S50B32 timing problem.

[MParallel]

I will update this thread with pics and more explanation, but in the meantime let me ask a daft question: can the S50B32 skip a tooth on the camshaft sprocket?

There is a long story behind this, but the short for now is that when at TDC and the cylinder one camlobes point 45 degrees upwards and inwards as per the Beisan procedure, the exhaust pistons doesn't reach the splined shaft (for the record, the cans gearboxes haven't been touched and Vanos removal was with disconnecting the pistons) I did this years ago when overhauling the Vanos with the Beisan kit, but it never run smooth on idle and doesn't pass the DIS Vanos test, on the exhaust side, which is the problematic side, intake is good).

I recently learned that it matters where the splined shaft is inserted, as not every spline is the same and makes a big difference in travel. But once more, I didn't touch that, splined shafts are in the gearbox.
Turning the cam within the physical end limits of the Vanos gearbox shows the splined shaft travelling a considerable distance.
It's just the position of the lobes that don't match.

Does anyone even know how far the splined shaft comes out of the hub when at its Vanos limit? Flush with the hub, a little out?

Basically when the splined shaft is at its end coming towards you so Vanos exhaust piston can be screwed on, the lobe is pointing upwards.

So with everything ruled out, I can't but help them thinking, the chain has skipped a tooth.

I haven't done such big engine jobs so it's all a bit stressful to me with my ocd and all, so any help/pointers is highly appreciated.

 

[Uncle Benz]

Without the timing tools you are just guessing. You need the bridge tool to both check and set the timing. It isn’t as simple as a spline tooth or a jumped tooth out. Fwiw I’ve never seen a jumped tooth, but I have seen plenty of mistimed engines.

 

[GolfDuck]

I think @Iain might be your man

 

[GolfDuck]

Or @Uncle Benz

 

[MParallel]

Uncle Benz: I didn't mention, but I do have the timing tools.
What I'm saying is that it's so far off, you can even see by eye. A 45 degree or 90 degree straight up pointing lobe doesn't need a timing tool to tell it's off.

With lobes at 45 the pinholes are pointing straight up. With the lobe pointing up, the hole is so offset you can't even fit the bridge.

Just for clarity: when I bought the car (45k miles) it ran beautifully. Then one day the Vanos oilpump bearing disintegrated. Still stunned ad to why. I could find two similar happening on the M5board with 2x E39 M5 vanos exploding bearings. Proper mess on such a low milage engine.
If a teeth skip happened, it was that moment of Vanos disintegration.
I took it off, rebuild a spare unit with Beisan kit and refitted. Splined shafts never left the cams, so technically, I didn't alter the timing in any way. Refitted Vanos was only possible by turning the cam away from its timed position, as splined shaft was too far in.

Hence why I can only think of a skipped teeth. Just trying to make sense of it all.

 

[Uncle Benz]

You need to retime the engine from first principles then I’d say. You have the tools, so it’s a piece of cake.

 

[MParallel]

Well I'm no expert here, so even with the tools, doesn't mean it's easy. You have much more experience.
They also won't get me far as they can't even fit to measure.
Unless of course everything gets undone. Chain tensioner, Vanos hubs, etc. That could be a step to far without assistance.

What do you mean by first principles?

 

[Uncle Benz]

Well I'm no expert here, so even with the tools, doesn't mean it's easy. You have much more experience.
They also won't get me far as they can't even fit to measure.
Unless of course everything gets undone. Chain tensioner, Vanos hubs, etc. That could be a step to far without assistance.

What do you mean by first principles?

First principles, you’ve covered it there. Everything undone.

 

[MParallel]

Ok clear.

Just a thought here, how likely is it the position of the hubs have changed within their slots? After previously studying pics and the Beisan procedure, it seems that after (re)inserting the splined shafts into the hubs, all that is holding them in position is the clamping force of 6 5mm allen bolts and the diaphram spring. Now I am no engineer whatsoever, but that seems so little for these forces needed to rotate the cams.

When my vanos went boom, possibly the shock made the hubs overcome this force and rotated a little. If it's not a skipped tooth (if possible) this seems the only other logical explanation on paper.

Because whatever happened, the range of motion of the exhaust cam with the crank locked at TDC is the wrong range within its turning circle. I'll upload pics later for clarity.

 

[Uncle Benz]

The spline can’t slip. It’s theoretically possible for the six clamping bolts to move if something major locked up. It’s essentially just like any other vernier adjustment pulley. That the only thing that could possibly move. For it to have shifted on the splines would need them to strip. That’s catastrophic failure. To jump a tooth on the chain would be similarly destructive. There’s not enough give in the system. It would have bent valves almost certainly.

 

[Uncle Benz]

The six clamping bolts do fit into six slotted holes. If theoretically something had locked hard and it had been pulled round it would be restricted by the end of those slots. That’ll save the valves from contact probably. You’ll see if that’s what’s happened when you undo it all. Thinking about what you are describing this is starting to seem likely

 

[Iain]

agreed with all of the above, for it to be a tooth out the chain has to be slack and the skockets loose, its really tricky to even walk the chain over the sprockets.

The vanos unit does have to be refitted at the correct depth which may be incorrect but i cant see that it would throw off the position.

With the timing kit its just time and trial and error really, TIS covers the timing process just have to work carefully and take your time and let the timing marks and kit guide you.

 

[MParallel]

The spline can’t slip. It’s theoretically possible for the six clamping bolts to move if something major locked up. It’s essentially just like any other vernier adjustment pulley. That the only thing that could possibly move. For it to have shifted on the splines would need them to strip. That’s catastrophic failure. To jump a tooth on the chain would be similarly destructive. There’s not enough give in the system. It would have bent valves almost certainly.

Yeah I mean the hub rotating, within the limit of their slots. Not the splined shaft itself. For that hardened metal to get stripped would need something so big, a stripped hub would be the last of the problem.

I'll try to see if I can see if if the allen bolts have moved relative to the slots. Maybe even moved to the very end of the slots.

The engine itself runs fine, it's just that at idle it rocks a little, which makes sense with the current situation the exhaust cam can't move to its ideal idle position.
You can also hear that when coming to a stop and the engine returning to idle, you can hear a metal 'clanking' as the vanos tries to move the cam, but can't.
When I pulled the vanos yesterday I also found the souce of this clanking, as the vanos oil pump driver has made quite a mark on the pump disc. I might even need to replace this as this gives unnecessary play.

In the Beisan instructions, they set the crank at TDC, then say fully retard both cams. In their pictures, the exhaust cam's groove then sits like this:

So this is the fysical end limit (fully retared) with crank at TDC.

Now on mine, the hole groove of the cam goes completely past the groove in the bearing cap.


Question, just to keep my sanity:

These slots, when the 6 bolts that hold the hub are tightened, do or don't the bolts stay fixed within the slot? (because I though that was setting the timing). But if so, how can the hubs rotate relative to the cam? Or are these slots the physical endpoints of cam rotation? When I move the cams with crank at TDC with the 24mm wrench, how can the hub rotate if the bolts don't move. Then what limits their travel? I thought I understood, but the more I think about it, the less I understand.

 

[Covkiller]

@Ollie you think you know it all with your self assured smart comments so fix this one then clever DIck.

 

[Uncle Benz]

The bit you aren’t getting your head around is the inner piece bolted to the cam with six capheads is not attached to the outer ring with the six slots. Maybe you should be getting someone to do this for you

 

[MParallel]

The bit you aren’t getting your head around is the inner piece bolted to the cam with six capheads is not attached to the outer ring with the six slots. Maybe you should be getting someone to do this for you

Ah yes that was it. I never has separate vanos hub parts in hand so it's all by pics and diagrams.

Oh yes, I will not tackle this alone anymore. A mate of mine has an M3 Evo as well and he's done this many times. At least this means the 'hub setscrews may have slid within the sprocket slots' is still plausible (and really the only option other than a skipped tooth, which is all but likely)

 

[Uncle Benz]

I’ve seen some horrors in my time. I’ve even seen one where the capheads on the back of the exhaust cam were blocked behind the sensor ring, preventing an allen key from being inserted. Instead of deciding they must have done something wrong and starting again, they had tightened the bolts with a chisel. Unbelievable butchery.

 

[MParallel]

If this BMW diagram is anything to go by, it shows all cylinder 1 lobes pointing up and inwards at 45 degreed and is this position both splined shafts sit flush with the front of the hubs.
When mine exhaust cam is in this position, the splined shaft sits well inside the hub.

 

[Uncle Benz]

I’ve seen some horrors in my time. I’ve even seen one where the capheads on the back of the exhaust cam were blocked behind the sensor ring, preventing an allen key from being inserted. Instead of deciding they must have done something wrong and starting again, they had tightened the bolts with a chisel. Unbelievable butchery.

Think actually this car might have belonged to @JamesNL . Iirc it came to me after someone had possibly replaced the head gasket, and it was running poorly. E36 Evo. He’ll correct me if I’m wrong.

 

[JamesNL]

Quite possibly sir. That car needed an exorcism.