no its not the timing. Put 5W-30 Mobile 1 synthectic with a quart of lucas oil treatment. Change fuel filter and put some Techron fuel injector cleaner with some high grade fuel in it. Then run the h*ll out of it for a while. SOunds like injectors to me so give it a try.