M271 engine timing chain and camshaft sprockets

[Olivier31]

Hello all,

Long story short, on my 140000km 2011 1.8 turbo C 180 I had an engine light that would disappear then come back and a fault code pointing at the intake camshaft sensor which I changed but no improvement. Tthen I heard a short diesel sound for one second every now and then and starting would take a couple of seconds more than it should.
I decided to open up and fit a new chain and tensionner.
I’m almost done but there is one thing annoying me which i’d Like to double check with expert advice please:
I attach pictures of my camshafts markings before and after, I am happy with the all the markings bar one, the one on the outboard of the intake camshaft sprocket is not aligned with the one on the inboard ( camshaft side) of the same sprokef assembly , is it normal or an issue?
The Mercedes documents to check alignment says :
The camshaft adjusters (3) require no particular adjustment, as they automatically take on a basic position to the camshafts when engine is vertical

Can I crimp my chain and fit my tensionner or do I need to fit a new intake sprocket assembly? ( they seem pricey)


Before new chain intake side:




Exhaust side before:



Exhaust side after:




And the one that annoys me, intake side after, you can see the markings on each side of the chain is not fully aligned.


Cheers guys,

Olivier

 

[Olivier31]

The merc document I referred to if it helps

 

[Tonygw]

I think the M271 is renowned for timing gear failure. It could well need more than just a tensioner unfortunately.
There is a sticky thread on this forum somewhere but its very well documented.

 

[Tonygw]

The Complete M271 Engine thread. ( Revised and Updated ) | Engine

The Complete M271 Engine thread. ( Revised and Updated ) People are forever asking about how to mod their M271 C180 Kompressor so I thought some work was required to help guide us all! Hope this helps someone. The Complete M271 Engine thread. As you know a number of people regularly...

forums.mbclub.co.uk

 

[markjay]

The timing gear on later M271 engines fails in a different way to the earlier ones.

On earlier engines the issue started with worn camshaft sprocket wheel teeth. On later engines the issues was caused by a failure of the hydraulic tensioner (oil pressure leak).

The camshaft sprocket wheels on your engine can be reused if there's no sign of wear on the teeth.

The timing chain, and hydraulic tensioner, and the plastic guides will need to be replaced.

Sorry but I don't know the answer to your question re the timing marks alignment.

 

[Olivier31]

Thank you Tony and Mark I read all that with atttention, the teeth of my sprockets look absolutely fine, hence I’m still puzzled as to if I need to order a new intake sprocket or not.

 

[kth286]

Is your car not a W204 with 271 evo engine? Your instructions show different models.

You probably need AR05.20-P-7201CW (remove/install cam adjusters)

 

[Olivier31]

Thank KTH286, indeed I was not showing the good reference. However there is the same statement with reference to the alignement, I wonder is I need to remove the camshafts sprocket and check if the positonning pin (1 on the picture) is not broken and the sprocket has moved.

 

[Olivier31]

Hello
I will answer my own question and maybe it will be useful for someone else later:
I decided to reopen the chain ( I had not crimped it yet on purpose) and test the adjusters for free play, the exhaust side is nice an tight, the intake (i.e. the one with the annoying alignement) can rotate a few degrees. Ref the video I made:

Intake Camshaft adjuster

I have opened it, not much to see, the inside looks very much like the one in this video which had the same symptoms than mine if you watch the previous video on this guy’s channel. Clearly the pin and spring do not do their job anymore which explains the transitory rattle noise when the oil pressure is low during start and the camshaft sensor code.

Open camshaft adjuster

Conclusion I have ordered a new intake adjuster and the bolt ( which includes the valve system) that I damaged when I removed it. And that hopefully will allow me to put everything back in order!