V.V.T. hub and cam sprocket alignment

crankcase · Post by **crankcase** » 12 Oct 2016, 13:01

Thank you F250, but all is well.
No apology needed.

crankcase · Post by **crankcase** » 13 Oct 2016, 05:31

I'm getting a better understanding of how to align the hub and sprocket, and what considerations to keep in mind.
I think I need to start with finding top dead center on the intake cam. That condition in a single overhead cam system
can be determined by observing when all the valves are closed. The VVT does does not appear to affect the exhaust
valves on this engine, so the timing mark on the exhaust sprocket should still be good.

1.) How can I observe if the intake's lobes are pushing on the intake valves?
2.) Can this even be done, what do I need to remove to see?
3.) Is there a single lobe per valve, or multiple lobes per valve?
4.) Should I look for top dead center when the hub is at "rest", or in the "spring wound" state?

I apologize for asking a bunch of questions instead of doing a bunch of reading.
I've only got about two days to get this figured out and I barely understand what is happening.

Thanks again for any help.

Post by **F250** » 13 Oct 2016, 14:57

Carnkcase...

Don't apologize for trying to learn and understand. When I started out on this journey back in May with my daughter's '07 S60 2.5T, I was on what I now call a "vertical learning curve". The PDF I generated was what came out of having completed that journey in hopes that what I learned could be of help to someone else. I still think it has some info which can help your situation.

Questions 1-3... don't worry about these particular details. You shouldn't need them.

Question 4. If I recall correctly, the "spring wound" position (not "at rest") is when the hub is spun by hand 100% clockwise (towards the front of the car). That is the position it needs to be in when the belt is installed on it, and there should be no slack in the belt between the intake hub gear and the crank gear.

Read through the PDF linked earlier by chrism and you will find a picture of how the rear end (driver side) of the cam shafts should look with the rear cam covers and CPS tone rings removed. There are uniquely positioned notches machined into the rear of the cam shafts, and they get oriented a certain way for alignment. The document will also address how to identify the original timing marks on the exhaust cam gear and then you can see how to position the gear ring on the intake hub (after making sure that the hub is rotated fully clockwise).

crankcase · Post by **crankcase** » 13 Oct 2016, 16:44

F250, I confess I just got around to reading the PDF.
THAT is the missing piece to my puzzle.
I now have a path to follow.

crankcase · Post by **crankcase** » 13 Oct 2016, 17:01

Is there a simple way to verify timing that does not involve locking the cams and rotating the hub?

I guess there is no way to verify the cam is in the right position with out seeing the slots on the back of the shaft.
Given my sprocket and hub have come loose from each other, I suppose the answer is no.

Post by **F250** » 14 Oct 2016, 08:58

Use the timing marks on the crank and the hub gear for the exhaust cam. However, in your particular case, getting the intake gear set properly will require you to check the rear of the cam shaft machine marks under the rear cover. You don;t need a locking tool unless your hub has moved, but that becomes irrelevant if you get the rear cam marks lined up properly, and then just set the intake hub gear ring so that it's timing mark lines up with the corresponding notch in the top cover on the front of the engine.

Post by **chrism** » 14 Oct 2016, 12:51

F250,

I was skimming through your pdf instructions (good job by the way) and saw one place that you might want to revisit. You correctly say in there that when aligning the cams, via the slots on the back end, that the slots will be parallel but one slot will be above center and one below center. However, you say it doesn't matter whether the intake is up and exhaust down - or - intake is down and exhaust is up. The problem with that is you don't want the intake sprocket on its index mark when its slot is down, nor do you want the exhaust sprocket on its mark when its slot is up. This would be putting a cam 180 degrees out of sync - recipe for disaster. When both sprockets are on mark, the intake slot should only be above center and the exhaust below center.

Post by **F250** » 14 Oct 2016, 15:57

Excellent catch, chrism. I'll get that clarified and resubmitted right away.

Post by **F250** » 14 Oct 2016, 16:51

OK. The document is revised to address that issue you brought up, chrism. Thanks again for catching that.

Just as a reminder, the whole compilation effort was done with a short term and fairly limited level of experience with Volvos, so there may be another detail of two buried in the document which went over my head at the time. If you see anything like that, let me know and I'll revise the PDF and get Matt to report the corrected document into the forum's reference file list.

Here is the revised document.

CVVT Hub Setting Guide - Rev2.pdf: (763.03 KiB) Downloaded 249 times

crankcase · Post by **crankcase** » 14 Oct 2016, 21:37

Thanks everyone. I'm feeling comfortable with what is going on and what
needs to be done. Now that I've studied the PDF, I will check it out tomorrow.
The PDF is huge resource, and thank you so much for taking the time to do it!

My new cam shaft locking tool set is on the way and should be here in about
a week if I need it. I never pass up an excuse to get a new tool!

The threads where the bolts screw into are in sad shape. Do you think I could
use a little thread lock to test it, or possibly as a permanent fix?

My first time trying to re-bolt, I would estimate I put the new bolts on to about
10 ft-lbs. That's about what I felt comfortable with given the state of the threads.

Any chance someone could supply me with the rated torque for the 3 little bolts?
I have the yellow hub, but can get the numbers off the hub if needed.

V.V.T. hub and cam sprocket alignment

Re: V.V.T. hub and cam sprocket alignment