M156 queries

[Rich764089]

Hi all, sorry to resurrect some M156 questions, but looking for some advice and couldn't find exact answers.

Are head bolts on a 2012 C63 better and therefore lower risk than earlier M156s? I know risk is probably over egged, but just curious to know this.

Also, how could an amateur like me identify issues with lifter buckets and cam adjuster plates, if at all?!?

Car has 14 MB services so not unduly worried... Though over 90k miles.

Thank you!

 

[Petrol Pete]

"Some of the main issues that linger in all M156 models consist of failure of the crankcase breather valve. The most common issue with the breather valve is that the diaphragm on the valve deteriorates over time. Another issue with the breather valve is that the hose from the crankcase to the valve also deteriorates and starts to crack. These issues can cause excess oil burning, heavy smoke from tail pipes and misfires. Other common issues are premature wear of engine lifters and camshafts as well as cam shaft adjusters. Common signs of this is a ticking noise at cold start of the vehicle. Other common issues consist of intake manifold failure, head bolt issues in models from 2007 to 2011 and drive belt pulleys."

From Wikip, so not necessary fact. About 9 minutes into the second video he shows how the head bolts can be seen once the valve cover is off . In the first video Alex shows the black series cam buckets being used , which are a different colour from stock.

I would think a 2012 would have the new headbolts . It can be checked via the engine number. Intresingly in the second video he implies that the headbolt failures were on lower mielage engines and very high milers . So if they have not gone on an average motor they should be OK ?

IMHO thats a bit of a risk.

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[Rich764089]

Excellent thanks.

 

[Petrol Pete]

Excellent thanks.

I made an edit . ( mins in second vid head bolts can be seen with cam cover off . Not sure if any potential seller would let someone 'pop' the valve cover off for a quick look .

Workshop receipts and photos ??

 

[Rich764089]

Thanks Pete. No record of any engine work, so I'll try to view it ASAP and listen for any unhappy engine noises ASAP!

 

[Rich764089]

Well I did my YouTube training to learn the sound from dodgy cam adjusters and the car has it, so the car is a no go unfortunately.

Is it about £3k to sort roughly?

 

[TrueSpirit]

From the tiny bit of research i did, most of the engine issues are top half issues. Cam lobe wear, lifters, buckets, magnesium manifold corrosion etc. 1 second rattle from the cams on cold start will sometimes help identify some of the cam issues but not all.

The headbolts were changed after engine serial number 60-060,658 or thereabouts. The sign the bolts are gone is coolant levels dropping or coolant in oil and oil in the coolant etc and when you see check engine lights etc

You'll also need to change engine mounts every 40k miles or so as they start to leak and sink (doing the transmission mounts at the same time is worth doing). you can get other mounts that wont need to be replaced that regularly.


Also as preventative work such as changing the fuel injectors is worth doing as they can stick and flood the engine.

PCV breather valve is a known issue and can be replaced if you're taking out the magnesium manifold, the plastic can get brittle and break and leak etc

The engine manifold is made of magnesium and these can corrode etc

Lastly the transmission itself can be problematic. I've got issues with mine and taking the car back to the dealer to get them to look at it

 

[Rich764089]

From the tiny bit of research i did, most of the engine issues are top half issues. Cam lobe wear, lifters, buckets, magnesium manifold corrosion etc. 1 second rattle from the cams on cold start will sometimes help identify some of the cam issues but not all.

The headbolts were changed after engine serial number 60-060,658 or thereabouts. The sign the bolts are gone is coolant levels dropping or coolant in oil and oil in the coolant etc and when you see check engine lights etc

You'll also need to change engine mounts every 40k miles or so as they start to leak and sink (doing the transmission mounts at the same time is worth doing). you can get other mounts that wont need to be replaced that regularly.


Also as preventative work such as changing the fuel injectors is worth doing as they can stick and flood the engine.

PCV breather valve is a known issue and can be replaced if you're taking out the magnesium manifold, the plastic can get brittle and break and leak etc

The engine manifold is made of magnesium and these can corrode etc

Lastly the transmission itself can be problematic. I've got issues with mine and taking the car back to the dealer to get them to look at it

Thanks - that's really helpful. I think the bolts are OK for this FL...?

I'm not too concerned about the MCT box as it's been serviced and handles 1050nM in my E63 fine.

I think it's the cam issues that are most concerning from my Googling....

 

[Rich764089]

I'm now doubting myself - anyone able to confirm this noise on start up is what I thought above please.....?

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[Skd884]

I'm now doubting myself - anyone able to confirm this noise on start up is what I thought above please.....?

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Perfectly normal.

 

[Rich764089]

Thanks... Just scaring myself then
I thought there was a rattle!

I've obviously watched too many YouTube videos that seem to describe this slight clatter on initial start up as cam adjuster issue...

 

[Bobby Dazzler]

The M156 is a noisy engine - in fact all AMG engines are noisy - and that doesn’t sound like it has notable issues. A caveat I must mention though is that it’s very difficult to hear on a video.

I have heard an M156 in real life which had a single lifter bucket and cam lobe wear and the tick was a lower pitched, slightly louder and less frequent tick, to what you can normally hear.

I suspect that is because the wear will likely only affect one (or small number of) bucket/lobe at first, and so the other 15 will sound normal, and hence you only hear one in every sixteen.

An expert will correct me if I am wrong, however I believe that evern healthy buckets are noisier initially as they are hydraulic pressure which takes a few moments to build and oil to circulate.

If a bucket sticks then it takes even longer to build pressure and so the tick persists for longer, and once it fails then the bucket becomes physically damaged and the noise becomes very evident.

An expert will no doubt correct me if that’s wrong.

Edited to add: General rule of thumb:

If the ticking is consisnet and generally reduces in volumes after a second or two then it’s probably fine at the moment.

If there’s an “odd” tick which is lower pitched, less frequent and persists longer then there’s probably an issue.

 

[Rich764089]

Thanks, very helpful!

Yes, I realise video diagnosis is difficult, hence probably coming to the won't conclusion myself! Also realise AMG engines are also quite noisy, which makes it very difficult for non experts like me, particularly when not familiar with the specific engine (at least not up close and personal).

Thanks again for the helpful steer and info; I think I'll try to go and have another look/listen...