Car Model Guide/ Mercedes-Benz/ M-Class/ W164/ ML 320 CDI

ML 320 CDI OM642

The V6 diesel. Effortless and long-lived, with two known age items: the oil cooler seals beneath the intake, and the swirl-flap linkage.

Overview

The ML 320 CDI is the OM642 diesel version of the Mercedes-Benz M-Class SUV (W164), sold 2005–2011 with 224 PS and auto_7g. High risk at level 4. The oil cooler seal leak needs the intake off, and air suspension failures are dear on a car this heavy. 7 failure modes are recorded against its engine, gearbox, chassis and shared components, one of which is a walk-away item without documented proof. Prices on this page are illustrative placeholders rather than a sourced market sample. See the methodology for how the bands are derived.

Mercedes-Benz M-Class SUV (W164) · photo Mercedes-Benz W164 black by Thomas doerfer · CC BY-SA 3.0 · Wikimedia Commons

Power224 PS

Torque510 Nm

Years2005–2011

Fueldiesel

Drive4MATIC

EnginesOM642

Biggest risks

Ranked by probability × repair cost. 7 recorded in total.

29High risk

M272 balance shaft gear wear (early petrol V6)€3,000–€6,000partly checkablewalk away
Airmatic strut and compressor failure€600–€3,000checkable
Oil cooler seal leak€900–€1,600checkable

Risk level −33 · Walk-away failures −12 · Likely spend vs price −26 · all issues →

System by system9 systems reviewed · 4 with no recurring fault reported

Engine⚠ attentionM272 balance shaft gear wear (early petrol V6), €3,000–€6,000. Walk away without proof.+1 more in this system

Fuel system✓ clearNo recurring fault reported for this system on this engine.

Intake & airwatchIntake-port shut-off (swirl) actuator failure, €400–€900.

Cooling✓ clearNo recurring fault reported for this system on this engine.

Emissions⚠ attentionDPF clogging and forced regeneration, €250–€1,800.+1 more in this system

Transmissionwatch7G-Tronic conductor plate and 13-pin connector leak (722.9), €400–€900.

Electrics✓ clearNo recurring fault reported for this system on this engine.

Suspension & brakes⚠ attentionAirmatic strut and compressor failure, €600–€3,000.

Body & interior✓ clearNo recurring fault reported for this system on this engine.

Pre-facelift or facelift, this engine spans both

The same badge either side of the changeover. Bands are split at the facelift year from the generation record.

Phase	Years	Low	Average	High	Good buy	What differs
pre Pre-facelift	2005–2007	€5,500	€9,000	€14,000	€7,250	The specification the car launched with.
LCI Facelift (LCI)	2008–2011	€6,000	€9,800	€15,250	€7,900	New nose, lights and interior; 7G-Tronic across the range; Revised suspension tune

Known issues, ranked by expected cost

Faults recorded against this engine, its components and its chassis, ranked by likelihood × repair cost. Costs are indicative ranges with a stated labour basis.

M272 balance shaft gear wear (early petrol V6)W164 body€3,000–€6,000

A camshaft position fault code, a rough or lumpy idle, and a check engine light that returns after clearing. Balance shaft gears on M272 engines built inside the early range wore prematurely against the crankshaft gear. Later engines used a revised gear, so the engine number decides the risk rather than the mileage or the service book.

Check: Take the engine number and check it against the affected range before you look at anything else, because no amount of service history answers this. A stored camshaft correlation code is the other warning.

Later parts: Revised balance shaft gear on later production engines

EngineoccasionalPartly detectablewalk away without proofevidence: manufacturer80–200k km

Airmatic strut and compressor failureW164 body€600–€3,000

The car sitting low after standing, a message on the dashboard, or a compressor that runs far longer than it should. The struts perish and leak, and the compressor then runs continuously until it burns out. Cars used for short trips and left standing suffer first, because the bags crack where they fold.

Check: View the car cold and before it's been started, then cycle every ride height and watch all four corners respond. A compressor that runs on after levelling is the early warning.

SuspensioncommonDetectable at viewingevidence: documented90–180k km

Oil cooler seal leakOM642 3.0 V6 CDI€900–€1,600

Oil weeping down the back of the block, burning smell, oil in the valley beneath the intake. The oil cooler sits in the vee under the intake manifold and its seals harden with age. Access requires the intake off, so labour dominates the bill.

Check: Look down the back of the engine with a torch for wet oil and fresh cleaning. A suspiciously spotless engine bay on a 200,000 km V6 deserves a question.

EnginecommonDetectable at viewingevidence: documented150–280k km

DPF clogging and forced regenerationDPF€250–€1,800

Warning light, limp mode, oil level rising above the maximum mark from fuel dilution. The filter needs sustained hot running to regenerate. A car used for short urban trips never completes a regeneration cycle.

Check: Read the DPF soot load and the distance since the last regeneration on a scan tool, and check the engine oil level and smell it for diesel. Ask what the car was used for. A short-trip city diesel is the wrong car regardless of mileage.

EmissionscommonPartly detectableevidence: documented120–250k km

7G-Tronic conductor plate and 13-pin connector leak (722.9)Mercedes 7G-Tronic seven-speed automatic (722.9)€400–€900

Harsh, delayed or jerky shifts, holding a gear then banging the next in, and limp mode, often with speed-sensor or gear-ratio fault codes. The speed sensors in the conductor plate (mechatronic) fail, and/or the external 13-pin connector leaks fluid that wicks up the wiring into the control unit. Early units are the most affected.

Check: Test-drive through every gear cold and warm. Scan the transmission, and pull the external 13-pin plug to check for fluid on the pins.

TransmissioncommonPartly detectableevidence: documented120–220k km

EGR cooler leakEGR cooler€400–€1,000

Coolant loss with no visible external leak, white smoke, sweet smell. The EGR cooler cracks internally and leaks coolant into the intake. BMW recalled affected diesels over a fire risk from glycol deposits igniting.

Check: Check coolant level and look for unexplained top-ups in the service history. Verify the recall was carried out. It's free and searchable by VIN.

EmissionsoccasionalPartly detectableevidence: manufacturer120–250k km

Intake-port shut-off (swirl) actuator failureOM642 3.0 V6 CDI€400–€900

Limp mode and power loss, usually with fault code P2015 stored. The actuator motor that drives the intake-port shut-off flaps in the manifold fails, frequently after being shorted by oil dripping from the turbo-inlet seal above it; the flaps or linkage can also seize.

Check: Scan for P2015 and related intake codes; a car that has thrown it before is likely to again unless the oil-leak cause was addressed.

Turbo & intakeoccasionalDetectable at viewingevidence: documented120–220k km

Ranked by probability × repair cost, not by how loudly a failure is discussed. Inherited from the engine, gearbox, chassis and shared components, each written once.

Pre-purchase inspection

The same issue records, reordered into the sequence you can actually check them in: cold start, static, drive, paperwork.

7 checks · saved in this browser ·

1Static checksEngine off, ideally on a lift.

Airmatic strut and compressor failureView the car cold and before it's been started, then cycle every ride height and watch all four corners respond. A compressor that runs on after levelling is the early warning.Oil cooler seal leakLook down the back of the engine with a torch for wet oil and fresh cleaning. A suspiciously spotless engine bay on a 200,000 km V6 deserves a question.

2On the driveInclude low-speed manoeuvring, not just an open road.

7G-Tronic conductor plate and 13-pin connector leak (722.9)Test-drive through every gear cold and warm. Scan the transmission, and pull the external 13-pin plug to check for fluid on the pins.

3PaperworkOn these cars the folder is most of the value.

M272 balance shaft gear wear (early petrol V6)walk away without proofTake the engine number and check it against the affected range before you look at anything else, because no amount of service history answers this. A stored camshaft correlation code is the other warning.EGR cooler leakCheck coolant level and look for unexplained top-ups in the service history. Verify the recall was carried out. It's free and searchable by VIN.

4OBD scanMandatory. A seller who refuses a scan has answered the question.

DPF clogging and forced regenerationRead the DPF soot load and the distance since the last regeneration on a scan tool, and check the engine oil level and smell it for diesel. Ask what the car was used for. A short-trip city diesel is the wrong car regardless of mileage.Intake-port shut-off (swirl) actuator failureScan for P2015 and related intake codes; a car that has thrown it before is likely to again unless the oil-leak cause was addressed.

Mileage and servicing

What the odometer does and doesn't tell you here, plus the service items whose neglect causes the expensive failures above.

The OM642 V6 covers enormous distance and it's the surrounding hardware that ages. A high-mileage motorway car with a full record beats a low-mileage one that sat.

Service item	Interval	Cost
Oil cooler seal inspection It's the defining leak on this engine and catching it early saves nothing but confirms the bill.	every 2 years	€0–120 to inspect
Gearbox oil and filter The 7G-Tronic conductor plate and clutches both last longer with fresh oil.	every 80,000 km	€300–450

What to pay

What this engine sells for, against the median of every engine in the chassis. All figures are illustrative placeholders. See the basis chips.

median €9.4k

€5.5k€7.3k€15.3k

Cheapfind the reasonGood buyif it checks outFairnormal moneyOverpricedneeds justifying

Asking price (€)Mileage (km)

Enter an asking price to get a verdict against this variant's band: cheap, fair, good buy or overpriced.

United States vs Europe

1 EUR = 1.08 USD · 2026-07

🇪🇺 Europe · EUR€7,250band €5,500–€15,250

🇺🇸 United StatesNot soldML 320 CDI OM642 was never a US-market car

What that meansNo US band exists to compare. Any car you find there's a private import, parts and specialist knowledge are thinner, and the price says more about import cost than about the market.

US figures are the EU band converted at a stated rate. No US market differential is modelled: we hold no sourced US asking prices, and inventing one would be worse than saying so. What the comparison does show for real is availability. Most of this range was never sold in the US.

ModelMercedes-Benz M-Class ML 320 CDI
ChassisW164
EngineOM642
Years2005–2011
MarketCentral EU
Windowrolling 12 months to 2026-07

Good buy at or under the marker · Median asking price · bar spans the 10th to 90th percentile · dashed line is the w164 median, all 2 engines

Good buy isn't the same as cheapest. Any car without documentation for m272 balance shaft gear wear (early petrol v6) should be priced as if the repair is still owed. Full breakdown by facelift phase →

Buyer notes

Our judgement, kept separate from the records it's built on.

Our read, not a record

This is the same V6 diesel that powers the E-Class and it suits a big SUV even better, since the torque does the work. The oil cooler seals leak on this engine and the labour is what costs, so look for oil in the valley between the banks. Check the air suspension at every height if fitted and listen to the transfer case for whine. So scan the whole car and treat a tired battery as the cause of several unrelated-looking faults.

Everything above this line comes from the issue and specification records. This paragraph is our judgement on top of them. See how we reach it.

Full specification

Manufacturer figures for this engine and body, as recorded in the variant and engine data.

Engine code	OM642 3.0 V6 CDI
Configuration	V6, turbocharged · 2987 cc
Fuel / injection	diesel · common rail
Model years	2005–2011
Facelift phase	Sold either side of the 2008 facelift, 2005–2007 pre, 2008–2011 LCI
Power / torque	224 PS · 510 Nm
Transmissions	7-speed automatic (7G-Tronic)
Gearbox families	Mercedes 7G-Tronic seven-speed automatic (722.9)
Drivetrain	4MATIC
Economy (real-world)	8.5–10.5 l/100 km mixed
Markets	EU