BMW Repair Questions? Ask a Mechanic for Answers ASAP
yes a stretched or loose timing chain will effect the cam timing and its possible for it to get that bad you will start to get misfires
especially if you have a tinkling / rattling noise
if you were to do a compression test across all cylinders this will show if the timing is out as they should all be within 10-15 psi of each other
and at this millage its not uncommon for a new chain to be required
so if you are planning on keeping the car then I'd say that a new chain and tensioner will be required
parts are about £145 and its a 4 hour job
I think you mean the engine oil filler cap?
a top end rattle can be the timing chain, or sticking hydraulic tappets or even a pulley that's breaking up
but as its louder when you remove the filler cap this points to inside the engine and tappets tend to make a rhythmic 'tapping' noise not a 'clatter' and these engines are prone to timing chain wear its really all pointing to that
as to why smoking gets less over time perhaps you have had a leaking injector that was dribbling fuel - this can make for a smokey start and with miles and a good quality fuel they can sometimes improve?