If the gap is too small, the valve timing changes, compression is worse, engine power drops, engine operation is uneven. In extreme cases, the valves may be damaged or the seats and valves may be burned.
If the gap is too large, strong mechanical noises appear, the valve timing changes, the engine delivers less power due to insufficient filling of the cylinders, and the engine runs unevenly.
Valve adjustment only achieves the desired result if the valves seal perfectly, do not have unacceptable play in the guides and the ends of the rods are not knocked down.
The valve clearance must be checked and adjusted after repair, if noise appears in the distribution mechanism. It is not necessary to check the valve clearance as part of maintenance. The 2.0L diesel engine has hydraulic tappets that automatically select valve clearance. These engines do not have adjustable valve clearance. If there are unusual noises in the valve mechanism, check the hydraulic pushers (performed in the workshop).
Valve clearance should be checked or adjusted when the engine is warm, but it can also be adjusted when the engine is cold. In this case, it will need to be checked on a warm engine.
Verification conditions
1. Start the engine and warm it up until the coolant temperature reaches 80°–90°C.
2. Stop the engine.
3. To facilitate the work, remove drip candles.
4. Unscrew the cylinder head cover.
5. Set the transmission to neutral, apply the handbrake.
6. Set the piston of the 1st cylinder to the TDC position.
7. At the same time, the 4th piston is in the TDC position. Cylinders are counted from right to left. Cylinder 1 is on the V-belt side of the engine.