2002 s60 Is this the right way to set timing for VVT motor?

turtlehead · Post by **turtlehead** » 27 Jun 2015, 19:13

Okay, I'm just trying to make sure I am doing this correctly. Rebuilt the head on my S60 which has VVT on the intake cam, so of course I am replacing the cam seals which means the VVT hub had to come off.

Now I've put everything back together, but the engine only runs for about 30 seconds before it sputters and dies, and another contributor here suggested that maybe I've set the timing wrong, because I get a crankshaft sensor intermittent code, and a camshaft position sensor error code as well. I have installed new crank and cam sensors, and I'm still getting the same codes. Its either the timing is off, or maybe the engine computer is not reading things correctly?

So here is how I am setting the timing. I have the crankshaft at the correct position, which I've confirmed by sticking a 3/8" extension through the little hole in the crankcase that lives behind the starter, and moving the crankshaft counterclockwise until it stops. I can also see that the timing marks on the gear match up with the casting marks on the crankcase.

I have the camshaft position tool locking the cams in the correct position, which when I look at the grooves in the rear of the cams (with the locking tool off, of course), the rear groove is just below the seam, the intake is just above. The locking tool only fits one way, but I'm double checking everything at this point.

I feel confident that I have the camshaft and crankshaft set in the correct relative positions.

The VVT intake cam is not spring loaded, so it is fairly easy to set up, or so I believe in my own mind, ha ha. Facing the engine crankshaft pulley, when the engine is running, everything turns clockwise, so if I adjust the VVT hub so that it reaches its clockwise limit, regardless of whether the cam gear marks are lined up with anything, the timing should be correct, shouldn't it? The way the VVT works, as I understand it, is the engine computer uses oil pressure when it senses the need to advance the timing, i.e. make the hub turn slightly less clockwise relative to the spinning intake cam. Just to be clear, I AM using the cam gear marks and lining them up as best as I can with the position marks on the can cover, but my question is how precise do I have to be in lining up those marks? If the timing belt goes on with the hub set at the clockwise limit it should be correct, or am I not right about that?

Somebody please straighten me out, or maybe confirm that I've got the timing set correctly using this procedure. I'm pulling out what hair I've got left, and if it isn't the timing that's causing the problem, then I need to start looking at something else.

Just in case it makes any difference, this is a naturally aspirated, non-turbo engine.

Post by **precopster** » 28 Jun 2015, 02:37

Try this:

turtlehead · Post by **turtlehead** » 28 Jun 2015, 03:59

Thanks, precopster! It is an excellent video, and after watching it, I believe that I am following the correct general procedure, at least it looks correct to me.

The mechanic in the video, however, makes two paint marks on the cam tower and back surface of the exhaust cam gear before removing the hub to help him align it on re-installation, which is something I alas did not do. So my question really has to do with the fine tuning aspects of hub installation, I guess.

Both the intake and exhaust gears have little bolts on the front face of the cam gears to allow for fine tuning. I've never used them, although I've read posts from fellows who advanced their timing by loosening the cam gears and adjusting their relative positions. I don't have any desire to do that, I'm just trying to make my engine run without throwing a code. I understand that the vvt hub needs to be able to self adjust itself (via oil pressure) while the engine is running, which is why we go through all the trouble of making sure the relative position of the cam gear to the vvt hub is correct. But is this where I am falling down on this job? The engine starts reliably, which indicates to me that the timing is correct at least for the purposes of starting. Is it throwing a code because I haven't aligned the hub correctly so the vvt can do what it is designed to do after the engine is running?

I'm going to dive back into it this morning, so any advice is welcome. As of now, I have installed the timing belt with the hub at its clockwise limit. I'm going to re-examine the vvt adjustment, so any advice here is welcome.

Thanks again, guys. If we learn by failing, it feels like I'm getting on my master's degree on this job.

Post by **precopster** » 28 Jun 2015, 15:27

If timing marks line up after CVVT hub removal and replacement you have probably done it correctly. I can't think of a resource for this procedure other than Vida.

If cams are removed you should be able to simply slip the larger seal on from the rear of the cam without messing with hub removal.

Post by **jimmy57** » 28 Jun 2015, 17:14

Just to be sure these points are clear: with crank in correct spot and cam tool locking cams the cam belt is installed with the cam gear bolts still loose from the intake cam CVVT hub and the exhaust cam and then tensioned by overtensioning belt and then bring it down to the right tension with indicator between the "goalposts" on the tensioner. Now you rotate the cvvt hub CW until it stops using the TX55 center cover plug. Make sure the intake CVVT has not run the bolts against the slots on gear, i.e., the hub actually has gone to hub motion limit and was not stopped by the gear bolt slot ends. If it has then the gear needs to be moved one belt tooth CW. Also make sure the exhaust cam gear has not run against the bolts by reaching the end of those slots. In that case that gear needs to be moved one tooth whichever way will allow it to "float" when belt is tensioned as opposed to running to end of slots on bolts. While all of this going on FORGET the marks on gears. Make new ones that are prominent with a triangle file. The marks were put on the gears after the aforementioned timing setup was done. The marks are often not really accurate. The marks are only there for use when timing belt is removed and refitted for a replacement or water pump change. Even then making your own crayon or paint marks is still a GREAT idea.

turtlehead · Post by **turtlehead** » 29 Jun 2015, 04:59

Thanks, Jimmy57. That is the clearest explanation of the issue I've ever seen. It sounds like I'm on the right track- the most important thing is to make sure the vvt hub is able to reach its clockwise limit with the timing belt installed, and to make sure the position of the hub relative to the camshaft is correct, which I can determine by making sure the hub reaches its limit without being impeded by the 8mm set screws on the gear. I should be able to check it without removing the timing belt.

I will let you know how things progress.

zooklm · Post by **zooklm** » 07 Aug 2015, 21:12

I saw this explanation and have a question. I replaced the belt by linine up the marks, loosing the tensioner, removed the old belt and tensioner and installed the new belt and tensioner without moving the marks. I rotated the engine by hand for 3-4 revoluteions and everything seemed fine. I did not loosen any of the camshaft gear bolts. I had read that the belt could be changed this way if you are careful. When i started it, it runs rough, like the timing is off. Do I need to try again to set the timing by loosen the gear bolts and starting fron the begining? By the way, the engine is a replacement for the original motor that had thrown a rod. I did the belt change while I had it on the engine stand prior to installing it. The engine is the 2.4 turbo in a 2002 V70XC wIth 96k miles, which is why I did the belt.
Thanks,
Lee

turtlehead · Post by **turtlehead** » 08 Aug 2015, 06:07

Sounds like you had the right idea. There are two things that absolutely must be correct- the position of the crankshaft, which you check by lining up the marks on the crank timing gear, and the position of the cams. Because the VVT hub allows the cam gears to turn on their own, the only way to be absolutely sure about the position of the camshaft is by looking at the opposite end. The camshaft slots must be parallel with the seam where the valve cover meets the cylinder head. I have the cam positioning tool, which costs about $100, I found it very helpful as I didn't have to worry about the cams shifting. You don't really need it for a T-belt change, if you are careful.

Once the cams and crank are in the correct position, you then have to deal with the VVT. Remember, everything turns clockwise, so when the timing belt is on, the VVT mechanism needs to be at the clockwise limit, i.e. turned as far as it can go clockwise. When the engine starts, there should be no CW slack in the timing belt; if the camshaft slipped during your installation, the mark might look to be in the right position, but the timing would still be off. The engine computer uses oil pressure to adjust the relative position of the VVT mechanism, but everything starts from the clockwise limit.

If you remember that, you should be fine. It isn't clear from your description whether you checked to make sure the VVT was at its clockwise limit when you put on the belt. Its possible that even though your marks were lined up correctly, the camshaft moved while you were installing the belt. You can double check your work if you line up the marks (turn the engine CW to do this), leave the timing belt in place, and then go look at the cam slots at the opposite end. If they aren't parallel with the seam, you gotta do it again. On my car there is a plug covering the exhaust cam that you have to destroy to get out but its only a $5 part, and there's no other way to be sure you did it right.

Otherwise, you can try re-installing the T-belt and just make certain the VVT hub is at its clockwise limit. Did you hear the engine run before you installed it, BTW?

3carmark · Post by **3carmark** » 08 Aug 2015, 15:42

what i have found helpful is tightening the vvt bolt (55 torx) slightly to make sure you have the slack out of the vvt unit just put enough tension on it to make it hard to turn and this keeps the vvt in the right posistion

zooklm · Post by **zooklm** » 08 Aug 2015, 21:00

I know that when I did the belt, i did not take off the end cap or cam positioner sensor cover, so I really don't know if the end of cam marks ligned up. Also, I did not turn the cvvt mechanism all the way CW. I did not turn it at all. Do I need to loosen it prior to turning it? I did unplug the cvvt and it seened to run/idle better, though.
looks like I need towork on it again. Since I am not fully changing the belt, do I need to take off the serpentine belt to get the timing belt cover off?
Thanks for the help.
Lee