[Blaikenstein]

I’ve had an ongoing issue with my vanos moving up/down on the exhaust side. I thought it was due to the threads being bad so I timeserts them all but I recently broke a 12.9 grade bolt in the top passenger side, that bolt has been the most problematic.

A few ideas off the top of my head are a bent camshaft (removed exhaust cam looking for a shim) or a bent exhaust sprocket.

Do either of these seem like the right track or does anyone have any experience/suggestions?

[M3_#67]

Are both dowels in place?

[Blaikenstein]

Just the exhaust side down is in there. The intake side isn’t but it’s not moving at all.

[M3_#67]

Do you happen to have access to a dial indicator? If so, you could check the circular run out on the sprocket hub of the camshaft by turning the engine over by hand. That should tell you if it's bent for sure. Especially if it's moving the vanos unit like that.

[Blaikenstein]

^good call on the dial gauge. I’m showing minimal movement on the cam so it’s good. The exhaust hub is oval and highest in the timing position.

Current theory is I tightened the top hub bolts to much causing it to have an oval movement.

[M3_#67]

Yeah perhaps by tightening the bolts lop sided and not in a crisscross/star pattern could maybe have the hub sitting crooked. This (the movement) start after removing the cam?

[Blaikenstein]

I can’t say for sure when it started. I’ve pulled the vanos and retimed it several times messing with one thing or another. I’m thinking I’ll install the splines into the hubs first this time and check for roundness with the dial gauge.

This isn’t that complex of a job but if there’s a booby trap I’m sure to find it.

[BubbaTree]

Have you run the vanos test? What were your results? I just installed a new upper chain guide and oil pressure regulator, and now have an error showing an exhaust leak. DIS points to a bad solenoid, but, I didn't have that issue before the work was done. Maybe I overtightened the hub bolts, too? I'm going to pull the valve body and clean it to see if that helps. Anyone have any other clues?

[Blaikenstein]

If your timing is off at all it’ll idle like crap. I sucked up some rtv into the valve body and it only allowed the vanos to retard the timing but not advance it back or vice versa. Cleaning the valve body is the easiest first step, ultrasonic is best if you have access to one.

If your hub was tightened lopsided your timing can be fine but you’ll see the vanos unit physically bouncing as it’s moving in an oval.

[mrgizmo04]

Originally Posted by Blaikenstein

I can’t say for sure when it started. I’ve pulled the vanos and retimed it several times messing with one thing or another. I’m thinking I’ll install the splines into the hubs first this time and check for roundness with the dial gauge.

This isn’t that complex of a job but if there’s a booby trap I’m sure to find it.

You have to tighten the hub bolts 3 at a time, but in several passes. First time, tight enough to provide enough tension on the diaphragm spring so timing doesnt move, then you tighten more with every rotation/pass, to avoid exactly this, a possibly uneven/"oval" preload.

Installing splines into hubs first is not "proper" way of doing it and can cause other issues, unless you just want to insert them and tighten all 6 bolts in criss-cross just to test if the uneven/oval issue is mitigated, but then reinstall them in the proper way (splines to valve body pistons first).

Where did rtv get sucked in from? There is a tiny amount of rtv needed in the 2 corners where the the valve cover gasket would mate with the edges where the cyl head/vanos gasket/vanos valve unit body meet. That is it. You put some rtv there after the vanos valve body is tightened down to the head and you are ready to put the vcg on. Rtv is not needed anywhere else.

Sent from my SM-G950U using Tapatalk