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I am comparing the amount of shaft out from the tensioner.
This I believe can also tell a few things :
01. How much stretch overall on the chain.
02. If VVT phaser locking or not ( engine OFF )
03. Or maybe less powerful spring/pressure at the tensioner ( but engine is OFF ) if say tensioner push shaft can't pop out more ?
04. Or Maybe state of oil check valve ?
My car when at approx 36,00KM , now 40,000KM. RIGHT BANK TENSIONER.
Right side image is from youtube : I do Cars channel. 30,000 miles C43 engine. M276.825
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The C43 engine tensioner pop out a tiny bit more than mine. In theory any worn out chain guides (plastic) will also make tensioner pops out more.
This C43 engine has one of the guide tip broken, a tiny bit but at LEFT bank.
.
The one from GOAT garage , his push shaft pops out like 1CM or 1/2" more than mine. But his Intake VVT is bad, not locking when engine OFF.
MY LEFT BANK TENSIONER
This is where the tensioner push the timing chain guide.
For long term preventive maintenance, I can actually make a peep hole for the tensioner.
Machined the mini VVT magnesium cover for M10 female thread. I then use tough PA66 nylon M10 screw with sealant. Nylon wont corrode magnesium.
I can then use my 6mm and 8mm boroscope camera to see tensioner push-shaft travel every few years.
PA66 is oil resistant and will survive constant 120C easy.
I like your idea of inspection hole a lot
Being abble to quickly peek inside with your bore scope is priceless.
Make sure the hole location let your borescope look at VVT during lock-pin testing of intake + exhaust... or multiple peep holes... swiss-cheese.
installation / shaft wear marks
Here we can see the shaft wear marks... the shaft is traveling loosely in/out under low pressure!
Even low pressure without leak should keep shaft from backing inside... failed seal!
Tip: you know how everything is just finger tight with these aluminum assemblies... When you install new tensioner let the spring pressure push the tensioner against its two screws then tighten screws under stress.
✌️
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by S-Prihadi
Its not paranoid ... , its more of predictive & preventive maintenance. The 2 el-cheapo seals will leak guaranteed 100%, but when ? That is the tough question.
If those 2 el-cheapo seal does leak coolant into my oil, I will ruin my engine and I would have failed my own predictive & preventive maintenance to keep running well for as long as I can, minimum 20th year of age.
Replacing coolant more often will not help with how the polymer/rubber seals would degrade over time.
I replace coolant latest once per 5 years. In fact I am on my 3rd coolant already. 1st one from MB was the old yellow coolant. So I replaced the blue one twice.
I also have replaced the coolant expansion tank , because it will crack and the reason MB coolant can last that long is because inside the coolant expansion tank there is a bag
of chemical which its job its to inject additive over time to make the coolant long life. The Audi has that too.
Also my timing for LEFT intake is 1.27* adapted, that means there is that much degree of a timing chain stretch or the tensioner is not healthy enough
OK, this is mine for the M276.825 (SL400). I will check my M276.957 next for comparison. I wish Mercedes would publish what the acceptable range of values is. How do we not know the correction factor for the left intake cam is not "normal"?
I believe 6 degrees is BAD.
Our flywheel is equal to 60 tooth. So 360/60 = 6 degrees. So a 6 degrees is like jumping 1 tooth.
I personally would replace chain + all guides and tensioner by 3.5 to 4 degrees, if I don't worry of that timing cover coolant seal potential to leak into oil .
Yes, sadly there is no info on timing stretch limit in WIS
What an informative thread. People are faking anything nowadays. From the video of the fake chain tensioner you posted it's pretty clear that it doesn't work lol.
01-15-2024, 03:05 AM
