Greetings,

I purchased my 2008 Explorer Ltd about 4 months ago with a 4.6L and 63k miles. I use it for towing a small travel trailer, so I don't put many miles on it. It's got about 66k on it now. According to OASIS, it has had all MFR maintenance performed up to the 60k mark.

In the past two months, it has developed a "sound" on startup. it goes away after about 75 seconds. To me it sounds like a typical exh manifold leak. That "3 cylinder, putt putt putt tractor" sound. There is no apparent affect on performance. It is definitely coming from the area of cyl #1. I have a recording here.

https://picasaweb.google.com/1039561...eat=directlink

It is the "higher" of the sounds. The lower pulsing/whooshing is just regular engine noise. You can hear the regular engine noise as the camera pans to the back of the car.

What puzzles me is that the exh manifold sound goes away after 75 seconds or so. Holding the tailpipe shut for a bit builds up lots of pressure quickly. Do you think it IS in fact an exh manifold leak, and it seals up with thermal expansion as the engine worms up (75 seconds)? Is this a typical issue with the 4.6L

Thoughts, comments suggestions?

Thanks.

Paul.../NH