To align the marks without tools, you can use a screwdriver or other small object to insert into the spark plug hole. When the screwdriver is at the highest point of its travel, the engine is at TDC. You can then align the marks on the crankshaft and camshaft pulleys.
Here are the step-by-step instructions on how to align the timing marks on a 19D Citroen engine without tools:
1. Remove the spark plug from the engine.
2. Insert a screwdriver or other small object into the spark plug hole.
3. Turn the crankshaft pulley until the screwdriver is at the highest point of its travel.
4. Align the marks on the crankshaft pulley and the camshaft pulley.
5. If the marks are not aligned, turn the crankshaft pulley one full revolution and try again.
6. Once the marks are aligned, reinstall the spark plug.
It is important to note that aligning the timing marks is essential for the engine to run properly. If the marks are not aligned, the engine will not be able to start or run smoothly.