Sounds like a 306 diesel.

My car is 306 1.8 16v. I changed the timing belt this week. After the change, the sound of my car changed. If I listen without opening the hood, there is no problem, but when I open the hood, the vehicle obviously works like a diesel.

The mechanic said the gasket was gone, we had to remove the cylinder head. But I can't fully trust him because of a few events I've had before.

What do you think is the reason for this?