V.V.T. hub and cam sprocket alignment

crankcase · Post by **crankcase** » 11 Oct 2016, 07:30

Hi Everyone.

My daughter has a secondhand 2003 S60. It broke down, and after doing some checking,
the 3 bolts that hold the VVT hub onto the cam sprocket have, for some unknown reason, all come loose.
I tried putting in new bolts and tried to align the hub with the scuff marks made by the old bolts. The
VVT cam on this car is the one towards the front of the car. Using the scuff marks for alignment is the
only method I have tried so far to set the timing. Today I will check the actual timing marks, however,
since it appears likely the cam sprocket may be able to spin if not bolted to the hub, checking the timing
appears to be more complicated as a result. My question is how do I align the hub with the sprocket if the
bolts that hold them together came loose while the motor was running?

It seems the engine is an interference type and there may be further damage. So, I would like to try and
realign the VVT hub with the sprocket, reset the timing, and do check to see if it runs before replacing parts.
I don't hear any tapping or clattering when trying to start, just symptoms of being out of time. There is some
backfiring and poor sounding compression. The timing belt is still good.

Is this a good test for my situation to try and determine if there is further damage?

There is a nice YouTube titled "CVVT Removal and Setup", but it does not cover the case of aligning the hub
and the sprocket. They are already bolted together in the motor they show. So far I have not found any
reference to aligning the hub and sprocket so I hope some one here can help. Thanks.

Post by **F250** » 11 Oct 2016, 12:19

How far off was the gear ring from the scuffed bolt marks when you found it?

In theory, the VVT hub needs to be fully forward in it's rotation range when the timing is set (clockwise when looking at the timing belt from the passenger side of the car). You would simply follow the alignment approach outlined in the PDF document I posted a while back, but you only have one VVT hub to fool with in the process.

Post by **chrism** » 11 Oct 2016, 16:06

The problem, at least the way I read, is that all three bolts fell out, so there's no way of knowing if the gear spun just tiny bit, or maybe 120 degrees, or maybe 240 degrees.....

I'm seeing a need to start from scratch and put an alignment tool on the back ends of the cams. Then go through the whole sprocket alignment / VVT hub rotation exercise. Or maybe I'm misunderstanding????

Post by **F250** » 11 Oct 2016, 19:41

Assuming that the belt did not jump off, the hub could have only spun at most by about 10 degrees which is the amount of max rotation with the hold down bolts in place. To my mind, in reading what cranky wrote, it sounds like the bolts were simply loose, and not missing. Again, I'm still assuming that the belt was still on the gears. Regardless, I believe it would be best to do a "from scratch" alignment effort anyway just to make sure. You can use the the rear cam shaft marks to know how the cams should be oriented, once you've got the crank aligned. But I know that cranky already is well aware of that detail from what he's been going through on his other car.

crankcase · Post by **crankcase** » 11 Oct 2016, 23:30

Thanks for the replies folks. I apologize for the confusion in my initial post. All three bolts were completely off,
accompanied by plenty of ground up metal!

When I examined the sprocket assembly, I would say it had spun about an extra half inch beyond the travel
allowed when the bolts are in place.

Chrism, I too thought the sprocket could have spun by an unknown amount. I'm anxious to see what F250 thinks
now that I clarified the fact that the bolts were completely off. With the bolts gone, the sprocket could actually
be wobbled by hand with the hub remaining stationary (yikes).

F250, I have not found the PDF you mentioned yet. Could you post a link? I am reading anything I can find on the
subject and it's starting to make better sense. I still need to fabricate or buy the rear cam lock tool.

I think I have a pretty good understanding of what I need to do to set the timing from scratch this VVT motor, but
I'm still confused about a possible need to align the VVT hub with its' sprocket before I ever get started. It seemed
like this initial alignment would need to be done, so I really appreciate you all contributing your time to try and help
me get it straightened out.

Post by **F250** » 12 Oct 2016, 07:18

Oh... I thought you had run across it early in your other thread. Here's the link>>> Cvvt hub change on p2 volvos

Regarding the missing bolt conundrum, I am still inclined to think that even with the bolts gone, your intact belt and fixed exhaust hub position (it NOT being a VVT) would pose a limiting effect on just how much it could actually move. At the same time, there may be some valve damage if the "floating" gear ring moved excessively on that intake hub.

crankcase · Post by **crankcase** » 12 Oct 2016, 09:17

F250 you make a good point about the non VVT cam (and crank sprocket), and T belt
possibly limiting movement of the spun cam. On close examination of the VVT cam
assembly, it looks like there are "rivets" in between the bolt holes of the missing bolts.

One of these "rivets" (they are on hub) shows evidence of impact, most probably with
the loose cam sprocket. This rivit has some mushrooming on the edge where the impact
occured. But, the mushroomed area does not show evidence the sprockt had been sliding
over the mushroomed area. Hopefully this "rivit" also limited the sprocket from slidding much.

As you said, there could be valve damage. If I got it put back together, timed, and started,
do you think listening to the sound of the motor would reveal valve damage?

Post by **chrism** » 12 Oct 2016, 10:11

Crankcase,

If you get everything lined back up and timed properly, a compression test across all five cylinders "should" be a fairly good indicator as to whether you have any valve damage. BTW, here's the pdf file that F250 was referring to:

https://www.matthewsvolvosite.com/forums ... p?id=31807

It must be a fairly large file as it took a while to open, at least on my computer.

F250,

I think you are confused by all the "Cranky" people on the forum - this one is Crankcase - the one the other day is Crankycar. I guess you could say this is just a cranky forum.

Post by **F250** » 12 Oct 2016, 12:02

HAH!!! You are absolutely correct, chrism. I had not caught the nuanced difference in the names!

My apologies, Crankcase!!

crankcase · Post by **crankcase** » 12 Oct 2016, 12:59

Chrism, good point on the compression test. Please allow me to rehash the previous discussion and
hopefully also a clarify it as well.

I put everything back to gather as best I could since I could see where the bolts once were. I tried to
start it, but it would not run. I got some out of time symptoms: Backfire, poor sounding compression.

I think when the motor died due to the bolts coming off the hub, the sprocket continued to rotate
since it was still on the T-belt. The hub/cam, no longer bolted to the sprocket, tended to stop rotating.
However, as mentioned earlier, it looked like one of the rivets on the hub caught against the sprocket
so it limited the sprocket from continuing to spin unopposed.

If my reasoning is correct for my situation, attaching the sprocket to the hub using only the old bolt
marks to align the two probably resulted in the timing mark no longer being true. The timing mark is
probably now actually off by a couple of teeth when "aligned".

I may need to move the sprocket so the the timing mark is now off a couple of teeth, or try to realign
the hub and sprocket somehow, and then properly set the timing, or, some such equivalent action.

It seems like a big concern if the timing mark does not reflect its intended position. A "from scratch"
alignment would be compromised. One would think the two pieces in question should be keyed?