Cylinder Block Assembly: Service and Repair
Determining the operating cycle of cylinder 1Information
ATTENTION: Risk of damage to timing drive mechanism!
^ Never twist the crankshaft against the direction of rotation.
^ Remove and install the chain tensioner only in overlapping TDC.
^ Never twist the crankshaft when the chain tensioner is removed.
^ Never twist the camshafts when the chain tensioner is removed.
^ Never apply forces across the camshafts in the timing drive mechanism.
^ Always counter the sprocket wheels when performing assembly work on them.
--> Forces from the valve drive can cause the timing chain to jump over or tilt.
Note:
^ All spark plugs (except for those on cylinder 3) must be removed to ensure that the relevant dead centre can be found more easily.
^ The torque support bracket can remain in place.
Note: An alternative method for determining the overlapping TDC is the "cylinder pipe" (dead centre finder). This tool is part of the pressure-loss tester WE 1066, Workshop Installation Manual 3.1.4.
For some tasks, it is necessary to be familiar with the position of the piston in the cylinder (ignition TDC, overlapping TDC).
Ignition is off, ignition key is removed.
Spark Plugs:
1. Remove spark plugs (except those on cylinder 3). --> '287055 Replacing spark plugs'
Compression cycle for cylinder 1 (ignition TDC)
Ignition Rod Module Of Cylinder 1:
1. Find ignition TDC of cylinder 1. To do this, insert the ignition rod module of the first cylinder into the corresponding opening in the valve cover and press in firmly.
Ignition Rod Module Of Cylinder 1 Pops Out:
2. Twist the crankshaft in the direction of motion until the ignition rod module comes out again with an audible plop.
TDC Marking Of Cylinder 1:
Note: If the crankshaft is then turned through 180°, the piston in cylinder 1 will be located in the bottom dead centre (BDC). The emission cycle then follows.
3. Then twist the crankshaft until the fixing bore on the crankshaft belt pulley is aligned with the bore in the timing case cover. The engine is now located in the ignition TDC of cylinder 1.
Intake cycle (overlapping TDC)
Ignition Rod Module Of Cylinder 1:
1. Find overlapping TDC of cylinder 1. To do this, insert the ignition rod module of the first cylinder into the corresponding opening in the valve cover and press in firmly.
Ignition Rod Module Of Cylinder 1 Pops Out:
2. Twist the crankshaft in the direction of rotation until the ignition rod module comes out again with an audible plop.
TDC Marking Of Cylinder 1:
3. Then twist the crankshaft until the fixing bore on the crankshaft belt pulley is aligned with the bore in the timing case cover. The engine is now located in the ignition TDC of cylinder 1.
TDC Marking Of Cylinder 1:
Note: If the crankshaft is then turned through 180°, the piston in cylinder 1 will be located in the bottom dead centre (BDC). The compression cycle then follows.
4. Remove the marking mandrel if necessary and twist the crankshaft through 360° in the direction of motion. The engine is now located in the overlapping TDC of cylinder 1.