1998 Ford Expedition 4X4 4.6L, the poor quality steel used for the exhaust manifolds and bolts rust very fast. Mine resulted in the driverside bolts rusting away causing exhaust coming directly out of the engine, also the egr tube rusted off the drivers manifold causing hot exhaust to blow toward the top of the engine. On the passenger side the manifold bolts/studs also rusted away causing exhaust to disperse in the engine bay. Also on the passenger side the manifold cracked about 3 inches long on the top of the manifold causing hot exhaust to blow upward to the upper engine bay. I corrected this problem by replacing the bad manifolds/studs with pacesetter shorty headers and bolts, it was the cheapest fix. The pacesetter shorty header kit was $150 from www.summitracing.com. the truck was extremely loud before I fixed this problem and I was pulled over for it by the police 4 times, they let me go if I promised to fix the problem. Since I fixed the problem the truck is very quiet and I don't get threatened with $75 tickets anymore plus I have the peace of mind the truck wont burn to the ground with my family in it from hot leaking exhaust manifolds or rusty failed studs/bolts.

- Braidwood, IL, USA

On the underside of the vehicle there is an audible, high frequency rattle or vibration that is increased when the vehicle is in gear, stopped and in idle. The noise reduces and often goes away when the engine rpms are increased above 600 per minute. The vehicle has been examined by the dealer three times, has had all of the exhaust brackets tightened or replaced to no avail. Owner was informed that it was a "backed out bolt in the exhaust heat shield", this bolt was changed by dealer on the 3rd trip, with no change, in fat, that made it worse. Two different muffler shops have looked at and notice nothing else loose or missing. On the last visit to the dealer, owner was told that the reason for the noise is that the "exhaust pipe is torqued and twisted a little bit from heat contraction and expansion."

- Gulfport, MS, USA