6.2 AMG M156 camshaft timing

[cheddar]

Hi all.
Wondering if anyone here can share any experience with timing up this horrible setup. I have had repeat problems with this.
Have followed the guides I have to work with (autodata) which seems to correspond with the WIS document I found online, and carefully followed each step.
However, when all torqued up and done, I rotate the crank twice and the timing at at the back of the cylinder heads no longer slides in, it’s very close but enough to bring up codes for camshaft timing.
I have blamed my cheap copy timing tool set for not holding the cam’s securely allowing a tiny amount of twist when tightening the bolts but just wondered if anyone else has had a similar ordeal before?
This is on a 2008 CLK63 if it helps.
Thanks, Gav.

 

[jaymanek]

so you have a new chain?

 

[cheddar]

No, I didn't touch anything on the chain. I replaced 2x intake cams and all 32 tappets. There was never any errors stored at any time in my ownership of the car relating to timing so it must be something i've done.
I did use a boroscope before doing anything with the engine, to look down and see if there was any significant wear on the chain guides, all looked good so I was glad to leave that side of things in peace.
Cheers, Gav.

 

[Andyfkettle]

Not familiar with the setup your doing but always used to use a pulley holding tool to hold camshaft pulleys and never relied on a timing tool for torquing up, you maybe doing it right just my tuppence worth.

 

[cheddar]

yep, its an awkward setup, I know what you mean regarding pulley holding tools, but can't find a way to use something like that for this setup.
The camshafts have no keyways, and grip the driven pulleys by means of a diamond-coated washer. then there is the trigger wheels for the camshaft position sensors which can also turn and need to be held in position by a tool.
there is a camshaft holding tool in place when tightening the bolts, this holds both cams against each other as well as being bolted to the head. however I feel that it's tolerance for movement is higher than I would like. I have since ordered the genuine mercedes timing tools from my dealer, should be here soon.
I also feel like i'm missing a trick or tip with this engine though.
Thanks.

 

[Andyfkettle]

No worries. Hope you resolve it and be sure to let us know when you do!

 

[zenman63]

I found the cam holding tool across the cams and the bar across the slots in the ends more than enough, new washer every time.

 

[cheddar]

Hopefully my theory about the chonky timing tool set is righit then. will find out at the weekend when the 'proper' bits turn up.
And yep, i've gone through quite a few washers and bolts now, mercedes teesside parts dept have probably had enough of me now.
Cheers, Gav.

 

[cheddar]

Well, it’s been about 2 weeks since the ‘proper’ Mercedes tools arrived and I boshed it all together once again. And I can report that all is well, been using it daily since with no issues.
I would say the Mercedes cam holder tool is actually looser than the cheapo one but having 2 sets of tools made the job far easier.
I would also say maybe Mercedes themselves may make mistakes, as the car has never been worked on outside of their network until I bought it, I found this on the back of one of the removed camshafts:

 

[zenman63]

Looks like the tool slipped across the back of the cams chipping the cam undoing the front bolt.
Did you find the bit that broke off?

 

[cheddar]

This must of happened a long time ago looking through the car's history. Unfortunately I never found any bits, but I have changed the oil several times since I've owned it, could of been drained away in the oil.
I've also had both the sumps off recently, and found nothing but a few bits of rubber gasket in the pump strainer(s). I would of liked to find the missing piece but I'm quite satisfied it's gone or was picked out by the culprit who broke it.
The car seems to go a lot better than it used to, maybe the timing had been slightly incorrect for years, entirely possible if that happened when timing up, as long as the sensor disc was in the correct position then the ECU would think all is well.

 

[cheddar]

Also, I never left the bar in place when loosening the cam adjuster bolts, just checked they were the right way up and crank 40 degrees, so it defo wasn’t me.
At the time, I’d just removed the engine after finding this mess below, so was kind of expecting a full rebuild. The noise was pretty awful.

 

[Alex]

I’d be tempted to rebalance the damaged camshaft.

 

[zipdip]

Well the bit missing from the cam may well be NCU, no clean up,when the cam was machined,not sure if this cam would ever have been balanced,just how are you going to balance it,the cam looks like it has been through the wars,but if the engine is back together and running ok fine,what may surprise some people is that the cams in very expensive engines are given far less engineering expertise than a crank or a piston,I am not sure about MB but if you know a person or have owned a Jaguar with a straight 6 engine the cams fitted to those have never had the ramp or the nose checked electronically or the position of number one lobe to the keyway position,so they have no idea if the cam has the right profile.

 

[cheddar]

It does seem a shame to bin them. At the time I did have a thought which went along the lines of can you still get cams re-profiled, but maybe I read too much about the issue with these cams was more to do with poor quality materials. Funny how it only happened to the upper / intake cams and not the exhaust ones. There was noticeable lobe wear on approx 6 lobes of both intake cams, most the tappets had unusual wear patterns and a few were soft.

 

[cheddar]

I would add that when I bought this car, I viewed 2 others and they both sounded exactly like mine, I never thought there was anything untoward, now it’s had these bits done it’s much quieter.
Makes me think these problems manifest over quite a long time until the noise becomes more noticeable. The others both had lower mileage.

 

[Alex]

Well the bit missing from the cam may well be NCU, no clean up,when the cam was machined,not sure if this cam would ever have been balanced,just how are you going to balance it,the cam looks like it has been through the wars,but if the engine is back together and running ok fine,what may surprise some people is that the cams in very expensive engines are given far less engineering expertise than a crank or a piston,I am not sure about MB but if you know a person or have owned a Jaguar with a straight 6 engine the cams fitted to those have never had the ramp or the nose checked electronically or the position of number one lobe to the keyway position,so they have no idea if the cam has the right profile.

Balancing would be pretty straight forward - the same amount of weight would be removed from the opposite end (a dimple drilled out typically).

 

[Gledsyc63]

I'm currently debating whether to do this job myself. As mine is quite noisy and I have a small leak from one of the covers. Do you have a copy of the wis that you used and price of the MB locking tools. Anything to look out for if I was to tackle this. Thanks


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[merc85]

How many miles on this engine? what year ? Rubber gasket in the Oil strainer id be thinking someone may have been upto something with the lump.

Still glad you have got your head around it all now and its running spot on.

 

[cheddar]

It’s a 2008, 10 years old last week. There’s 91k on it now, problems for me started approx 500 miles ago. There’s a mention of warranty repairs when it was 2 years old done at Mercedes, I saw the cam adjusters were dated 2011 too, so not really sure. All the servicing and repairs were done within the Mercedes network until I bought it so you’d hope work was done correctly.
Defo glad to be driving it again though, I didn’t really want to put it back on the road till summer but my temp scrappy car died prematurely at 250k miles so I had to pull my finger out.