Additionally, it is recommended to purchase a special clamp, for example, HAZET 1849, which facilitates the removal of spark plug tips. The following parts must be purchased for replacement: Depending on the number of engine cylinders, 4 or 6 spark plugs, respectively. Standard spark plugs are listed on p. 52.
Caution: Removing spark plugs for engines from 9/94 see p. 51.
Removal
Engines up to 8/94
Remove the spark plug tips from all spark plugs, pulling only the tips, not the wires. The special clamp mentioned above makes this operation easier.
If possible, blow out the spark plug recesses with compressed air to prevent dirt from penetrating the threaded holes into the cylinders when the spark plugs are removed.
Remove the spark plugs with a spark plug wrench and check their condition. Some experience allows you to draw conclusions about the operating condition of the engine based on the appearance of the spark plugs. The following rules apply here.
Electrodes and insulators:
- are grey in colour - correct operation of spark plugs and correct composition of the combustible mixture
- are black in color - the combustible mixture is too rich
- are light gray in color - the combustible mixture is too lean
- oily - misfires in the corresponding spark plug or poor sealing action of the piston rings (check compression)
Examine the spark plug insulators for signs of current leakage. Current leakage appears as thin, uneven marks on the outer surface. If signs of current leakage are found, check to see if the spark plug tip is cracked and replace the tip if necessary.
Installation
Using a feeler gauge, check the distance between the spark plug electrodes.
New spark plugs usually have the correct distance between the electrodes, see p. 52.
The gap between the electrodes is adjusted by bending the ground electrode. There is a simple and practical tool for this. If you don't have one, you need to tap the ground electrode from the side. When bending the electrode, use a small screwdriver to rest on the edge of the threaded part of the spark plug, but never on the central electrode, as this will damage it.
Clean the spark plug threads with a clean cloth.
Screw the spark plugs into the cylinder head by hand until they stop.
Note: Do not tilt the spark plugs.
Tighten the spark plugs to the appropriate torque. Spark plug tightening torques: ONS engine - 25 Nm; dOHC engine - 20 Nm; v6 engine - 40 Nm; 2.9L V6-24V engine - 30 Nm.
Install spark plug caps according to the firing order of the cylinders. Firing order for a 4-cylinder engine: 1-3-4-2; the firing order for a 6-cylinder engine is: 1-4-2-5-3-6.
Check the strength of the fit of the tips and high-voltage wires by rocking them in different directions.
Checking electrical connections
Check the reliability of all electrical connections at the ignition coil and at the ignition distributor.
Replace cracked terminals.
Remove the distributor cap and wipe it with a clean cloth inside and out.
Clean rusty contacts with a wire brush or file, and spray with contact spray if necessary.
The contacts should not be wet, if necessary spray them with contact spray.
Bend high-voltage wires with a small radius by hand and make sure there are no cracks in the insulation. If there are cracks, replace the wires.