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I was re-watching the Legit SC video series on the m156 whipple mod build last night, noticed he does a VERY detailed rebuild discussion of the VVT gears. It’s always possible that tiny spring or plastic oil cap is missing or dislodged or something. Hell, he dropped his on the floor while filming…
Well I made some progress this weekend. Unfortunately not as much as I would’ve hoped thanks to a completely stripped screw connecting the bank 2 timing cover ground. And I spent maybe too much time trying to align the timing tool.
Some progress pics… Replaced coolant temp sensor first Coil packs removed Absolutely screwed screw. Although this was also after some failed attempts to extract. Location of botched screw Wiring harness pulled back and valve covers removed Bank 1 timing cover removed
For the stripped screw cap, I first tried a reverse thread screw extractor. That just rounded it off inside. I then tried to notch a slot with a dremel. Cap metal just broke away when torque was applied. I’m now trying out letting some Kroil penetrating oil sit overnight as well as a Torx T30 curing attached to the cap via JB weld after cleaning it off with acetone. Hopefully able to address that..
Anyways, powered on with bank 1 while I wait for that. No play in the camshafts and the phaser wheel oil seal rings were all good there, but I’ll replace them with the upgraded Mehenker parts anyways.
But before getting to that, I worked on setting the timing. I was able to get the front and top brackets mounted but the rear timing bracket is just off by a hair. My mechanic assures me this isn’t a big deal and is nothing to be concerned about but every video I see online, the tools fit on perfectly. So not sure if I need to fix the timing here…
Oh and I broke the coolant recovery tank hose while I was there turning the crank over. Can’t be too easy right
One step beyond.... so what are you thinking now you see it's unlikely seals related??
It would be great to find the issue now the beast is wide opened up for repair. We must focus on target issue: exhaust Camshaft position.
At this point something must be hidden in plain sight & overlooked...
> How is the chain tensioner oil circuit? If it drops enough pressure there's no enough left to counter camshaft jerkiness.
> VVT were rebuilt... Anyway the culprit is leaking pressure out or the opposite not venting to squeeze air out.
> Practical Challenge....
It's not trivial to translate the dynamic data + fault to a now resting static engine.
> EVIDENCE... We see camshaft traveling to both extreme positions as it gets unloked.
-- VVT has enough pressure to unlock but not enough to counter camshaft forces.
Can we say: this has to do with oil supply?
In that way a leak in intake VVT impact neighbor exhaust VVT.
Meaning it's a whole system: don't concentrate on exhaust side only.
It may well be that you're dealing with limited oil pressure to begin with. As we know, many ways to get low pressure and few get good pressure.
I think it is no coincidence here: Bank1 exhaust VVT gear is last to be served remaining oil pressure and HPFP/roller as well.
It's not yet as easy as parts swaping. On the flip sides the number of variables are limited. Proceed by elimination towards likely odds.
One last detail is causing this:
Should we inspect the Bank-1 tensioner then VVT gears themselves ? looking for leak ways
🤞
> Bigger circle around EXH VVT...
Can we get 100% sure its not exhaust side?
Oil pressure comes towards Bk1 Exh VVT then what...
VVT solenoids were swapped around right?
???Stupid: can reluctor seal shafts have been swapped exhaust/intake ???
(EDIT: Bk2 vs. Bk1: better oil distribution)
Last edited by CaliBenzDriver; Aug 11, 2025 at 05:41 PM.
Reason: is Bk2 (not Bk1)
One step beyond.... so what are you thinking now you see it's unlikely seals related??
It would be great to find the issue now the beast is wide opened up for repair. We must focus on target issue: exhaust Camshaft position.
At this point something must be hidden in plain sight & overlooked...
> How is the chain tensioner oil circuit? If it drops enough pressure there's no enough left to counter camshaft jerkiness.
> VVT were rebuilt... Anyway the culprit is leaking pressure out or the opposite not venting to squeeze air out.
> Practical Challenge....
It's not trivial to translate the dynamic data + fault to a now resting static engine.
> EVIDENCE... We see camshaft traveling to both extreme positions as it gets unloked.
-- VVT has enough pressure to unlock but not enough to counter camshaft forces.
Can we say: this has to do with oil supply?
In that way a leak in intake VVT impact neighbor exhaust VVT.
Meaning it's a whole system: don't concentrate on exhaust side only.
It may well be that you're dealing with limited oil pressure to begin with. As we know, many ways to get low pressure and few get good pressure.
I think it is no coincidence here: Bank1 exhaust VVT gear is last to be served remaining oil pressure and HPFP/roller as well.
It's not yet as easy as parts swaping. On the flip sides the number of variables are limited. Proceed by elimination towards likely odds.
One last detail is causing this:
Should we inspect the Bank-1 tensioner then VVT gears themselves ? looking for leak ways
🤞
> Bigger circle around EXH VVT...
Can we get 100% sure its not exhaust side?
Oil pressure comes towards Bk1 Exh VVT then what...
VVT solenoids were swapped around right?
???Stupid: can reluctor seal shafts have been swapped exhaust/intake ???
Well I haven’t really ruled out much yet as I’ve only been able to get access to the bank 1 timing thanks to this stubborn stripped screw. My issue is on bank 2.
Although I’m still unsure about the timing being a hair off. My mechanic assured me it’s fine as the ECU can adapt but I may still look at making it perfect just to rule that out as a potential cause.
Well I haven’t really ruled out much yet as I’ve only been able to get access to the bank 1 timing thanks to this stubborn stripped screw.
My issue is on bank 2.
Although I’m still unsure about the timing being a hair off.
My mechanic assured me it’s fine as the ECU can adapt but I may still look at making it perfect just to rule that out as a potential cause.
Bank-2 changes everything in a easier way!
It gets guaranteed good pressure served right after the pump unlike Bk1 served left-over pressure.
VVT gear is able to precisely compensate for chain wear in fractions of degrees. It can not deal with teeth-off discrepancies. So that timing is likely okay.
As far as I understand your top issue is ECU flagging Bk2 Exh. camshaft swinging out of control to both extremes, right?
++ I've crossed Bk1 from earlier post.
Last edited by CaliBenzDriver; Aug 11, 2025 at 06:12 PM.
Bank-2 changes everything in a easier way!
It gets guaranteed good pressure served right after the pump unlike Bk1 served left-over pressure.
VVT precisely compensate for chain wear in fraction of degrees. It can not deal with teeth-off discrepancies. So that part likely okay.
I believe the top issue is your ECU flagging camshaft out of control that swings to both extremes, right?
++ I've crossed Bk1 from earlier post.
Well the key signal is implausible camshaft angle on bank 2 exhaust. Which I also have a code for and further backed up by the live data logging during cylinder 7 misfires. Of course the critical components are serving to be the most difficult to get to…
My first trial of breaking this ground strap screw loose via JB weld was unsuccessful. Today I’m liberally applying acetone + ATF throughout the evening + hammering for vibration to hopefully allow the mixture to seep deeper in. Tomorrow I’ll apply full strength JB weld after roughing up the screw cap with a wire brush attachment for my Dremel and cleaning with brake cleaner afterwards prior to applying JB weld. That should give me the best shot of breaking it loose. If that doesn’t work then I think I’m either stuck with completely grinding down the screw cap off, or removing the front bumper, radiator, and fan.
I think I’d try removing the screw cap before I go the nuclear route of removing the entire front end and drilling it out.
Last edited by ZackaSnack; Aug 11, 2025 at 06:11 PM.
Well the key signal is implausible camshaft angle on bank 2 exhaust. Which I also have a code for and further backed up by the live data logging during cylinder 7 misfires. Of course the critical components are serving to be the most difficult to get to…
My first trial of breaking this ground strap screw loose via JB weld was unsuccessful. Today I’m liberally applying acetone + ATF throughout the evening + hammering for vibration to hopefully allow the mixture to seep deeper in. Tomorrow I’ll apply full strength JB weld after roughing up the screw cap with a wire brush attachment for my Dremel and cleaning with brake cleaner afterwards prior to applying JB weld. That should give me the best shot of breaking it loose. If that doesn’t work then I think I’m either stuck with completely grinding down the screw cap off, or removing the front bumper, radiator, and fan.
I think I’d try removing the screw cap before I go the nuclear route of removing the entire front end and drilling it out.
once had success tapping in a torx into a bolt head and shaft and getting the retained bolt shaft out of the socket - sounds like you similar ? I drilled about 6-7 mm into the shaft and hammered that torx into there that was 20% bigger than the hole I made
once had success tapping in a torx into a bolt head and shaft and getting the retained bolt shaft out of the socket - sounds like you similar ? I drilled about 6-7 mm into the shaft and hammered that torx into there that was 20% bigger than the hole I made
Yes I'm almost sure I could get the screw out if I could fit a impact drill into the space but it's too tight even for a 90 degree drill without removing the bumper, radiator, and fan. I've seen people have success with the JB weld method but it just will take a few days for everything to properly do it's job for the best chance of success. My first attempt, I didn't realize I used a quick curing JB weld and I don't think I properly prepared the screw surface as I didn't do any abrasion to allow for better adherence.
I dont have a visual on that screw position.... hopefully you can get it loose with a sharp chisel & hammer. Good luck.
We are searching for evidence of pressure loose at exhaust side only:
leaky tensioner...
mesh filter screen
(reluctor shaft O-Rings)
VVT gear issue (leaking / loose / hard)
solenoid actuator issue (jam)
(electrical connector issues cps/sol.)
Something's doin it ??
Oh yeah I've already tried hammering it. Thing doesn't budge even after applying Kroil penetrating oil. But like I've mentioned, giving it the best shot short of drilling the cap off or front end removal over the next few days.
But yes I'm checking all of these things.
The mostly likely points seem to be maybe chain tension or guides or reluctor oil seal rings. Filter screen has already been ruled out from previous work, although I'll still inspect it. The actuator has been proven to work through my manual testing having the same behavior across bank 1 and 2 and the electrical connections have no signs of corrosion or any other data pointing to voltage drops.
But again, leaving no stone unturned here. Something in the bank 2 VVT system is the culprit.
That’s a tough spot indeed. I was going to humbly suggest needle-nose vise grips grabbing the hell out of the cap, as I’ve gotten lucky that way before…but it doesn’t really look like you have enough room for a flush (sideways) approach with them either?
That’s a tough spot indeed. I was going to humbly suggest needle-nose vise grips grabbing the hell out of the cap, as I’ve gotten lucky that way before…but it doesn’t really look like you have enough room for a flush (sideways) approach with them either?
Correct. Here’s a closer photo which better displays this…
This is also after a few attempts to make a slot for a flathead via Dremel but the screw cap would just break away any time I applied any meaningful torque.
Anyways, feeling pretty good about round 2 of the JB weld method with better prep and full strength JB weld. Will report back after a couple days…
Funny goes this one screw has proven to have been more difficult to deal with than the rest of the job as a whole. Just a good learning experience I guess
Last edited by ZackaSnack; Aug 11, 2025 at 08:11 PM.
Boy do I feel dumb. I was chasing so hard to remove that destroyed screw cap, only to realize today that it didn't even need to be removed to remove that timing cover.... Wasted so much time with that thing and now the screw head is completely destroyed. Anyways... that's a problem for another time. At least the ground is still intact.
Now! The moment we've all been waiting for! I present! A dislodged phaser / reluctor wheel oil seal ring!!
On bank 2 exhaust, exactly where my symptoms have been pinpointed.
This weekend I will replace all these oil seal rings with the Mehenker parts, get everything all cleaned up, refill some coolant spills, oil change, and *fingers crossed*, she'll be purring along better than ever before.
Boy do I feel dumb. I was chasing so hard to remove that destroyed screw cap, only to realize today that it didn't even need to be removed to remove that timing cover.... Wasted so much time with that thing and now the screw head is completely destroyed. Anyways... that's a problem for another time. At least the ground is still intact.
Now! The moment we've all been waiting for! I present! A dislodged phaser / reluctor wheel oil seal ring!!
On bank 2 exhaust, exactly where my symptoms have been pinpointed.
This weekend I will replace all these oil seal rings with the Mehenker parts, get everything all cleaned up, refill some coolant spills, oil change, and *fingers crossed*, she'll be purring along better than ever before.
Congrats now that you have the fix bagged up. Inspection payed off. No parts necessary.
boy oh boy
> Root cause....
-- It is impossible for that ring to skip out of its groove.
-- HOW can this happen??
-- WHO last worked on that camshaft reluctor likely has something to do with this wild goose chase.
Timing jobs are not apprentice level...
Last edited by CaliBenzDriver; Aug 13, 2025 at 12:25 AM.
Congrats now that you have the fix bagged up. Inspection payed off. No parts necessary.
boy oh boy
> Root cause....
-- It is impossible for that ring to skip out of its groove.
-- HOW can this happen??
-- WHO last worked on that camshaft reluctor likely has something to do with this wild goose chase.
Timing jobs are not apprentice level...
No it’s possible. The mechanic where I’ve had most of my work done, and the last one who would’ve touched these parts, was the one who gave me a clue to check these specifically. He mentioned he’s never seen it but has heard from other mechanics of it happening. The M156 guru himself, Tasos Moschatos, mentions this in a couple of his videos as well.
Tried to link the exact timestamps, but in the first video, he mentions this at 7:14, 2nd video is mentioned at 28:45.
And I'm not so sure it was dislodged by the last shop that did the camshaft adjuster rebuild. It was as an issue (the hesitation behavior) before then, albeit not as bad, but it seemed to get progressively worse over ownership. My theory is that it didn't completely move out of it's guide right away but that it shifted over completely into the oil guide over time, hence why it progressively got worse. And during the adjuster job, it might've just gone unnoticed because it's so rare of a problem and these rings are very small.
Oh and parts were still necessary as at minimum I have to replace my timing cover and valve cover gaskets. I've also already got the supposedly improved seal rings from Mehenker that were designed to fix this exact problem. Going to swap to rings across all the phaser wheels. https://mehenker.com/en/camshaft-rin...-m156-amg.html
Last edited by ZackaSnack; Aug 13, 2025 at 01:24 AM.
My oh my... I think this saga might finally be over..
Got her all put back together short of topping off coolant and an oil change...
New phaser wheel oil seal rings installed bank 2 bank 1 Timing and valve covers reinstalled with new gaskets + spark plugs + coil packs Draining coolant New thermostat and temp sensor installed Coolant (overflow tank?) and hoses reinstalled Wiring harness and top-end all tidied up
Fired right up first time! Had some stored codes (from previous implausible camshaft position codes) that cleared and did not reappear. Got up to temp at idle with heat running for coolant bleeding. Got it all up and went for a test drive with everything up to temp.
No hesitation or cylinder faults logged! Even just cruising low speeds around the city when the previous behavior would've been very noticeable. I just took it very light except for one "medium" pull. All good!
Now I'm a little hesitant to say I'm in the clear for this car yet since I've yet to go on a proper extended drive across various conditions. Hoping my schedule and traffic tomorrow allows me to on a decent mixed condition drive.
I maybe also have some leaks. After topping off the coolant, I noticed what seemed like water dripping down while it was sitting in my garage idle. I used Zerex Pre-mixed coolant / antifreeze G48-50/50 which is blue so I'm a bit confused why the leaking fluid was clear. Definitely not gas.
There was also some smoke coming from the rear of the engine seemingly from around the end of the headers? Video: https://imgur.com/a/vU6WgEq It happened on both sides. It didn't seem to last forever so I'm thinking it was maybe just oil or coolant that leaked out a bit while I had everything taken apart. Although I'm wondering if it could maybe the new zip ties are burning on the wiring harness?
Last edited by ZackaSnack; Aug 17, 2025 at 02:42 AM.
No more water leaking or smoke. I'm thinking the water may have been condensation dripping down from running my heat full blast when bleeding the coolant. Guessing the smoke was some oil burning off that dripped down while I had the top-end apart.
Went on a couple more drives today in mixed conditions after an oil change and doing the camshaft teach-in adaptations. Everything ran smooth! It feels weird; it's like I'm only just now starting to feel the true nature of how this car should drive after owning it for almost a year now. Really felt the duality that is the M156 W212 today, getting out on the 5 for some "spirited driving", then cruising back home with the "massage" seats, music, and adaptive cruise control going. Amazing. Only thing I can really fault it for is that Comfort mode is not the smoothest as it feels like it's bogged down being in high gears, but this seems pretty normal from what I've seen reported from other users with the MCT trans.
But all is well so far! Given how difficult this was to diagnose, it almost feels too good to be true.
Well done, sir. This has been cool to watch you work through all this and is in our sticky to serve others on a similar journey.
enjoy the fruit of your hard physical and intellectual work.
oh, and regarding the comfort bogginess , you may just need to drive the car aggressively for the next one to 200 miles to adapt the comfort setting to your driving style. It may be as simple as that.
Last edited by PeterUbers; Aug 17, 2025 at 11:06 PM.
No more water leaking or smoke. I'm thinking the water may have been condensation dripping down from running my heat full blast when bleeding the coolant. Guessing the smoke was some oil burning off that dripped down while I had the top-end apart.
Went on a couple more drives today in mixed conditions after an oil change and doing the camshaft teach-in adaptations. Everything ran smooth! It feels weird; it's like I'm only just now starting to feel the true nature of how this car should drive after owning it for almost a year now. Really felt the duality that is the M156 W212 today, getting out on the 5 for some "spirited driving", then cruising back home with the "massage" seats, music, and adaptive cruise control going. Amazing. Only thing I can really fault it for is that Comfort mode is not the smoothest as it feels like it's bogged down being in high gears, but this seems pretty normal from what I've seen reported from other users with the MCT trans.
But all is well so far! Given how difficult this was to diagnose, it almost feels too good to be true.
...so after $12,000+ it was a free fix cuz some stuff fell out of socket??
dude i have nightmares about this stuff.. and i'm the one who gets paid to fix this s***. you know what man if you drive it for 5+ years all the costs average out and you have a mechanically museum quality car now
congratulations nobody deserves a good quality drive home in a fast car more than you bro. I legit stopped using MBworld for a couple months because of this thread due to how hopeless it was looking
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Just a good learning experience I guess
Wasted so much time with that thing and now the screw head is completely destroyed. Anyways... that's a problem for another time. At least the ground is still intact.
