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Hi,
Been trying to resolve this for a while but progress.
Its not the camshaft timing adapters as I have had 2 of them fail before and it is a different sound to that (plus camshaft adjusters were loudest on cold start)
I have replaced both timing chain tensioners, upped the oil from 5w-30 to 5w-40 (synthetic and still within mercedes warm climate specs) , but the 2 to 3 second loud rattle remains on warm startup only.
Chatgpt says don’t worry about it ? But is a really bad sound. Car has done 160,000kns but hasn’t missed a 10,000km oil change
Your VVT unit is already bad.
VVT = cam phaser or cam adjuster sprocket and its oil control valve to be replaced both.
You have 4 +4 of these, usually two will go bad first.
This VVT has a service life and not a lifetime component like crankshaft.
The noise comes from the VVT adjustable parts hitting its left and right or clockwise and counterclockwise end stop and also from the lock mechanism pin failing to lock.
Watch below :
The genius who decided to run 5W-30 oil for 10k.Km in warm climate increased the service cost of your engine.
You'll want to have all 4x VVT gears diagnosed for having loose locks.
> FURTHERMORE....
"5W-40 Euro" is not huge viscosity... it's bare bone oiling to help save gas from less oil friction.
You could get you intake valves inspected/cleaned up from the burnt 5w-30 carbon deposit.
Any engine codes related to camshafts timing correlation mismatch (reluctor shifted) ??
Don't be surprised when your unbalanced engine condition lands in the ballpark of misfirings and vibrations regardless of all new ignition components, totally normal.
Last edited by CaliBenzDriver; Apr 21, 2025 at 12:02 AM.
Thanks for the ideas,
I had 2 cam adjusters replaced last year due to severe rattling on cold startup.
This is a different sound, exactly same as in the YouTube video.
Car runs perfectly (is a 2014 not 2914 !) and no codes .
Only issue is after parking for 15+ minutes I get the bad rattle for a few seconds.
Maybe I should try some expensive 10w-50 ?
Or Lucas oil stabilizer ?
Go back to that shop, get them to use Xentry VVT logging to read the angles of all 4 VVT during start up.
With that sound, you will have a whacky reading of at least -10 to +10 degrees OFF from target.
Make sure their Xentry is a fast one of at least 4-5 readings per second. Or else logged values can be misleading aka wrong.
INTAKE VVT does not move during cold start. It is not commanded to move by ECM. OFF below in pink means my engine is OFF.
I logged from dead engine>>> to crank to start >>> to running engine. 120 seconds only is the log by default.
Your INTAKE VVT last year, had a failed locking pin, thus it MOVES a lot and make rattle. You replaced it already, so its good now.
--------------------
Exhaust VVT moves during engine start, be it warm or cold.
From its parking position of -23 or -25 degrees it will immediately go to -5 degrees.
This time..... your EXHAUST VVT wants some love, they are jelous of the new intake VVTs ....thus EXHAUST NOW had the noise because it overshoot too much.
These 4 VVTs share similar work load, thus they wear out almost equally....sort of.
This is my educated guess and I am sure it is what is going on.
Test with the xentry and get the log like in my post , you post it here and I will help you analyze it.
Good luck....
Last edited by S-Prihadi; Apr 21, 2025 at 06:02 AM.
I'll get the Xentry Log done if it gets any worse or at the next service.
I have a good independent mechanic I use in Melbourne who has Xentry, but he still isn't particularly cheap as labor In Australia is at ridiculous levels.
As an example, when I had the intake cam adjusters replaced, the cost came to just under AUD10,000 (about USD 6,000). This would nearly exceed the value of the car if I had to do it again - so I doubt I would do it.
I replaced the 5w 30 with 5w 40 and it made no difference, so I agree must be the exhaust cam adjusters. I wish the mechanic replaced them when he replaced the intake.
I replaced the 5w 30 with 5w 40 and it made no difference, so I agree must be the exhaust cam adjusters. I wish the mechanic replaced them when he replaced the intake.
It may be your exhaust VVT lock are worned out by 5W-30 extra low pressure: lock unlock lock unlock all day long!
you can use a scanner to read fault codes and live correction factors.
I'll get the Xentry Log done if it gets any worse or at the next service.
I have a good independent mechanic I use in Melbourne who has Xentry, but he still isn't particularly cheap as labor In Australia is at ridiculous levels.
As an example, when I had the intake cam adjusters replaced, the cost came to just under AUD10,000 (about USD 6,000). This would nearly exceed the value of the car if I had to do it again - so I doubt I would do it.
thanks again
Digger11
I feel you...I know...
Thus DIY it makes more sense
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....thus EXHAUST NOW had the noise because it overshoot too much.
