M271 cam adjuster/timing question

Grasscutter

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2004 C180K Classic SE
Grateful for some advice if someone can help. I have a S203 with the M271 engine in 180K guise on a 53 plate. It's covered a reasonably trouble-free 120K mostly motorway miles and up until now has been MB dealer serviced, but home fixed if anything has failed. I'm ex-motor trade, but these days not so keen on spending time under the bonnet. The car was well used by the first owner, a friend of mine, and I bought it at 2.5 years old with 80K already on the clock. Ever since I've owned it, there has been a noticeable rattle on start up until it got oil pressure - although it seems it was only ever me who could hear it as funnily enough, during the last of the warranty, the MB dealer never could.


I didn't take much notice and accepted this was a noise I had to live with, thinking hydraulic tappets etc. Naturally the rattle hasn't got any better and am now having sleepless nights after reading reports of worn timing chains, tensioners and chains skipping teeth. The car starts and runs fine, however, I'd like to do my best to keep it that way. I can't afford to replace it right now, so thought I should check the condition of the timing gear and carry out preventative maintenance in preference to leaving it and running into much more costly corrective maintenance later.


Lining up the crank pulley to TDC, I thought a reasonable check of chain wear would be to see if the cam timing marks line up. Indeed the inlet is pretty well spot on. However the exhaust is retarded, but not by as much as a tooth on the sprocket. The attached pictures show the error on the exhaust cam relative to the inlet.


I believe the sprockets have a locating pin aligning them into the cam, so it is not possible to offset them. Is this kind of deviation normal on the 271 or is the adjuster built into the sprocket faulty? I can't find much information on the adjusters, except my research has lead me to the MB bulletin, AF05.20-P-1401AG, titled "Rattling noises after starting engine until oil pressure has built up" Apparently there have been at least 3 revisions of the cam adjusters to improve tolerances, minimise oil loss to stop rattling at start up until the adjusters have oil pressure. There is nothing to show what's inside the adjuster, how it works and if it is possible for wear in these to upset the static timing. Can anyone help me with this? Maybe I have found the cause of the start up rattle, but is it something I could safely go on living with?
 

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veniemin

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mercedes
Hello

I have the same motor with 148tkm. Just measured the timing today gave kind of same results as yours.

I lined the inlet cam exactly on the mark, had the pulley about 2 degrees after tdc and the exhaust cam was a millimeter or so off the mark.

I have the nak-nak-nak sound on cold starts, but as I understand it, the sound comes from the cam adjusters not from the chain...

Did you have any work done on your engine?

What do you think of the cam sprockets do they look worn out in the picture?
 

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Grasscutter

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Hi Veniemin,

I've still not got a conclusion on this one. I'm now getting engine management fault codes relating to the cam adjusters and it has been suggested the timing error is confusing the ECU into thinking there is a fault with the cam adjuster magnets. I've got a chain kit on order with the tensioner and guides, so I'll see how I go on after fitting that.

I have to say I think the sprockets in your picture are showing signs of wear. The teeth aren't perfectly symmetrical - you can see which side of the teeth get the load from the chain. Whether it is bad enough to warrant replacement, I don't know. Unless someone can guide us to a cheap source, those sprockets are damn expensive.

What's still confusing me most with mine is the fact the inlet cam and crank pulley timing marks are spot on, but the exhaust cam is noticeably off. I would like to see inside the cam sprocket/pulley to know if there is anything that can wear and cause the timing shift. I'll let you know the result after the new chain.
 

goldbird

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I having exactly the same rattle on startup.Where can I find this bulletin? "Rattling noises after starting engine until oil pressure has built up" ?
Grasscutter did you change the timing chain yet?

 

SchwarzesAMG

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CLK W209
Every M271 i heard starting from cold, does the same noise for a couple of secs (+/- due to the different oil i suppose)

As for the exhaust cam, i have seen in my engine (M271.940) with Star that timing is a bit delayed, so i suppose that if i take a look i will see pretty much what you see!
So when you change the timing chain pls keep us posted!

In my friends shop its very typically to see worn out timing chains on M271s around 120-140000km, customers are told so, some of them do change the chain, some say they dont mind and they come back after some time with the valves on their hands :p

My engine was built around '05 and it has about 83K kms! I could hear the noise from day one :)
But what makes me suspicious about the chain is that the engine is a tad louder/harsh-ier than it was some years ago, some say that the sound is more "brutal" and they like it, but i am just going around to see what could be replaced and keep it running good for much longer!

PS Some days ago i saw an E-Class E200 W211 MY2004 with 340000km, the owner did only oil changes, spark plugs and nothin more engine-wise :)
 

shorty

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My E class has the 271 engine , its done 190,000 km , Ive noticed a rattle on start up sometimes when the car is warm . The chain was changed at around 140,000 km by the last owner . Should I be worried about this rattle ? I havent checked the chain or sprockets condation yet
 
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Grasscutter

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Well, some blood, sweat and fortunately not too many tears later I have a new timing chain, tensioner and two of the three guides replaced. To change the third chain guide (on the inlet side of the engine) looked to require the whole of the front timing cover to come off, something I wasn’t about to do as the guide had only very slight wear. I connected the new chain to the old and carefully turned the engine, trying my utmost to keep both cams in sync with the crankshaft. A few heart-stopping moments as of course the cams tend to spring forward when a valve is closing. The official MB tool keeps the chain in mesh with the sprockets, but I didn’t have that luxury. Once the new chain was through, disconnected the old chain and rivited the link joining the new chain.

The result is the inlet cam timing mark is again spot on with the crankshaft at TDC, but the exhaust cam is still retarded. Comparing the alignment now in the latest picture below with that in the original post, it is improved to what it was. Just to show it’s not possible to get it any better, the other picture below shows the cam advanced by one tooth on the sprocket – way advanced and out by a bigger amount. Note these two latest pictures only show the exhaust cam.

One thing I should have photographed was old the chain itself. I kept thinking it was my eyes, the chain seemed slightly 'skewed' in the short section between the two cam sprockets as if the side of the chain towards the front of the engine was slightly longer than the side of the chain at the back of the engine. Wear marks on the back face of the sprockets confirmed what I was seeing was actually true. I think that was enough evidence alone to convince me to change the chain and I’d encourage anyone with the M271 on more than 100K miles to think about replacing the chain. The whole job, chain, tensioner and guides didn’t set me back much over £150, so I’d reckon it was a good insurance. I’d bought a chain kit, but it doesn’t include the various expansion plugs you have to sacrifice to get at things like the tensioner, so be prepared to do a bit more shopping. I also took the opportunity to change the coolant.

Regarding the rattle at start up, I don’t think I’m noticing anything different with the new chain. I can understand the adjuster in the sprocket rattling as what little spring pressure there is holding it back against the end stop would be overcome as the cam springs forward when valves close, only to be forced back against the end stop again when the next valves are pushed open, all until it gets oil pressure anyway. I would liked to have changed the sprockets, but without significant wear to the teeth, I just couldn’t justify the cost. If anyone has an idea why it isn’t possible to get the timing absolutely spot on or if this is just typical of the engine, please can they let me know?

Goldbird – that bulletin I mentioned about the rattling cam adjusters, I had sight of the MB workshop manual. I’m not sure how I’d stand over copyright to post it here. Perhaps someone could advise me?

And the bad news: the new chain didn’t fix the intermittent P0020 engine management fault it was getting. I have solved that by other means - details in a separate post.
 

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goldbird

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Nice work Grasscutter! So if I understood correctly we can now say for sure that the 1-2 sec rattle during startup when the engine is cold is due to cam adjusters.That is probably why Mercedes replaced those parts twice...
The thing is that they are very-very cheap(only 1500 euro both :doh: ) so I think I will also change only the timing chain.... :dk:
 

colifecape

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Hi,
I have slight play on the inlet sprocket relative to the camshaft. Not much but enough to annoy me.
Currently its stripped out due to a skipped chain tanning the valves.....

Coli
 

kevkanic

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Jan 24, 2012
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Grand Cherokee
Exhaust Cam fault

Hi

I have a problem exactly the same as you guys have been discussing that I just cant seem to get to the bottom of.

We have an E class 2003 1.8 with the 271 engine. I have a returning fault code pointing to exhaust cam position. It does not set at idle, just in the 2-3k rev range normally. We have checked the cam timing and like the pictures posted on here the exhaust cam is fractionaly retarded and the inlet lines up spot on. I dont believe the fault to be a stretched chain as this would also cause the inlet timing to be incorrect.

We have tried swapping the VVC units from cam to cam and it also has new cam magnets (replaced due to oil leaks along with the wiring harness) and we have also replaced the cam postion sensor with a new OE one.:confused:

Is there something I am missing here ?

Any help would be greatly appreciated !
 

shorty

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Have you checked the chain , it may be stretched , the adjuster is on the exhaust cam side so this would take out any slack and keep the exhaust cam inline .
When my car started giving trouble it was with a fault for the intake cam sensor . The cause if the problems was the chain had stretched , I had to replace the cam sprockets as well , the cost over 700 euro each .
 

kevkanic

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Hi Shorty

With the crankshaft on tdc the inlet, which is on the longest side of the chain lines up exactly Yet with just a short piece of chain between the inlet and exhaust cams the exhaust cam is slightly out of alignment, this is why I dont feel it can be a chain issue.
 

E200TK+

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Fault code P0020

I have the same error code on my E200TK 2005 model. The orange fault indicator came up a few weeks ago and I called the local MB dealer. They told me to drive carefully and deliver the car for repairs when convenient. After the orange fault indicator appeared I noticed the engine temperature was never going higher than about 65-70 degrees (outside air temperature -5 degrees). When the outside air temperature rises to about 10, the yellow fault indicator disappears. When I yesterday delivered the car I was sure I would be an easy fix, probably just to replace the engine’s thermostat. But the local MB dealer told me the fault code they found indicated "A" Camshaft Position Actuator Circuit fault. For sure this would be expensive! Anybody else that have experienced the above, low engine temperature and yellow engine fault indicator (P0020)?
 

WG M-B

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The stat maybe causing the engine to run cool. But the timing issue which is causing the mil to come on is separate.
It's chain and tensioner time. And if you are unlucky you may need gears too
 

hotch743

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"Heck yes" same problem with my 271 Merc engine. 71k chain stretched all exhaust valves bent. So, fitted a new chain and tensioner re did all the valves and fortunately borrowed a Merc cam set tool. My timing marks are the same as the photo, but has the same faults noisy top end on cold start and engine fault light which after diagnosing says "cam timing fault".
I am not a qualified mechanic but the engine runs perfectly, i believe.
The noisy top end could be oil draining out of the hydraulic valve adjusters. Anyhow after all the cylinder head work 1000m later No4 piston big end knocking so new crank and shells. 271 all done runs. "Quality Mercedes" !!!
 

BlackC55

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I expect it has been very low on oil at some point. The oil light is not very sensitive and people do not check the level often enough or use the correct oil.
 

WG M-B

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As above. The bottom end is usually reliable
 

ronancooney

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w211
Hello

I have the same motor with 148tkm. Just measured the timing today gave kind of same results as yours.

I lined the inlet cam exactly on the mark, had the pulley about 2 degrees after tdc and the exhaust cam was a millimeter or so off the mark.

I have the nak-nak-nak sound on cold starts, but as I understand it, the sound comes from the cam adjusters not from the chain...

Did you have any work done on your engine?

What do you think of the cam sprockets do they look worn out in the picture?
Hi just searching for some info on these sprockets and what tolerances they should be changed at.... did you change the ones in that pic or have you had any updates on them since?
Thanks
 

clk200komp

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how did you fix it? I have motor error light on and service look with star diagnostic they said your car have timing problem. one day before the error they change the motor oil filter and camshaft magnet sensor o rings only. Im thinking the magnets or another sensor can do it. I have not chain sound on my car. what do you think it? regards.
 

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