Mercedes M273 Engine for Sale: 7 Proven Checks to Avoid a Bad Buy

If you’re searching for a Mercedes M273 engine for sale, your V8 Mercedes is probably not running the way it should, or not running at all. Maybe the check engine light came on with cam timing codes, maybe there’s a rattle on cold starts that keeps getting louder, or maybe a workshop has told you the idler gear has worn out and quoted a number that made your stomach drop. Whatever happened, an S550, E550 or GL450 with a good body and interior is worth keeping. Putting a healthy engine in is usually far cheaper than replacing the car.

We’re NJ Global Auto Parts. We sell used and rebuilt engines and ship them worldwide, and the M273 V8 is one of the Mercedes engines we’re asked about most. This guide covers everything we’d tell you on the phone about a Mercedes M273 engine for sale: the two sizes, full specs, which cars use it, what we test, what goes wrong, what it costs, how shipping works and what your mechanic should do on fitting day.

Straight talk, no padding.

What You’re Getting With a Mercedes M273 Engine for Sale

The M273 is Mercedes’ naturally aspirated petrol V8 from the mid 2000s. It came in two sizes, 4.7 and 5.5 litres, and it replaced the older three-valve M113. It has four valves per cylinder, twin overhead cams per bank, variable cam timing on intake and exhaust, and an aluminium block and heads. It’s the V8 sibling of the M272 V6 and shares a lot of design ideas with it.

On the road, it’s a lovely engine. Smooth, strong from low revs, and quiet when you want it to be. It pulls a heavy S-Class or GL like it weighs half as much. That’s exactly why so many owners look for a Mercedes M273 engine for sale instead of giving up on the car when the original fails.

For a list of variants and years, the Mercedes-Benz M273 engine page is a useful reference. For buying, your VIN and the serial number on your engine matter far more.

Mercedes M273 Engine for Sale: Full Specifications

These are the figures buyers ask about most when they enquire about a Mercedes M273 engine for sale. Exact outputs varied slightly by model and market, so use them as a close guide.

Engine family	M273 (E46 and E55)
Layout	90 degree V8, petrol
Valvetrain	DOHC per bank, 32 valves, variable intake and exhaust cam timing
Block and heads	Aluminium
4.7 litre (E46)	4,663 cc, bore 92.9 mm x stroke 86 mm
4.7 power and torque	Around 250 kW (335 hp) and 460 Nm
5.5 litre (E55)	5,461 cc, bore 98 mm x stroke 90.5 mm
5.5 power and torque	Around 285 kW (382 to 388 hp) and 530 Nm
Compression ratio	Around 10.7:1
Intake	Variable length intake manifold with tumble flaps
Cam drive	Timing chain
Fuel	Premium unleaded
Production	2005 to around 2013

The 5.5 is the more common one in most markets and the one most buyers want. The 4.7 was used mainly in models and markets where tax or fuel costs made a smaller V8 attractive.

Which Mercedes Models Use the M273

S-Class (W221): S450 and S500 / S550
E-Class (W211 and W212): E500 and E550
CL-Class (C216): CL500 and CL550
CLS (C219): CLS500 and CLS550
CLK (C209 and A209): CLK500 and CLK550
SL (R230): SL500 and SL550
ML (W164): ML500 and ML550
GL (X164): GL450, GL500 and GL550
R-Class (W251): R500
G-Class (W463): G500 and G550 from around 2008

Rear-wheel drive, 4MATIC and SUV versions don’t all share the same sump, oil pickup and accessory layout. Send us your VIN before you buy any Mercedes M273 engine for sale, and we’ll match the right variant.

How the 4.7 and 5.5 Compare in Real Life

Both are strong engines. The 4.7 in a GL450 or S450 is plenty for most drivers and uses a little less fuel. The 5.5 has noticeably more pull, especially when overtaking or towing, and it suits the heavier cars better. Fuel economy between the two isn’t as different as you’d think, because the bigger engine works less hard.

Our advice is simple: replace like with like. Swapping a 4.7 for a 5.5 is possible in some cars, but the engine software, gearbox calibration and sometimes the exhaust and cooling need attention. It’s rarely worth the hassle unless you plan it carefully.

4MATIC, SUVs and the G-Class: Extra Things to Check

The M273 went into everything from a two-door SL to a G-Class off-roader, so the engines aren’t all dressed the same way. On 4MATIC cars the front driveshaft runs close to the sump, so the oil pan and pickup are often different from rear-drive versions. The ML, GL and R-Class share some parts but have their own accessory layouts. The G-Class has its own cooling and intake arrangements because of the boxy engine bay.

None of this is a problem when the engine is matched to the car properly. It just means you shouldn’t assume any 5.5 V8 will bolt straight in. If you’re buying a Mercedes M273 engine for sale for an SUV or a 4MATIC car, tell us the exact model and we’ll confirm the sump, mounts and ancillaries before you pay.

If the car tows, also tell us that. Towing puts more load on cooling and on the timing chain, so we’ll point you to the best unit we have for that kind of use.

Inspecting a Used M273 Yourself

If you’re able to see an engine in person before buying, here’s what we’d look at:

Oil filler cap and inside the cap area. Heavy sludge suggests long oil change intervals, which is hard on chains.
The cam magnets on the front of the heads. Oil around them or in their connectors is common, but heavy wetness needs attention.
The intake manifold. Look for broken linkages and listen for rattles when you move it.
Spark plug tubes. Oil in the plug wells points to seal leaks.
The front cover and timing area. Look for signs it’s been opened, and ask why if it has.
Coolant passages. Any brown sludge or oil residue is a warning.

Most buyers can’t travel to inspect an engine, which is why we send detailed photos, the serial number and test figures with every Mercedes M273 engine for sale we quote.

Replace or Repair? What Makes Sense on an M273

Some M273 faults are easy fixes. A leaking cam magnet, a cracked breather hose or a failed thermostat don’t mean the engine is finished. But the bigger jobs on this engine are labour-heavy.

The idler gear job on early engines is the best example. On many cars, the engine has to come out to do it properly. By the time you’ve paid for removal, parts, timing tools and reassembly, the price gap between fixing your engine and buying a good Mercedes M273 engine for sale is often small. Add in the risk that a high-mileage engine might need more work later, and replacement starts to look like the safer bet.

Get a repair quote and a replacement quote and compare them honestly.

Used, Rebuilt or Long Block

Used engine

A used M273 comes from a running car. It’s the most affordable choice and suits buyers who want value and are willing to replace seals and service parts while it’s out.

Rebuilt engine

A rebuilt M273 should come with a new timing chain, guides, tensioner and the updated idler gear parts on early engines, plus fresh gaskets and seals. It costs more, but it takes away the main worries.

Long block or complete

A long block is the core engine. A complete Mercedes M273 engine for sale includes more bolt-on parts like the intake manifold, sensors and sometimes the alternator and AC compressor. Our guide on rebuilt vs used engines explains the trade-offs.

7 Checks We Make on Every Mercedes M273 Engine for Sale

Engine serial number. This tells us whether it’s an early or later unit for the idler gear issue.
Compression test. All eight cylinders, looking for strong, even readings.
Cam timing history. Where possible we check for stored cam and crank correlation codes.
Timing chain noise and visible wear.
Oil condition. Clean oil, no coolant, no metal.
Leaks. Cam magnets, valve covers, oil cooler, filter housing and rear main.
Photos and records. You see the actual engine and its number before you pay.

If an engine fails any of these, it doesn’t go on our list as a Mercedes M273 engine for sale.

Common M273 Problems Worth Knowing

Idler gear and sprocket wear

Like the M272, early M273 engines had a sprocket in the timing system that could wear too soon. The chain loses accuracy, cam timing drifts and the car throws codes like P0016 or P0017, sometimes with a rattle. Later engines used an improved part. That’s why we check the serial number on every Mercedes M273 engine for sale.

Timing chain and guide wear

Chains stretch and plastic guides wear over time, especially with long oil change intervals.

Intake manifold flaps

The tumble flap mechanism inside the intake can wear or break, causing rough running and codes.

Oil in the wiring

Leaking cam adjuster magnets can push oil along the harness. Fix it early before it reaches the ECU.

Oil leaks and cooling parts

Valve cover gaskets, the oil cooler seal and the thermostat are common wear points. Spark plug tubes can also seep oil.

For more on choosing a replacement, read our post on used M273 engines with warranty and our M273 V8 replacement engine guide.

How to Tell the Old Engine Is Finished

Before you start shopping for a Mercedes M273 engine for sale, make sure replacement is the right call. These are the usual signs:

Jumped timing or a failed chain
Low compression on one or more cylinders
Bottom end knocking
Metal in the oil or a spun bearing
Overheating damage with coolant in the oil
An idler gear repair quote close to the cost of a replacement engine

What Comes With a Mercedes M273 Engine for Sale From Us

Photos of the exact engine and its serial number
Compression results
A clear list of what’s attached
Mileage information where available
Written warranty terms
Proper crating for shipping

You can go straight to our Mercedes M273 engine product page to request a quote.

Questions to Ask Any Seller

What’s the full engine serial number?
Is it an early or later unit for the idler gear issue?
Were there stored fault codes when it came out of the car?
What were the compression readings?
Is it from a 4MATIC or rear-drive car?
Is the intake manifold included?
What does the warranty cover?

Any honest seller of a Mercedes M273 engine for sale should answer every one of these without hesitation.

Where to Find Your Engine Number

On most M273 engines the serial number is stamped on the block on the left side, near the back of the engine where it meets the gearbox. It starts with 273 followed by the variant code, such as 273961 or 273963, and then the individual serial. It can be hard to see without a mirror and a torch, and it’s often covered in grime.

If you can’t find it, don’t worry. Your VIN is enough for us to work out which variant your car came with. The engine number is still useful though, because it tells us whether your old engine was an early unit and helps us explain what probably went wrong. Send a photo if you can get one.

A Quick Note for Workshops and Trade Buyers

Independent Mercedes specialists make up a big part of our M273 orders. If you fit these engines regularly, talk to us about trade terms. We can find the exact variant you need, keep you informed when good units come in and ship several engines together. Many of our trade customers also buy M272, M276 and M278 engines through the same account.

How Much Does a Mercedes M273 Engine for Sale Cost?

We don’t publish fixed prices because stock changes constantly. What affects the price:

4.7 or 5.5. The 5.5 is usually in higher demand.
Used or rebuilt. Rebuilt costs more but includes new timing parts.
Early or late serial number.
2WD or 4MATIC configuration.
Complete or long block.
Delivery destination.

Send us your VIN and country and we’ll quote a Mercedes M273 engine for sale delivered to your door.

Shipping a Mercedes M273 Engine for Sale Worldwide

We ship to North and South America, Europe, the Middle East, Africa, Asia and Oceania. Every Mercedes M273 engine for sale we send is drained, sealed, strapped down and crated or palletised. Sea freight to your nearest port is the usual route. Air freight is available if you’re in a hurry.

Import duties and taxes depend on your country. The World Customs Organization has general background on how goods are classified, and a local broker can confirm the real numbers. Our shipping policy explains the rest.

Fitting Advice for Your Mechanic

Replace or transfer the cam adjuster magnets and check the harness for oil.
Fit a new thermostat and check all coolant hoses.
Fit new spark plugs and inspect the coils and plug tubes.
Replace the engine and gearbox mounts if they’re tired. They often are.
Prime the oil system before the first start.
Inspect the intake manifold flaps if you’re reusing your old manifold.
Use the correct Mercedes-approved oil and coolant.
Clear codes and check cam and crank correlation values after start-up.

Keeping the New Engine Healthy

Buying a Mercedes M273 engine for sale is only half the job. To get the best life from it:

Change the oil more often than the long factory intervals. Chains last longer with clean oil.
Don’t ignore a check engine light, especially cam timing codes.
Fix oil leaks before they reach wiring or the exhaust.
Keep the cooling system in good shape. Plastic parts age.
Listen for rattles on cold start.
Let the engine warm up before driving it hard.

M273 vs M272 vs M278: What’s the Difference?

The M272 is the V6 version of the same basic design. It won’t replace an M273 without major changes. The M278 is the twin-turbo V8 that replaced the M273 from around 2011. It’s more powerful and more efficient, but it uses different electronics, mounts and cooling, so it isn’t a simple swap either. In practice, the right replacement for an M273 is another M273 of the right type. Our post on M272 vs M273 differences covers more.

Running Costs After the Swap

A healthy replacement M273 resets a lot of the costs that pile up on a tired engine. Fuel use usually improves, because an engine with timing faults burns more fuel. Misfires and rough running go away. Most importantly, you stop worrying about whether the car will make the next trip.

Plan to spend a little extra on common ageing parts while the engine is out: mounts, hoses, belts, the thermostat and plugs. They’re cheap now and expensive later.

How to Order a Mercedes M273 Engine for Sale

Send us your VIN and delivery country through our contact page.
We match you to the right Mercedes M273 engine for sale and send photos, the serial number and a delivered quote.
You confirm and pay according to our billing terms.
We crate and ship it, then send tracking.
Your mechanic fits it using the advice above.

More Mercedes Engines From NJ Global Auto Parts

Browse our full range of Mercedes engines or the whole used engine catalogue. Related engines:

Why Buy From Us

With the M273, buyers worry about the same things: getting an early engine with a worn idler gear, getting the wrong variant for their car, and paying for something that never shows up. We deal with those worries head on. You see the real engine, you get its serial number, compression figures, a written warranty and tracked shipping. Read more about us and our refund and returns policy.

When you compare every Mercedes M273 engine for sale you find, look at the serial number, the test results and what’s actually included, not just the price.

Frequently Asked Questions

Is the M273 a reliable engine?

Later engines and well-maintained early engines can be very reliable. The idler gear issue on early units is the main weakness.

How do I check if a Mercedes M273 engine for sale is early or late?

Ask for the full engine serial number. We’ll tell you what it means for that engine.

Will a 5.5 replace a 4.7?

Sometimes, but software, gearbox calibration and other parts may need work. Replacing like with like is easier.

Can a 4MATIC engine go in a rear-drive car?

The sump and oil pickup are different on many models. They can sometimes be swapped, but ask us first.

How long will a replacement M273 last?

A healthy M273 with regular oil changes can easily pass 250,000 km and often a lot more. The ones that fail early tend to be the ones that skipped services or ran for months with timing codes.

Do I need special tools to fit it?

A good workshop with Mercedes diagnostic equipment can do it. Cam timing tools are needed if the timing system is disturbed during the swap.

How long does delivery take?

It depends on where you are and whether you choose sea or air freight. We give you an estimate with every Mercedes M273 engine for sale quote and send tracking once it ships.

Do you ship worldwide?

Yes, by sea and air to most countries.

Does the engine have a warranty?

Yes. We confirm the terms in writing before you pay.

Get a Quote on a Mercedes M273 Engine for Sale

A big Mercedes V8 sitting in the driveway costs you every week. Send us your VIN and country, and we’ll come back with photos, a serial number and a delivered price on a Mercedes M273 engine for sale that fits your car. Contact us or visit the shop.