M156 change cams and lifters
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C63 s204
M156 change cams and lifters
Planning to replace cams and lifters on my c63 (m156). I’ve gathered most of what I need, but a few things are unclear. So any advice on this would be greatly appreciated
- I understand that exactly 40° TDC is important. But in order to get a detailed view of the marking on the engine block, the serpentine belt and support pulley need to be removed. But is this really necessary?
My plan was to inspect the mark using a borescope, set the crank slightly before 40°, and then slowly rotate it to 40° while attempting to insert the rear cam locking tool until it sits flush.
If it does not sit flush after clearly passing 40°, I assume I would need to rotate the crank another 360° because the cams would be on the wrong phase.
So basically my question is: isn’t the fact that the rear locking tool sits flush the most important factor- > if I can see through the borescope that the marks align and the rear locking tool sits flush, shouldn't that be sufficient? - I’ve read that sometimes the rear locking tool sits perfectly flush at 40° on one bank, but the other doesn’t. What is the correct procedure then?
- Since I have a FL, I assume I have the adjusters with the non-threaded locking hole for the adjuster locking tool. However, when the front locking bridge is installed, it seems impossible to fit both tools simultaneously.
I’ve seen YT videos claiming that as long as the adjuster gear remains engaged with the sprocket, timing and preload are effectively retained. Based on that, my understanding is that you could: install the front locking bridge and rear cam locking tool, loosen the center bolt without fully removing it (thereby keeping the adjuster engaged with the sprocket), remove the front locking bridge, install the adjuster locking tool, and then fully remove the center bolt and adjuster. The question is: is this correct or can something inside the adjuster still move although both gears are connected to the sprocket? If so I could just insert a pin with the same thickness of the tool into the hole since the gears are already locked via de sprocket - Is the front locking bridge required for removal, or mainly for installation/alignment of the trigger wheel?
- When tightening the center bolt with all locks in place, is there still a risk of the adjuster moving and affecting crank position?
- Can the adjuster be installed in any rotational position, or does the front locking bridge enforce a fixed orientation?
I know that if installed top down the locking hole would be at the wrong side etc, but does it matter if the the adjuster is installed like 10 degree more to the left or right than it initially was, will something prevent this from happening - What assembly lube/oil should be used for cams, journals, lifters, and adjusters?
- When removing cams, there is oil trapped inside. I can assume it can simply be poured back into the engine?
- I don't have an adjuster rattle (car has 70k miles) so the idea was to check if the cams are properly locked prior removal and visually inspect them.
But it turns out ok I would leave them be. I guess that doesn't hurt or is there a rule that they need to be done at the same time with cams/lifters?
Last edited by JohnMerc63; May 17, 2026 at 12:21 PM.
