19921125 Force SCREW (5/16-18 X 1-1/4") WITH DRI LOC

Illustration 1 g00789241
Section view of a cylinder head with a combustion sensor
(1) Harness connector
(2) Connector
(3) Extension
(4) Sensor
(5) Gasket
(6) Discs Note: Use of a platform may be necessary to reach the combustion sensor.Note: Clean the connections and polish the connections with a clean, dry cloth. Always install a new O-ring seal in connector (1) when the combustion sensor is serviced.
Disconnect harness connector (1) from connector (2). Remove the O-ring seal from the harness connector. Clean the end of the harness connector. Install a new O-ring seal.
Remove connector (2). Clean the inside of the connector's adapters.
Remove extension (3). Clean both ends of the extension.
Pressurized air can cause personal injury. When pressurized air is used for cleaning, wear a protective face shield, protective clothing, and protective shoes.
Note: The maximum air pressure for cleaning purposes must be below 207 kPa (30 psi).
The area around sensor (4) may have debris. Thoroughly remove any debris. Use compressed air. Ensure that the area around the sensor is clean and free of debris.
Loosen sensor (4) with a 15.9 mm (5/8 inch) spark plug socket and an extension. After the sensor has been loosened, remove the sensor by hand in order to detect problems with the threads. If the sensor resists removal by hand, apply penetrating oil to the threads. Use the wrench and apply steady pressure to the sensor until the sensor is loose.
Illustration 2 g00789274
Combustion sensor
(6) Terminal post
(7) Insulator
(8) Shell
(9) Gasket
(10) Electrode
After the sensor is removed, discard gasket (9).
Inspect the sensor closely for damage. Terminal post (6) must not move. If the terminal post can be moved by hand, discard the sensor.Inspect insulator (7) for cracks. If a crack is found, discard the sensor.Inspect shell (8) for damage. Cracks can be caused by overtightening the sensor. Overtightening can also loosen the shell. Discard any sensor that has a shell that is cracked or loose.Inspect electrode (10) for excessive wear.Light brown deposits or beige deposits around the electrode is produced by normal operation. White deposits or gray deposits may be caused by the following substances:
Excessive oil
Use of the wrong oil
A substance that is introduced through the fuel system or the air systemA buildup of ash on the electrode reduces the efficiency of the sensor.
Measure the resistance between terminal post (6) and electrode (10). The sensor must pass a low voltage check for continuity between the terminal post and the electrode. The resistance must not exceed five ohms.
Thoroughly clean the sensor. Clean the shell and the electrode that is inside of the shell. Do not use a wire brush. Glass beads are the preferred method for cleaning. Follow these guidelines for the use of glass beads:
Always use clean glass beads.
Use care in order to clean only the electrode and the insulator near the electrode.
Do not use glass beads on the outside of the shell or on the upper part of the insulator.Ensure that the sensor is clean and free of dirt and oil.Note: Do not use anti-seize compound on the sensor. Most of the heat is transferred through the threads and the seat area of the sensor. The surfaces must be in contact in order to provide the heat transfer that is required.
Place a new 108-3515 Plug Gasket on the sensor. Install the sensor by hand until the sensor bottoms out. Tighten the sensor to 38 2 N m (28 2 lb ft).
Install extension (3). Make sure that discs (5) are positioned in order to align the extension's connectors with sensor (4) and connector (2).
Make sure that the O-ring seal on connector (2) is in good condition. Install the connector.
Attach harness connector (1) to connector (2).