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Zero driving done between 0, 1 and 2. Based on fellow forum members input, does sound like a cam adjuster.
I have a JB4, scanned the codes. No codes. The car does seem to lag on building boost initially (sometimes). I replaced the vacuum pump diaphragm last year. Haven’t rechecked it.
For the cam adjusters, appears you can replace without removing the cams (assuming the cam plate hasn’t shifted). Looks like they make a tool to lock the adjuster gears, to be able to remove them. Adjusters (non-MB) and tool available on Amazon.
Thanks, that’s a potential positive, and appreciate the diagnostic guidance. Saw the posts in the parallel thread, maybe I’ll do the oil pump mod, and an oil change too.
Thanks, that’s a potential positive, and appreciate the diagnostic guidance.
Saw the posts in the parallel thread, maybe I’ll do the oil pump mod, and an oil change too.
That can help going forward but what's done is done.
Truth being told: I think you have a very mild case so far - You're catching this early instead of ignoring it until camshaft-reluctors are shifted: max repairs.
Ok, I’m back. I decided to purchase the tensioners, cam sensor extensions and Motul 5W-40.
I’ll tell ya, I found it very hard to find clear procedures for these tasks. A lot of videos, but details are spotty!
So, for timing marks, at 53 degrees, I believe you’re supposed to see half the cam adjuster? That seemed to be the case for 3 of 4. Bank 1 (passenger side?) exhaust looked different than the others. Rotated the crank several times (by the way, getting the intercooler out of the way was a PITA, thanks @TwoC400s for your video!). None of the cam adjusters snapped/shifted, so I kept moving forward.
Rotated the crank to 40 degrees. I replaced the passenger side tensioner, seemed to go just fine.
On to the driver side, removed the tensioner bolts, it got jammed in the gears when it popped. Finally got it out. However, trying to put the new one in, the arm that the tensioner pushes against is way to the left, making it impossible to fit the tensioner. Thinking that was the reason it was hard to remove the old one.
Thoughts here? I believe the timing should be at 40 degrees for the drivers side too? I’m afraid to rotate it without the tensioner. Thanks!
Just to follow up. I found a few articles that indicate you can rotate it with the tensioner out. So, rotated 360 degrees. It dropped right in! Rotated it a few more times, all the timing marks seem to line up. Covers back on, just need to remount the intercooler and add oil, and should be all set. Fingers crossed!
I also did the oil solenoid mod, so hopefully I’m good to go for a while.
Thanks for sharing updates. Just to confirm my understanding. You did not have any timing off and did the tensions update, upon restart was the noise gone?
Hey Matt. I let the sealant cure overnight, so first start was tonight. Very loud rattle on start up, then cleared up. Restarted a few mins later, no noise. I plan to start in the am. I think that will be the true test. New Motul 5W-40 oil and MB filter. Also did the oil solenoid mod.
I did take pics of each of the cam positions while the crank was at 53 degrees…they all look good, maybe the passenger side exhaust is slightly off. Was hard to get a straight on pic.
Here’s the pics, starting from passenger side exhaust, intake, drivers intake, exhaust. I’ll post the videos too.
Last edited by Darrington; Aug 4, 2025 at 10:58 PM.
Hey, sorry, missed your posted! Unfortunately, still getting some intermittent rattle on start up. Not every day, but still happening. I need to snap another video to share.
I keep checking the JB4 for codes, but no codes. Not sure if the JB4 can see all codes, or just some. I also posted some logs on their forum, they said everything looks good.
I wish it wasn’t such a pain to access the crank, so I could get the pulley at 53 degrees, check the timing marks and rotate to see if lock pins are working.
More to come soon, just haven’t had a chance to troubleshoot more…
Originally Posted by MatthewJ
@Darrington Hows it doing now that you replaced those parts? Any more clatter on cold starts?
Hey, sorry, missed your posted! Unfortunately, still getting some intermittent rattle on start up. Not every day, but still happening. I need to snap another video to share.
I keep checking the JB4 for codes, but no codes. Not sure if the JB4 can see all codes, or just some. I also posted some logs on their forum, they said everything looks good.
I wish it wasn’t such a pain to access the crank, so I could get the pulley at 53 degrees, check the timing marks and rotate to see if lock pins are working.
More to come soon, just haven’t had a chance to troubleshoot more…
Hey Matt. I let the sealant cure overnight, so first start was tonight. Very loud rattle on start up, then cleared up. Restarted a few mins later, no noise. I plan to start in the am. I think that will be the true test. New Motul 5W-40 oil and MB filter. Also did the oil solenoid mod.
I did take pics of each of the cam positions while the crank was at 53 degrees…they all look good, maybe the passenger side exhaust is slightly off. Was hard to get a straight on pic.
Here’s the pics, starting from passenger side exhaust, intake, drivers intake, exhaust. I’ll post the videos too.
I double checked this pics....
I see passenger/Bk1 EXH is messed up
I see driver side /Bk2 is all spot on time.
The shortcut is to look at positioning live while engine is at 650.Rpm idle and 1k. Rpm...
Let's try to spot a wobbly VVT gear position using your scanner on ECU data.
Typically BK2-INT is the leading bad VVT
the comes BK1-INT comes in 2nd worst
then EXH adjusters.
Worned out VVT lock pins are caused by low oil pressure around 1200.Rpm
Last edited by CaliBenzDriver; Aug 24, 2025 at 07:07 PM.
Thanks, appreciate the analysis and recommendation (as always). So an Autozone type scanner will get the job done, or should I grab one off Amazon?
Doesn’t seem like this is something the JB4 can do…however to be honest, I haven’t gone further than to simply have it try to ‘read codes’ in the JB4 app.
Thanks, appreciate the analysis and recommendation (as always). So an Autozone type scanner will get the job done, or should I grab one off Amazon?
Doesn’t seem like this is something the JB4 can do…however to be honest, I haven’t gone further than to simply have it try to ‘read codes’ in the JB4 app.
I don't know JB4 tool... if it can read ECU data then there's a chance it can read each camshaft correction factors to see which one ends up in the weeds while oil pressure is still marginal.
On AMZ... lookup "LAUNCH CREADER ELITE MB" fairly good deal, likely overnight delivery. Cheaper in CN mart.
Ignoring the VVT rattling is what shifts the reluctor plates off their spot to cause correlation faults -- Not what makes these engine hum
Last edited by CaliBenzDriver; Aug 24, 2025 at 11:33 PM.
JB4 can scan and read codes, it cant give sensor data, and most if not all of the autozone ones would be in the same boat.
You would need a MB specific scanner that can see other modules and read live sensor data.
I too have an occasional startup knock and rattle. Started about a month ago, im at 99k miles. Only does it when the oil is hot and can drain down, and i restart. Not normally in the mornings.
I just did an oil change last night since i was at 4600 miles, it was about due anyway. Hoping that will help.
@Darrington did you add the oil restrictors/check valve to the tensioners as well or does our year already have them?
JB4 can scan and read codes, it cant give sensor data, and most if not all of the autozone ones would be in the same boat.
You would need a MB specific scanner that can see other modules and read live sensor data.
I too have an occasional startup knock and rattle. Started about a month ago, im at 99k miles. Only does it when the oil is hot and can drain down, and i restart. Not normally in the mornings.
I just did an oil change last night since i was at 4600 miles, it was about due anyway. Hoping that will help.
@Darrington did you add the oil restrictors/check valve to the tensioners as well or does our year already have them?
Oil specs can help or hurt the VVT phasers. Even in good condition engine can rattle.
I remember my second MB schedule oil change was late by a month and my low mileage VVT rattled with hot oil restart.
Hot thin oil bleeds right out of perfectly ok VVT + Tensioners. Preserving lock-pins from wear is a reason for more effective oiling.
Last edited by CaliBenzDriver; Aug 25, 2025 at 03:38 PM.
Good intel, thanks Matthew. Looks like I’ll take the plunge on a scanner off Amazon. I need to do some research, ratings don’t seem great on a few models.
I think our C400s have the restrictors? I think I checked the engine number. Here’s a pic as well.
Originally Posted by MatthewJ
JB4 can scan and read codes, it cant give sensor data, and most if not all of the autozone ones would be in the same boat.
You would need a MB specific scanner that can see other modules and read live sensor data.
I too have an occasional startup knock and rattle. Started about a month ago, im at 99k miles. Only does it when the oil is hot and can drain down, and i restart. Not normally in the mornings.
I just did an oil change last night since i was at 4600 miles, it was about due anyway. Hoping that will help.
@Darrington did you add the oil restrictors/check valve to the tensioners as well or does our year already have them?
Interesting. So that’s driver side intake. Wish I took the same pic on the passenger side. Pass exhaust is the one where the timing mark is off in the peephole.
Originally Posted by CaliBenzDriver
oil rushing out
Oil forced out of a defective VVT Phaser is a telltale sign of it having a bad lock pin.
-- the first time VVT is manually rotated clockwise oil gets forced out (pic.)
-- the second time you can hear a straight snap because no VVT oil is now empty.
The forward motion is applied by the camshaft force driven by valves.
Interesting. So that’s driver side intake. Wish I took the same pic on the passenger side. Pass exhaust is the one where the timing mark is off in the peephole.
Yes, a picture would have been helpful.
Now you can look at live timing data to assess the situation without intake disassembly. Saves real time.
If it rattles... data are going to evidence it with your scanner!
Last edited by CaliBenzDriver; Aug 26, 2025 at 01:14 AM.
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