One problem related to engine knocking noise has been reported for the 1998 Ford Expedition. The most recently reported issues are listed below.
While driving consumer heard a loud knocking noise coming from the front. The consumer was able to pull over and inspected the vehicle. The consumer noticed that the spark plug from the passenger side blew out. The consumer contacted the dealer, and was informed that the cylinder head needed to be replaced due to a blow out. The consumer found that many others experienced this same problem with the 5. 4 and the 4. 6 Ford engines. The problem was found to be a defect in the heads not having enough threads to hold the plugs in. Ford would not assist in the repair, even though they recently redesigned the heads to prevent the problem.