Free guide · 2008–2014 · M156 6.2 V8 · 457–487 PS
Mercedes C 63 AMG W204: what to check before you buy
What this car is, and the six questions that decide whether the one you are looking at is a good buy.
In this guide · 6 chapters
Who built it, and what they built
AMG put a 6.2-litre naturally aspirated V8 into a compact saloon, and then never did it again.
The M156 is the engine this whole series exists to talk about. It is AMG's own big atmospheric V8 — hand-built, 6,208 cc, 457 PS, or 487 PS with the Performance Package, revving to 7,200 rpm. The C 63 that replaced this one went to turbochargers, and everyone who owns one of these knows it.
And it is a C-Class. Four doors, a boot, back seats. That combination — a hand-built 6.2 V8 in an ordinary compact saloon — is the joke at the centre of this car and the reason it will never be repeated.
One gearbox, and no choice about it
Always the 722.9 seven-speed automatic. A manual was never offered. So an advert offering a manual C 63 is describing something else.
Within that there is a real distinction, and it matters more than most people realise:
2008 to 2011: AMG Speedshift Plus 7G-Tronic — a conventional torque converter automatic, with Comfort, Sport and Manual modes.
Facelift, 2011 to 2015: AMG Speedshift MCT — a wet start-off clutch instead of a torque converter, plus an S+ mode. It shifts faster, and the sources note it is prone to overheating under hard use.
Hold on to that, because the chapter on years and specifications shows you why it is the other half of a trade.
The number on the boot
The badge says 6.3. The engine is 6,208 cc. AMG rounded up rather than down, in honour of the 6.3-litre V8 of the sixties — and there is no better one-line summary of the culture that produced this car.
How the figures in this guide work
No euro totals: a labour rate differs by country and by workshop. Each job carries a step on a scale of five — an hour or two, half a day, a day, two or three days, a week or more in the workshop — plus one line on where the work sits.
Where a source gives a figure it is quoted as given. On this car one figure matters more than any amount of money, and it is not a price: it is the engine serial number. The buying guide explains which number, and why.
The six questions that decide whether this car is a good buy
1 · What is the engine serial number?
The head bolt problem has a cut-off, and it is an engine serial number, not a model year. Below it, the car can have the weak bolts; above it, it cannot. Sources do not even agree on the last affected model year, so the year alone is not an answer; the number is. Which number, and how to get it before you travel, is in the buying guide.
2 · Is the coolant level right, and what colour is the expansion tank?
This is the cheapest early check for the head bolts, and on this car the coolant tells you more than it does on most. What the warning sign looks like, and why it is so easy to explain away, is in the buying guide.
3 · What mileage is on it, and have the camshafts been looked at?
Premature camshaft wear is a known M156 weakness, and specialists advise planning for replacement as maintenance. At what mileage, which camshafts, and what evidence to ask for are in the buying guide.
4 · How much oil does it use?
Mercedes' own C-Class owner's manual gives a figure for what the car may use, depending on driving style. Use it in both directions: do not panic at topping up, and do not accept a figure well beyond it as character. The figure, and how to ask for the car's own, is in the buying guide.
5 · Is it a pre- or post-facelift, and which gearbox?
7G-Tronic to 2011; MCT after. If it is an MCT car that has seen track use, ask about heat.
6 · Any brief limp mode that clears on restart?
It is a known pattern on this gearbox, and it leaves nothing behind that you can feel on a test drive. What causes it and where to find its trace is in the buying guide.
What the honest answer to all six looks like
An early car with an engine serial number above the cut-off is the sweet spot: no bolt risk and the simpler gearbox. A documented facelift with camshaft work behind it is the other good answer. A car whose owner cannot tell you the serial number and tops up coolant "now and then" is the one to price very carefully indeed.
Which years, which specification
2008 to 2015, and the facelift lands in 2011. Most guides tell you to buy a late one. That advice is half right, and the half it misses is worth money.
Because the two halves of this car swap their problems.
| 2008-2011 | Facelift 2011-2015 | |
|---|---|---|
| Head bolts | at risk, unless the engine serial number is above the cut-off | largely behind it |
| Gearbox | 7G-Tronic Speedshift Plus, conventional torque converter | Speedshift MCT with a wet start-off clutch and S+ |
| The catch | the bolt question has to be answered | the MCT shifts faster but runs hot under hard use |
So the best car is not simply the newest one. It is an early car whose engine serial number sits above the cut-off — because that combination gives you the simpler gearbox and no bolt risk. Those cars exist, and adverts sort them by model year rather than by serial number.
A facelift is the other good answer, and an easier one to find. You are trading a resolved engine question for a gearbox that wants respect on a hot day.
On power: 457 PS as standard, 487 PS with the AMG Performance Package. Check which package a car actually has: one buying guide describes a Performance Pack that left the engine as it was, with only the Performance Pack Plus bringing 487 PS. The Package is worth having if it is there and not worth paying a fortune to find.
What it is worth
No price list — it moves by country and by month. What matters here is that this car has one binary question and one maintenance schedule, and the market prices neither of them correctly.
The binary question is the serial number. It is free to answer, it takes minutes, and it is the difference between a car at risk of the most expensive repair on this list and a car that is not. The market prices on model year instead, which means an early car with a good serial number can be undervalued and a late car over-trusted.
The maintenance schedule is the camshafts. Wear failures cluster around a known mileage, per the sources, and specialists advise treating replacement as regular maintenance. A car with that work documented is worth real money more than one without — and again, the market largely ignores it.
There are three kinds for sale.
The documented car. Serial number known, coolant history clean, camshaft work either done or not yet due. Pay for it.
The tidy car with a story. Presents beautifully, and both of the above are unknown. Buy it on the assumption that the camshafts are coming, and do not buy it at all until you have the serial number.
The cheap one. On a C 63 the reason is almost always coolant, camshafts, or a seller who does not want the engine looked at. All three are knowable.
What it is actually like to own one
A 6.2-litre naturally aspirated V8 that revs to 7,200 rpm, in a car you can park anywhere and put children in. Very few cars have offered that, and the C 63 that replaced it went to turbochargers.
What it asks in return is that you treat two things as scheduled rather than as surprises: the coolant, and the camshafts.
The habits that cost almost nothing:
- know your engine serial number, and write it in the folder
- check the coolant level and the colour of the expansion tank monthly, not annually
- know what it uses in oil, as a number, and compare it against the figure in the owner's manual
- on an MCT car, watch the temperatures on a hot track day rather than afterwards
What surprises people is that the frightening item is the cheapest to investigate. Head bolts sound like a catastrophe and they can be — but whether your car can even have them is a number stamped on the engine. Very few expensive faults in this series can be ruled out for free.
The buying guide — €24
Everything above is what the car is. This is what you check.
Seven faults that belong to this engine, taken apart one by one, with how much work each repair is and how to tell which of them you are looking at. Eight things that are simply fifteen years old, every one with how much work it is, what tells you about it at a viewing, and whether it has to be done now, within a year or two, or not at all. What a W204 shell does with age, and why it is not the story here. The head bolts: which engine serial numbers are affected, and how to find yours. The viewing in seven steps, including the two moments that come only once. The sentences you say to the seller, and how to build an offer out of what you found.
And a card you print and take with you — eighteen lines, in the order you do them. That comes as a separate file, because nobody wants to print a whole guide to take a few pages to a car park.
This is what one of the eight looks like
3 · Engine mounts
Half a day · the part Vibration at idle, a clunk pulling away. Feels structural, is not, and it is one of the cheapest items on this car. A rough, uneven idle is a different symptom; see 5.4.
And this is how the card reads
- 2 · The coolant · before the engine is started
- 3 · The cold start
- 4 · The oil
- 5 · The read-out, at a specialist
- 6 · The test drive
- The two questions that decide it
What €24 buys, put next to what it saves
The repair for failing head bolts is a week or more in the workshop. Whether your car can have them comes down to an engine serial number — and reading it costs nothing. The guide is €24. It will not stop any of that from being needed — but it does tell you which of them you are looking at before you agree a price, and that is the whole of the difference between paying for a car and paying for someone else's postponed maintenance.
Why there are no prices in it
Because a price we cannot verify is worse than no price, and because a price would be wrong for most of the people reading this anyway. Workshop rates across Europe differ widely, and so do parts prices. A quote from a specialist in one country tells you nothing in another.
What does not change is how much work a job is — that follows from what has to come off the car. So every point in the guide says whether it is an hour or two, half a day, a day, two or three days, or a week or more in the workshop, with a labour figure where a source gives one. And it says whether the money sits in the part or in getting to it, which is what lets you tell a fair quote from a bad one.
If you want a figure, ask any workshop one question — what is your hourly rate? — and every effort level in the guide becomes your own number, in your own currency. One question, and the answer is actually true for you.
How this guide was put together
Because you should know before you pay for it.
- Every fault and symptom comes from a source the guide names, the manufacturer's own documents first. The effort levels are our assessment, unless a source gives the hours.
- The two halves of this car swap their problems — early cars have the bolt risk and the simpler gearbox, late cars the reverse — and the guide gives you that trade instead of telling you to buy a late one.
- The effort of every job is counted item by item and checked against the list before every edition.
- It says as plainly what you can leave alone as what you have to do. None of the eight age points start from leave it.
Leave your email address at the checkout and both files arrive straight away: one guide and one card, as two pdfs. No subscription, no account.
The full guide · €24
17-page guide, A4 and phone · 3-page inspection card · instant PDF · VAT included
Have every car inspected before you buy by someone who knows this engine. This is general information about the model and not advice about a specific car.