So I have bought a good Bentley service manual and watched a you tube video prepping for my timing belt and cam seal replacement. My question is why are the cam sprockets loosened but not removed with the cam holder installed? And then installed loosely and the tightened only after belt is on? Are the cam sprockets keyed to the cams? Is it possible to mis align the sprocket to the cam shaft?

 

The cam sprockets are not keyed to the cam. The camshaft is tapered as is the inside of each sprocket. When you have the cams locked with the tool and the crankshaft locked with the locking pin and the belt is on and tensioned then you tighten the nuts and drive the sprockets up the taper, the camshafts will then be perfectly timed. When you do the work it will become clear.

 

So there is no chance the cans will move after sprocket bolts are loosened and sprockets are removed?

 

Or are you saying the pieces the locking tools pins go into are keyed to the cam?

 

I don't think I said that. If you loosen the nuts and then knock the sprockets loose the cam WILL move. You must install the cam locking bar before you loosen the nuts.

 

The piece the locking bar attaches to is keyed to the cam.

 

Ohhhhhh ok now it makes sense. I thought the oval shaped pieces were part of the sprockets. So as long as those oval pieces are in locking bar, the actual cams are positioned properly. Thanks for clearing that up!