Removal
Cool the engine.
Remove all spark plug caps by grasping the cap, not the cable. A special grip, such as the HAZET 1849, will make the job easier.
Clean the spark plug recesses, if possible, with compressed air.
Unscrew the spark plugs using a special key.
Examination
Check the appearance of the spark plug. It can be used to draw conclusions about the engine condition. The following rules apply:
Electrodes and insulator body
- Gray = carburetor adjustment and spark plug operation is correct
- Black = Mixture too rich
- Light gray = Mixture too lean
- Oily = spark plug protruding or piston rings not fitting tightly
Clean the spark plugs with a brush or sandblast.
Check the spark plug insulators for surface leakage currents. These appear as thin, irregular marks on the surface. If the leakage current marks are not eliminated, the spark plug should be replaced.
Check the spark plug gap with a feeler gauge. If not, replace the spark plug.
Installation
Clean the threads on the spark plug and in the cylinder head.
Screw the spark plug in by hand until it stops.
Attention: make sure that the candle does not become crooked.
Tighten the spark plugs to the required torque.
Caution: If a torque wrench is not available, new spark plugs with a flat seal "A" should be tightened 90° (¼ turn). Spark plugs with a conical seal "B" should be tightened 15°. as well as used spark plugs with a flat seal. Spark plugs that are tightened too much may burst when unscrewed or strip the threads in the cylinder head.
Install spark plug caps in firing order Check that caps and cables are securely seated. Firing order for 4-cylinder engines: 1-3-4-2; 5-cylinder engine: 1-2-4-5-3. On the distributor cap next to the output of the first cylinder there is a mark, then follow in the direction of rotation of the runner for a 4-cylinder engine the ignition cable of the 3rd cylinder, then the 4th cylinder, etc. The direction of rotation is shown as an arrow on the distributor cap. If there are no marks on the cover, remove it together with the boot. On the edge of the distributor there is a notch, above it with the cover installed is the output of the 1st cylinder. With the distributor cap removed, turn on the starter for a short time and determine the direction of movement of the runner. The cylinder numbers are counted from the front (toothed belt) back (flywheel).
The article was copied from the website audimanual.ru