The hard and fast answer to this is that there are no timing marks!!!!! Renault use a cam locking tool that goes on the opposite side to the cambelt. When set correctly, there are two notches in the camshafts that sit just below level to the camshaft cover line. The tool then screws into a hole and locks these two in place. the crank shaft pulley is held by a screw in pin that slots in to h hole by the sump near to piston one. This holds the big end in place and is a bloomin' tricky job because, if you get it wrong, you'll screw into the web of the big end and then it'll slip. Don't, whatever you do, unscrew the campulleys. They have no locating method such as a woodruff key and are purely an interference fit. If you are going to take them off, then draw a marking line on each from the pulley, through the web, onto the camshaft and upto the block.
That having been said, I don't think your problem is the timing as the ecu
would have a fit if the timing was out and the engine is a close intereference job, so your valve would be shot in an instant. I suspect that your turbo
may well be gone as this is a common fault with the DCI. similarly, have you used a diesel flush in it?