I own a 2004 Explorer Eddie Bauer Edition with 182,000 on the clock that has developed a very annoying engine rattle. The rattle started just shortly after having some service done on the truck. I had the P/S, Brake, Transmission and Rear diff fluids replaced. I also had the A/C system evacuated and recharged along with replacing the A/C manifold line and rack and pinion. The noise is most noticeable at first start and goes away when driving. I took it to Ford and they said that the timing belt tensioners were bad so they were replaced, but the noise was still there. Then they replaced the serpentine belt tensioner and pulley, but again noise is still there. I refused to have Ford do any more work since I had already been charged almost $1500 for repairs and the problem was not fixed. They said the next thing would be the balance shaft or rebuild the engine. The truck runs fine, smooth and does not shake at idle. It just has this awful noise. I have tried other forums with no luck so I am hoping someone can help me identify this issue; here is a video of the noise. Any help would be great.
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Are you sure it is not a loose heat shield rattling underneath your truck. I have an 04 sport trac that rattled like crazy at idle, drove me crazy. so I went under my truck and ripped it of. No more rattling...
Anyway, just my two cents, hope it helps.