Mechanical Inspection: Compression

Ensure battery is fully charged and starter motor is in good operating condition. On 2.5L, disconnect ignition coil connector. On 4.7L, remove coil-on-plugs. On all models, clean spark plug recesses with compressed air. Remove all spark plugs. Remove fuel pump relay from Power Distribution Center (PDC). See Fig 1 or Fig 2 . Install compression gauge. Hold throttle in wide open throttle position. Using a remote starter switch, rotate engine 3 revolutions. Record compression pressure from third revolution. Continue test for remaining cylinders. See COMPRESSION SPECIFICATIONS  table for correct engine compression pressures.

Fig 1: Identifying Power Distribution Center (Durango)

Courtesy of DAIMLERCHRYSLER CORPORATION

Fig 2: Locating Power Distribution Center (Dakota)

Courtesy of DAIMLERCHRYSLER CORPORATION