- A set of probes with a resolution of 0.05 mm.
- A piece of wire about 2 mm thick (or thin drill).
- A set of wrenches and a set of heads.
The following wear parts are required:
- Cylinder head cover gasket.
To compensate for thermal expansion in the valve actuator, a certain clearance must be provided between the camshaft lobes and the valves or rocker arms. Valve clearances change over time due to valve settling and valve train wear.
If the gap is too small, the valve timing changes, compression worsens, engine power decreases, the engine runs unevenly. In extreme cases, valves can be deformed or valve seats burned. With increased clearances, strong mechanical knocks occur, the valve timing changes, due to a decrease in the valve opening time and thereby deterioration in cylinder filling, engine power decreases, the engine runs unevenly.
Checking and, if necessary, adjusting valve clearances should be carried out on all engines except models 518i, 525td / tds, 520i / 525i manufactured from May 1990 according to the indication of the service interval indicator or as part of maintenance every 20,000 km. The mentioned engines have hydraulic valve clearance compensators and do not need to be checked or adjusted.
Examination
Checking and adjusting valve clearances is carried out both on a cold and on a warm engine.
Remove cylinder head cover.
There are two possibilities for turning the engine to the desired position. The first, most simple option: turn on 4th gear, release the handbrake. Move car.
The second option: move the gear lever to neutral, tighten the handbrake. Turn the engine at the central bolt of the belt pulley.of the crankshaft with a 27/30 mm socket on it, clockwise (motor rotation direction). This also rotates the camshaft.
It is advisable to start the test with the valves of the 1st cylinder, setting it to the top dead center position. The 1st cylinder is located at the front of the engine. After that, the engine turns over (on a four-cylinder engine, half a turn) and check the valves of the next cylinder according to the ignition sequence.
Ignition sequence on a four-cylinder engine: 1-3-4-2; on a six-cylinder engine: 1-5-3-6-2-4.
Another option for adjusting valve clearances: turn the engine to a position in which, for any of the valves, the camshaft cam is facing away from the rocker arm of the valve being checked, and the cam is adjacent to the rocker arm of its generatrix. The illustration shows a petrol engine, on a diesel engine the cam must be moved away from the rocker arm. In this position, measure the valve clearance and adjust if necessary.
Mark the rocker with a felt-tip pen.
Move the car a little more until another cam moves away from the rocker arm. In this case, the sequence of adjusting the valve clearances is indifferent. The rocker arms are marked so as not to double-check the valve clearance by mistake.
Petrol engines: Measure the valve clearance with a feeler gauge F inserted between the eccentric E and the end of the valve stem.
524td diesel engines: Measure the valve clearance with a feeler gauge F between the cam and rocker arm.
The valve clearance is set correctly if the feeler gauge is tight.
To sample, take a probe over the specified size See Table 1 by 0.05 mm. It should not go between the valve and the rocker arm. If it passes, reduce the valve clearance.
Table 1. Valve clearances
Attention: The specified clearance values for intake and exhaust valves are the same.
"cold" the engine is called when the coolant temperature is below +35°C. To adjust valve clearances "warmed up" engine coolant temperature should be around +80°C. The symptom is a warm lower radiator water hose. The thermostat just opens a large coolant circuit.
Adjustment
(Drawing W - 6266) If the valve clearance differs from the specified value, insert the BMW 113070 rod into the hole of the eccentric E, loosen the nut and turn the eccentric with the rod until the specified valve clearance is reached. If a BMW tool is not available, a thin screwdriver of the appropriate diameter can be used.
Tighten locknut to approx. 10 Nm (estimated value), while holding the eccentric. Check the valve clearance again and crank the engine further. In the same way, check or adjust the clearances of the remaining valves.
Install the cylinder head cover.