peugot 307 2.0hdi 90 timing belt?

Yes, perfectly normal, the play is supposed to be there for fine tuning the valve timing, do not use "magic metal" as previously suggested.
Special tools are supposedly required to change the belt but they are only useful if the engine has lost it's timing, if you're just changing the belt mark the old belt and pulley wheels, duplicate the marks on the new belt and fit it exactly as the old belt came off.
It perhaps goes without saying but lock the crank and cam shaft before marking or taking the old belt off. There are location holes, one in the cam pulley wheel and one that locates in the flywheel, you'll find this one from under the car, it's just under the starter motor.
When the new belt is on fit the bottom timing cover and tighten the bottom pulley wheel a little, not too much as you'll bend or break your crank locking pin. Once nipped up take the pins out, get a friend to sit in the car with it in gear and his foot on the brake, now tighten the bottom pulley up properly.
Once tight rotate the engine by hand a couple of time then make sure your locking pins for the cam and crank still align correctly, if they don't repeat the above steps.

Lee
January 2013

Was the motor running ok before you stripped it down?if so then I take you are on about a small amount of play in the gear and woodruff key,I would have a close look at both key and gear and make sure neither are worn excessively,you could maybe take up that play with a smear of magic metal when you build it up and leave it overnight so that it sets up good before running it.Another thing to check is the crank pulley on these which are bad for causing a knocking,any doubt replace.Good luck

cdc
September 2012