The piston of cylinder 1 is set to the TDC (top dead center) position of the compression stroke to ensure that the valve timing is not disturbed when removing the camshaft drive belt.
If the valve timing is disturbed, the engine will not run properly.
In addition, the mark on the camshaft pulley is used to check its position when adjusting the valve clearances, setting the phase of complete closing of both valves of cylinder 1 before adjusting.
Unlike the engines of most other car brands, Renault engines have their cylinders counted from the flywheel, not from the crankshaft pulley.
Set the TDC using the mark on the camshaft pulley (when setting using the marks on the crankshaft pulley, the piston of either the 1st or 4th cylinder can be in this position).
After this, be sure to check that the marks on the toothed pulley of the crankshaft are aligned (with the accessory drive pulley removed).
If the marks on the crankshaft pulley do not match, then the valve timing is incorrect (piston of the first cylinder is not set to TDC).
In this case, it is necessary to remove the camshaft drive belt and turn the crankshaft until they are aligned marks.
To check the alignment of the marks, turn the crankshaft using the bolt securing the accessory drive pulley, removing the upper section of the right engine mudguard to access it.
Alternatively, this can be done in the following ways (especially when adjusting valve clearances, when checking the marks on the crankshaft toothed pulley is not necessary):
Engage any gear (fourth is best) and slowly roll the car until the marks align;
Engage any gear and lift one of the front wheels, then turn the lifted wheel until the marks align.
The mark on the camshaft timing pulley must be aligned with the mark on the cylinder head cover, which is shaped like the Dacia logo, and the mark on the crankshaft timing pulley must be aligned with the mark on the cylinder block.
This becomes visible after removing the accessory drive pulley.
The notch and round protrusion on the timing pulley must align with the recess in the cylinder block.
In addition to the marks on the pulleys, the timing belt has painted notches a, which must also be aligned with the marks on the pulleys when setting the valve timing.
Sam Process
You will need 10mm and 18mm socket wrenches.
Remove the right front wheel.
Loosen the wheel bolts only with the vehicle parked and on the ground.
If you are working on an inspection ditch or overpass, place blocks under the wheels, apply the parking brake, and support the front of the vehicle securely.
Remove the upper right engine mudguard.
Remove the accessory drive belt.
Remove the right powertrain mount.
Remove the five bolts securing the upper timing belt cover.
Remove the cover.
Turn the crankshaft clockwise by the accessory drive pulley mounting bolt until the marks on the camshaft pulley and cylinder head cover.
Then loosen the tightening.
Finally unscrew the pulley mounting bolt.
Remove the pulley.
Unscrew the three bolts securing the lower timing belt cover mechanism.
Remove the cover
Check that the marks on the toothed pulley of the camshaft and on cylinder block cover