need cam aligning help

[mishar]

It seams to me that we are not talking about same tool and procedure.

[A8CT]

yes and yes...

The holes on the cam bar are indexed and only fit one way. Usually when you release tension and remove the belt, the cams don't stay perfectly aligned. I've done this 6 times now.

Using the cam bar, you need to move one or both cams to make the holes line up so the cam bar will fit.

Bob

[mishar]

I did this many times but never on A8. That's why I am asking. My next question is why do you remove tooth belt before you fix camshafts with the alignment tool?

[A8CT]

you don't...

The procedure calls for locking the cams, then removing the belt. You need to remove the cam bar in order to get the new belt on so it's on/off a couple of times.

It needs to be locked to unbolt(not remove) the cam spockets and locked again to torque. Cam sprockets HAVE to be loose enough to rotate on the camshafts when you set the tension on the belt.

[mishar]

As I understand what you are talking you are changing relative position of camshafts and sprockets. You said that driver side cams tend to move when released. So what would hold them in place if sprocket is loose while you tension the belt?

I don't see why can't you get the new belt on with tool in place. Can you explain?

[MP4.2+6.0]

That's the part of this thread I did't follow. Of course the cam locking tool has to be removed to get the belt off and on. Either that or you need to pull the engine and "slip it off the back" instead!

And as stated earlier, when the tool is removed, the cams often rotate on at least one side. And not documented, but I would say be really careful! A finger in the wrong place when those things rotate hard w/ valve spring pressure driving them could be at least a trip to the emergency room.

[A8CT]

ok, I think I found the missing piece

The camshaft lock bar is keyed (not talking about the holes but the center) so it fits onto the end of the camshaft. If you look at a pic of a camshaft you'll see it's got a flat side.

That's the part that locks the cams together. Onto that slides the cam sprocket and a plate which has the previously mentioned holes that the pins of the crank bar go into.

The net is the cams get locked together via the bar and it only fits on one way. But, the cam bolt which torques against the "plate" is loose enough so the cam sprockets can rotate freely around the locked camshafts.

[MP4.2+6.0]

Doesn't work out in the field/garage as you might be thinking conceptually. If belt ran directly from one head across to the other from the tops of the cam wheels, then maybe. But given the way it wraps, tool really needs to come off at the interim step. You could physically cut the old belt, but you are left w/ the same dilemma w/ the new one. And, where you free up the most slack is down at the crank, but it's very tight in there and you really need the belt otherwise free to move to get in into/out of there. Maybe not so obvious too is the belt is quite inflexible laterally across the teeth--hard to "deflect it" without twisting it some, but ability to twist it takes a fair amount of slack to start.

[MP4.2+6.0]

if you are fighting with one head or the other to get the cams back in position, I start by getting the side that is cooperating positioned exactly, using the bar loosely bolted to that side only for leverage and eyeballing it to the other side (bringing it in front of the cam centerline where things are more out of position). Then I carefully unbolt that side behaving better and not vibrate things so it might suddenly turn. Then I go to the problem side and bolt the bar only there, using it as a lever arm to then bring that side's cams into position with the side I already fine tuned. Now if it goes well, I can bolt to both sides. If not, repeat. Typically even with that valve spring pressure I can get it to rest in the right position as long as I don't get a cam started moving via vibration or inadvertently pulling the belt a bit.

[mishar]

Originally Posted by A8CT

ok, I think I found the missing piece

Yes you did. I didn't know that the tool can fix camshafts leaving sprockets loose. Now that part is clear. It is also clear why they did it this way, quite differently than many. Gain is that you can align camshafts more precisely not relying on timing belt precision (not that it is all that important ).

Now the second part of it. If you take the timing belt off the water pump and lift that side up you will have a lot of slack and it comes off without taking the tool off. No cutting. I am not sure if it would be possible to change the water pump with the tool in place. That's actually my question.