Checking and setting the TDC of the first engine cylinder in the compression stroke is necessary when performing work on removing the camshaft drive chain
It should be taken into account that when installing according to the marks on the crankshaft pulley and the oil pump housing, the piston of both the first cylinder and the piston of the fourth cylinder can be in this position
There are no marks on the camshaft sprocket. There is only a groove on the front end of the camshaft, by which you can determine that the camshaft is also in the TDC position.
In order to determine in which of the cylinders the compression stroke is, you need to remove the cylinder head cover, check the ease of movement of the rocker arms of the valves of the first and fourth cylinders, or remove the timing disk of the phase sensor to determine by the position of the groove in the rear end of the camshaft.
After this, you need to make sure that the marks on the crankshaft pulley and the oil pump housing match.
If the marks do not match, then the valve timing is incorrect.
In this case, you need to loosen the camshaft sprocket mounting bolt and, with the camshaft position unchanged, turn the crankshaft until the marks match.
Turn the engine crankshaft until the marks on the crankshaft pulley and the oil pump housing match.
Fix this position of the crankshaft by inserting a pin with a diameter of about 6 mm into the hole.
The crankshaft can be turned by the flywheel ring gear.
To do this, remove the plug from the hole in the flywheel housing
Rotate the flywheel by the teeth of the crown with a large screwdriver, resting it on the edge of the hole
Removing the vacuum pump
Checking the position of the groove in the front end of the camshaft for the tailstock of the vacuum pump shaft.
The groove must be located strictly vertically.
To determine, in in which cylinder the piston is at TDC of the compression stroke, remove the head cover
Try to swing your hand on the axes of the rocker arm "A" of the valve drive of the first cylinder and the rocker arm "B" of the valve drive of the fourth cylinder.
In the cylinder, both rocker arms of which move freely, the piston is at TDC of the compression stroke.
To restore the correct valve timing, you need to remove the engine, since access to the valve timing drive on the car impossible.
On the removed engine, in order to correctly set the valve timing, we remove the locking pin, which was installed from the holes of the crankshaft pulley and the oil pump housing.
We turn the crankshaft in the required direction until the groove on the front end of the camshaft is set to the correct position.
We fix the camshaft in this position using a device
Figure 8 shows a device for fixing the camshaft.
Unscrew the five bolts securing the timing case cover
Remove the cover
Holding the camshaft from turning by the holes in the timing disk of the phase sensor, loosen the tightening of the bolt securing the timing disk and the camshaft sprocket.
Turn the crankshaft until the holes in its pulley and the oil pump housing coincide and tighten the bolt securing the timing disk and the camshaft sprocket.
If it is necessary to determine on a removed engine, in which cylinder is the TDC of the compression stroke, this can be done without removing the cylinder head cover.
Fully unscrew the bolt securing the timing disk of the phase sensor
Remove the disk
After removing the disk, a groove on the rear end of the camshaft becomes visible, which will be directed strictly downwards if the piston of the first cylinder is at the TDC of the compression stroke.