This post is regarding cam timing and cam sprockets.
Sooner or later any DIY mechanic will need to change the timing belt and VVT sprocket/sprockets.
There are tons of how-to procedures out there explaining how to do this, and I've
also got the VADIS procedure, but non of these answers the million dollar question
most people encounter when they're unpacking the new VVT-sprocket and finds out
there's no keyway or markings to aid in how to put the new sprocket back on the camshaft.
This post is an attempt to settle this question once and for all, since there's no way
I'm going to pull parts and then not knowing exactly how to put them back on.

Let me start by explaining how I think it's done and then please comment to either confirm or correct what I'm saying.

My engine is the B4148S2, 1.8 litre, non turbo, non GDI with a VVT sprocket on the intake cam.
There are two kinds of sprockets in circulation: One with a helix-gear and return spring, and one with a locking pin and vanes. Mine is the version with the locking pin and vanes.

Let's say I've made it so far as to remove all parts needed to gain access to everything.
I've got the crank locking tool and the cam locking tool ready.
After inserting the crank locking tool into the hole behind the starter motor I know that the
crank is in the correct position, no doubt about it.
Now the cams should also be correctly aligned with the crank provided the previous owner or a workshop mechanic or timing belt slip/wear hasn't messed things up.
There is a procedure to check wether the cams are correctly aligned or not, let's say I've
followed this procedure and now it's time to insert the cam locking tool.
Now the crank/cam timing is correct no matter what previously made markings on the cam sprockets
may tell you. As stated before, you never know what people or wear/belt slip may have done to the alignment.

Now it's time to remove the timing belt and pull the VVT-sprocket.

Looking at the new VVT-sprocket there is no keyway, nor are there markings on it.
Not even a hint of a mark in the engine block either, just two small low accuracy notches on the plastic timing sprocket cover.
-Why?
Are the engineers at Volvo morons? There must be a logical reason for the total lack of alignement marks or keyways, and the reason is they're not needed.
They're not needed simply because the engineers at Volvo counts on the mechanic using the correct tools for the job;-the crank and cam locking tools.

You can put the VVT-sprocket(s) on as you wish, provided you torque it (them) down just so that they're able to rotate slightly as the timing belt is tensioned using the correct tensioning procedure.
After the timing belt is tensioned the VVT-sprocket is torqued down with the correct value.
The idea is that the timing belt must have the same tension all around, so that when you remove the cam locking tool after the sprocket(s) are torqued down there is no uneven tension on any section of the belt to cause the cam shafts to change alignement once the locking tool is removed.

As I said before, please confirm or correct my understanding of how this works.
I can see no other reason for why Volvo has no keyways or markings than that such markings are simply not needed.

 

I marked my new VVT gear by lining up the old gear with the new and placing my own mark to match the original factory mark.

Once the cam holder tool was in place I tightened the VVT gear to the cam so that it rotated into perfect position just as the desired torque value was set. It took a few tries. I've not had a single P0015 engine code either.

While I agree you can place the gears on as you wish, I ask why would you? Place them into position lined up with the marks on the plastic cover just in case you need to verify your timing in the future. This way you won't have to install the cam holder tool just to check if your belt has slipped. JMHO. Sounds like you have everything covered though.

 

Thank you for answering.
The last time I fiddled around with a Volvo was with a 1972 Volvo 142 with a B18A engine.
Needless to say the more modern stuff is unknown to me, so I like to research first and then pull parts later. Now I'm just waiting for summer so I can change timing belt, idle roller, tension wheel, water pump, VVT-sprocket and serpentine belt plus tensioner.
The engine uses very little oil, no oil leaks or coolant leaks and runs fine except for a no start condition a week ago. Cleaned the IACV, throttle and the MAF and it seems to run fine after that.

I'll follow your advice on lining up the old VVT with the new.

 

For me at least, I thought the exhaust cam had a preload on it. With the cam locking tool in place, the belt loosened, the cam had a minor prespring and wanted to rotate forward. I marked my new pulley the same as the old and upon placing the new one back on in the same position and tightening everything down, rotated it back into position when putting the belt on.

I'm not sure if I needed to do any of that preload, but I don't have error codes for timing. I imagine if I did it wrong I'd know about it.

 

Oh yes, I imagine you'd know about it. As I understand it modern engines are quite picky on correct valve timing.
Apart from the dreaded CEL in the instrument panel, one thing to look out for is a loss of power either in the low end or high end of the rpm-range. The VVT system ensures more or less equal power all across the rpm-range. As little as a one tooth error should be noticable.