I have a 2015 Seat Toledo and my engine is a 1.2TSI CBZB.

I will be replacing the crankshaft sprocket when I replace the timing chain and oil pump chain. This is the double sprocket that drives both chains from the crankshaft. I have downloaded all of the relevant official procedures that I can find from the ERWIN system. I cannot see any mention of this sprocket, but I believe it is the correct thing to do to replace it at the same time; it also comes in the HEPU kit that I am buying, which indicates it should be part of the replacement. I haven't yet got the kit, as I want to add all relevant parts and tools to my order. Therefore without having the replacement sprocket in my hand, I can't see whether it has any kind of keyway to align it correctly to the crankshaft. I have watched the few videos that I can find where this part is replaced, but I can't see details of the alignment. I know it is an interference fit, and I understand how to pull it off and press the new one on, including warming up the new one to about 100 degrees to make it easier, but I am nervous about the alignment of it, and the fact that I don't have any info available in advance, as I won't want to mess this job up!

Any information, experience, or photos would be appreciated. Thank you!

Both crank and cam sprockets are free floating.

You fit the crankshaft sprocket 'wherever it lands', then the cam sprocket and chain are fitted loosely.

Locking tools fix the correlation between the shafts, then the cam sprocket screw is tightened to make the alignment permanent.

How many miles has it done?

2 hours ago, Breezy_Pete said:

Both crank and cam sprockets are free floating.

You fit the crankshaft sprocket 'wherever it lands', then the cam sprocket and chain are fitted loosely.

Locking tools fix the correlation between the shafts, then the cam sprocket screw is tightened to make the alignment permanent.

Thank you. It's interesting to me that they're free floating. I'm not a mechanical engineer, so I don't know enough to have a strong opinion, but I'm surprised that such a critical thing is done in this way - especially as I would think there is a lot of tension in the chain as it pulls the camshaft around against the force of the valve springs.

I note from the procedure that when it comes to doing the second stage of the camshaft sprocket tightening (the further 90 degrees after the initial 50Nm), it doesn't instruct to leave in the crankshaft locking bolt and the camshaft clamp. So the camshaft sprocket bolt is to be tightened up purely against the sprocket counterhold tool, and the camshaft clamp T10414 is not in any way intended to hold the camshaft against this tightening - is that correct? It doesn't even say to check the timing again after doing the second stage tightening - so I assume there is no way that the sprocket can slip round a bit during that 90 degree tightening? Again, I want to not mess this up.

2 hours ago, Breezy_Pete said:

How many miles has it done?

About 120,000. The reason I want to replace it (and thoroughly) is that it has been making the "normal" timing chain noise for years, but recently I think it has got worse - in particular, it isn't just noisy for 3 or 4 seconds after starting the engine, but seems to stay noisy until the first time I get the revs up. I'm hoping to not replace the car any time soon, so I believe I just have to do this before it's too late.

It is a little surprising, but just the way things are done in recent decades.

The interference fit of the crank sprocket is sufficiently tight that removing the old sprocket may be considerably more difficult than fitting the new one.

The tightening of the cam sprocket screw needs to be carefully done so that all the force of the tightening is against the counterholding of the pulley. Having the locking tools in place will not be a problem here, but the cam one particularly is an alignment guide, not a force resisting component.

I would imagine that at 120k there would be minimal wear on the crank sprocket, so it could be left original if you struggle.

I believe the majority of the wear in the system that is generally thought to be chain elongation is actually just wear of the plastic chain guides, which effectively shortens the path that the chain follows.

So make sure those are replaced.