Need some help/advice timing my S54 rebuild

[nextelbuddy]

i am rebuilding an S54 for another project. here is the current state of what I have done.

- short block with head removed, received new headgasket and head bolts
- placed crank at TDC with cylinders 1 and 6 all the way up while dampener is at TDC and locked and cylinders 2-5 are down (took pic to verify)
- backed crank about 30ish degrees for TDCC to place all pistons down in the cylinders
- installed headgasket and cylinder head and torqued to spec
- installed intake and exhaust camshafts. and made sure that i verified exhaust has reluctor wheel with 7 teeth and the gap and intake had 6.
- was able to rotate each camshaft individually with no interference if valves hitting any pistons since they were all down
- used timing bridge to place both cams at TDC with cylinders 1 lobes pointed at each other 45 degrees and both pins are in simultaneously with no resistance
- rotated crank clockwise back 30ish degrees back to TDC with the timing cover pointer pointing to the I in OIT and the crank pin is installed so everything cam and crank wise is in time.
- verified with a boroscope that cylinders 1 and 6 are both all the way up at top of the stroke and cylinders 2-5 are down
- installed exhaust and intake hubs using the Beisan guide and all bolts are threaded in by hand only
- rotated both rubs clockwise al the way until they stop
- tightened the timing chain tensioner to spec and tightened the chain guide bolt to spec
- installed the vanos unit with the splines installed made sure both splines are pushed in all the way into the vanos unit
- i have my splines marked so that when they enter the hubs they have instant rotation/engagement
- installed the vanos unit following beisan guide where vanos unit stops right at the dowel pins
- tightened the left and right hub bolts with a 10mm until the are snug
- backed off all 4 of the left and right hub bolts i just tightened by 1/4 turn
- tightened the 2 vanos mounting bolts which pulled the vanos until all the way tight to the cylinder head
- checked my intake/exhaust cam timing with the bridge and they didnt move, both pins still went in freely with no resistance
- installed the 3 bottom vanos unit bolts to spec
- used a 10mm to tighten the top 4 hub bolts that are exposed per beisan guide
- removed the bridge tool and the crank lock pin
- started to rotate the crank clockwise to get the top hubs to rotate so i could get to the bottom hub bolts



at this point this is where i got stuck. the crank stopped (ii was super slow and gentle) something was hitting. i used my boroscope and verified that the exhaust valves on cylinder 2 were touching and sitting in the relief cut outs on top of piston 2 so this is why it stopped.


i backed the crank off and rotated back to TDC on the crank and the cams and used my 24mm to wiggle cams back to TDC for the bridge tool

completely removed the vanos unit with splines leaving the hubs in place



i have no idea what is wrong now. never had this happen before and it doesnt make sense.

I would like to try rotating the complete rotating assembly with OUT the vanos unit installed. can anyone verify if that is ok to attempt? in a perfect scenario with NO vanos installed and the cams and crank at TDC with the bridge and lock tools, is it safe to rotate the crank clockwise to see if it goes all the way through? im curious in a good untouched engine, if you remove the vanos unit, is it safe to rotate everything with NO vanos installed?


here are some pictures i took in order from block at TDC then block at TDCC with pistons down etc...

image 1 - engine showing TDC with cylinders 1 and 6 up and 2-5 down
image 2 - crank at TDC
image 3 - crank at TDC different angle
image 4 - engine at TDCC backed out counter clockwise about 30ish degrees
image 5 - cylinder head installed and torqued
image 6 - intake and exhaust camshafts installed and torqued
image 7 - intake and exhaust camshafts installed and torqued different angle
image 8 - both cams timed at TDC with bridge and pins in place no cam gears installed yet
image 9 - cams at TDC with cam gears and hubs in place hand tightened and hubs rotated clockwise at max rotation
image 10 - engine placed at 30 degree tilt to show exhaust hub fingers horizontalish with ground as if it was in the cas
image 11 - screw driver at cylinder 1 before placing in spark plug hole
image 12 - screw driver on cylinder 1 showing piston is at TDC
image 13 - screw driver on cylinder 6 showing piston at TDC exactly like cylinder 1
image 14 - view showing cylinder 1 cam lobes pointed at each other 45 degrees and bridge/pins in place
image 15 - crank rotated back clockwise 30 degrees back to TDC and locked with pin
image 16 - showing intake and exhaust reluctor wheels are in appropriate places indicating intake and exhaust cam shafts are installed properly
image 17 - another view of cylinder 1 cam lobes pointed to each other while locked in time with bridge
image 18 - while cams are locked, shows cylinder 2 exhaust valves are open (not sure if this is good or not so verification would be helpful)
image 19 - image shows exhaust valves touching piston 2 after rotating crank an cams FROM TDC on my way to 180 degrees out but stopped halfway between TDC and 180 out

[enjoy_m3]

Quick question, the head looks clean so I'm assuming it was refreshed/rebuilt. Were the valves cut and put back in the same order? I believe the valve clearances would have changed. The machine shop that rebuilt my head put everything back in the same order/place. I also saved my shims in the same order so when I put everything back, I can reduce chances running into an issue. The machine shop mentioned to me that they did this so that my clearances wouldn't change as much. I'm not 100% sure if this caused your issue but it may be worth looking into. You should be able to rotate the engine without the vanos unit since using the cam timing bridge should set the timing. I remember rotating my engine after I installed the camshafts without the vanos unit to double check my valve clearances. Also, If I remember correctly, I just left the block at TDC with the locking pin at the crank when I installed the camshafts, I didn't back it out.

[nextelbuddy]

Quick question, the head looks clean so I'm assuming it was refreshed/rebuilt. Were the valves cut and put back in the same order? I believe the valve clearances would have changed. The machine shop that rebuilt my head put everything back in the same order/place. I also saved my shims in the same order so when I put everything back, I can reduce chances running into an issue. The machine shop mentioned to me that they did this so that my clearances wouldn't change as much. I'm not 100% sure if this caused your issue but it may be worth looking into. You should be able to rotate the engine without the vanos unit since using the cam timing bridge should set the timing. I remember rotating my engine after I installed the camshafts without the vanos unit to double check my valve clearances. Also, If I remember correctly, I just left the block at TDC with the locking pin at the crank when I installed the camshafts, I didn't back it out.

The head was just resurfaced just to get it cleaned up and it was cleaned at the machine shop but none of the valves were removed.

the only thing I did was I changed all the valve stem seals but I did not remove the valves.

All the valves and valve springs stayed with their respective position.

The same goes for the shims. I made sure that I put the shims back in the order that they were removed. I placed them on tape so that I would remember.

Even if it was shims, does it have to be some massive thick shims to cause that to happen lol

[Slideways]

How much was the cylinder head machined? If the engine had the head off in the past, then too much material could have been removed.

George Hill might have a better idea of what is happening here.

[sapote]

" im curious in a good untouched engine, if you remove the vanos unit, is it safe to rotate everything with NO vanos installed?"
No, as the pistons and valves are not in sync.

[sapote]

" rotated both rubs clockwise al the way until they stop
- tightened the timing chain tensioner to spec and tightened the chain guide bolt to spec
- installed the vanos unit with the splines installed made sure both splines are pushed in all the way into the vanos unit
- i have my splines marked so that when they enter the hubs they have instant rotation/engagement"

This seems fishy. How do you insert the splined shafts into the hubs without mentioning to turn the hub slightly CCW not more than 1 tooth?

If Forum EX valves hit the piston then it means EX cam timing is too retarded.

[Slideways]

" im curious in a good untouched engine, if you remove the vanos unit, is it safe to rotate everything with NO vanos installed?"
No, as the pistons and valves are not in sync.

Why? As long as the hubs and splined shafts are installed and the engine is timed, the valves should not contact the pistons. The VANOS unit not being installed won't mess with the timing. Now without the hubs and splined shafts installed, then the cams will not turn with the bottom half of the engine.

[sapote]

" tightened the 2 vanos mounting bolts which pulled the vanos until all the way tight to the cylinder head"
During this, did you see the hubs turning CCW? If not then the hub pretension step is too late. Try to set the hub pretension when the vanos is further forward.

[sapote]

Why? As long as the hubs are installed and the engine is timed, the valves should not contact the pistons. Now without the hubs, then the cams will not turn with the bottom half of the engine.

Without the VANOS, the splined shafts (assuming they are installed) will move forward (out of timing) as the sprockets try to turn the cam; if no splined shafts installed then cams are not turning with the crank.

[Slideways]

Without the VANOS, the splined shafts (assuming they are installed) will move forward (out of timing) as the sprockets try to turn the cam; if no splined shafts installed then cams are not turning with the crank.

I thought the VANOS was the only thing that could move the splined shaft in and out as it requires a lot of pressure to push/pull the splined shafts. I guess it could happen if there is no stop point at the end of the splined shaft.

[sapote]

"I would like to try rotating the complete rotating assembly with OUT the vanos unit installed. can anyone verify if that is ok to attempt? in a perfect scenario with NO vanos installed and the cams and crank at TDC with the bridge and lock tools, is it safe to rotate the crank clockwise to see if it goes all the way through? im curious in a good untouched engine, if you remove the vanos unit, is it safe to rotate everything with NO vanos installed?"

What do you gain with the vanos removed? With vanos install, it doesn't affect the cams timing as both vanos pistons are hitting the caps and move nowhere during turning crank CW.

[sapote]

I thought the VANOS was the only thing that could move the splined shaft in and out as it requires a lot of pressure to push/pull the splined shafts. I guess it could happen if there is no stop point at the end of the splined shaft.

The hub splines are helical, so rotation motion will cause the splined shafts to move forward; the reverse is true when the shafts moving linear to cause the hub rotating.

[eacmen]

Strange one. Maybe the valves were shimmed tight before the head was decked? How much did they take off?

[eacmen]

Also, are you using the original rods or aftermarket?

[nextelbuddy]

" rotated both rubs clockwise al the way until they stop
- tightened the timing chain tensioner to spec and tightened the chain guide bolt to spec
- installed the vanos unit with the splines installed made sure both splines are pushed in all the way into the vanos unit
- i have my splines marked so that when they enter the hubs they have instant rotation/engagement"

This seems fishy. How do you insert the splined shafts into the hubs without mentioning to turn the hub slightly CCW not more than 1 tooth?

If Forum EX valves hit the piston then it means EX cam timing is too retarded.

I think you hit the nail on the head. My exhaust cam was too retarded.

Once I took everything back apart and reassembled again I was able to get full rotation without any interference

The next issue that I hit was when I followed the beisan instructions for tightening the top three hub bolts, then removing all of the timing bridge locking components and rotating 180 to get to the bottom bolts. Every time I came back around my top bridge pins were no longer in time

Looked at the NAM3 forms Vanos thread and the guy that wrote that said that instead of just tightening the top three bolts, he went ahead and took the whole Vanos unit off. So I did that by disconnecting the splines since they were already held in place secured by the top three bolts. Then I torqued all of the hub bolts 12 ft. Lb then I reinstalled the Vanos unit at the helical gear reverse thread bolts and pushed the Vanos unit back on and tightened it up

Then I did a full rotation, checked my timing and it was in time

Then I rotated 20 more times and checked and my timing pins in the bridge fell into place just like the first time

So I think I'm good to go. I just needed to work through my steps. Methodically


I'm able to rotate all the way through with no interference and my timing pins drop in perfectly every time now.

Thanks everybody, I appreciate the help.