CVVT hub diagnosis

Canadian Moose · Post by **Canadian Moose** » 12 Sep 2016, 07:11

I am replacing the cam seals on a 2.5T with dual CVVT hubs. When I pulled the belt off I noticed that I can move the cam gears in and out on the camshafts. Is this normal or should there be no play? Do these things wear out?

If the play is normal, what is the diameter of the o-rings for the hubs? I'd like to replace those as well.

Post by **F250** » 12 Sep 2016, 07:25

They do wear out. I went through this on my daughter's S60 when it hit 166K miles and the PCV system plugged and pushed oil everywhere. The questions I have are:

1. How many miles do you have on the engine?
2. Have you experienced any episodes of severe oil loss (particularly if it was to the point of having the engine go into limp mode due to low oil pressure)?

I found that even the brand new hubs had about 1.0-1.5 mm of axial movement (in and out on the cam shaft), but no radial movement (up and down on the cam shaft). [I used my micrometer and a straight rule to determine the amount of play.] This was not far from the amount of movement in my "worn" hubs, but there was a significant difference in feel. With the hubs off the shaft, I would insert a finger and spin the hubs on the inner bushing. The "worn" hubs had a slightly gritty feel in the rotation, but the new ones were butter smooth. Also, once I had the new hubs installed, every time I would shift the hubs CCW (top of hub rotating to the left when facing the engine from the passenger fender), the new hubs would not leak nearly as much oil as the original hubs.

Canadian Moose · Post by **Canadian Moose** » 12 Sep 2016, 07:40

I am actually in the process of swapping an engine and this is a donor engine that I am working on. It has about 140k on it. The engine did leak oil through the front crank and rear main seals. The cam seals actually looked dry and there wasn't any oil pooled up on the cam cover.

There is no radial movement but there is definitely axial movement. VIDA has no information on diagnosis of the hubs so I wasn't sure how much movement was considered excessive.

Post by **F250** » 12 Sep 2016, 08:02

I had up to 1.9mm axial movement on one of my original hubs, which is less than I've seen others report. I believe the inner sealing surfaces must have been compromise din mine, though, because it did get into a low oil condition and thus the gritty rotational feel to them. That's why I changed them.

Would they have leaked once I did the rest of the timing belt, cam seal, and PCV system replacements? Not sure. I did not want to risk it, though, given that my daughter drives all over the state with her car, and there are plenty of "bo-dunk nowhere" locations where I would NOT want her stranded. She agreed, and she bought the the new parts (ouch!) for me to put in as an insurance measure.

If you search this site (and swedespeed) for CVVT or VVT hub threads, you'll find several which discuss others' experiences, and you'll also find my own contribution in terms of resetting the timing arrangement once the hubs are removed and replaced. >>> https://www.matthewsvolvosite.com/forums ... =9&t=77183

Canadian Moose · Post by **Canadian Moose** » 12 Sep 2016, 09:18

Alright, thanks for the info, I'll take a look. The pulleys on my old engine definitely have less play so I might just swap those out. Any idea on the size of the o-rings? The rings on the front caps appears to be ok but the back ones that ride against the cams I'd like to replace.

Post by **F250** » 12 Sep 2016, 11:27

I'm not completely sure which o-rings you're talking about on the "back ones that ride against the cam". The only ones I can remember coming across were the cap o-rings which screw into the face of each CVVT hub.

Canadian Moose · Post by **Canadian Moose** » 12 Sep 2016, 11:48

This post talks about the o-ring on the inner part of the VVT hub that rides against the cam.
http://volvoforums.com/forum/volvo-xc90 ... ded-81251/

Post by **F250** » 12 Sep 2016, 12:22

That is something I never dealt with at all. The hubs for my daughter's '07 must be different from what you're working with because they don't even look like those in the picture you posted. The ones on my daughter's car look like the ones pictured below.

: Dual CVVT Hubs.jpg (90.18 KiB) Viewed 7787 times

Canadian Moose · Post by **Canadian Moose** » 12 Sep 2016, 19:41

Yea, those are the same ones. The picture above is just what they look like on the inside when removed.

Anyway, I decided to just yank the cam covers off the 2 motors and swap the non VVT intake cam from the old motor onto the new motor. My old motor didn't have VVT on the intake cam. Will be less headache in the long run and I won't have to deal with that pulley wearing out again.

Post by **F250** » 15 Sep 2016, 07:50

I simply do not recall having done anything with the o-ring. Can't remember AT ALL -- CRS Syndrome really starts kicking in more and more aggressively as you get older.