Carsieve At a glance
- What it is: the Mercedes 2.1 four-cylinder common-rail diesel, 2008-2021. Found in the C-Class, E-Class, GLK, GLC, A, B, CLA, GLA and in Sprinter, Vito and V-Class vans. The newer OM654 2.0 diesel is a different engine.
- Main faults: the timing chain (the chain that drives the camshafts) stretches and rattles on cold start. Early injectors on the 220 and 250 CDI fail. Engines built in 2014 can leak oil at the chain tensioner seal.
- Reliability: 2/5. Well maintained engines often pass 300,000 km, but the chain and injector faults are common.
- DIY: 1/5. The chain and tensioner work is shop work. The 2014 seal fix takes 1.5-2.5 workshop hours.
- Prefer: a 200 CDI, which the sources say was not affected by the injector fault. A car with a chain check and oil change records.
- Avoid: a rattle on cold start, a falling coolant level, and a car with no proof that the 2014 seal fix or the emissions software update was done.
Known issues
| Issue | Affects | Typical km | Repair cost |
|---|---|---|---|
| Timing chain stretch and cold start rattle | All OM651 | From about 150,000 km | Chain job not stated. Engine damage: mid to high four-digit EUR (Germany, year not stated) |
| Delphi piezo injector failures | 220 and 250 CDI with piezo injectors. 200 CDI not affected | About 50,000-150,000 km | 400-800 EUR per injector (Germany, year not stated) |
| Oil leak at the chain tensioner seal | Engines built February to November 2014 | Not stated | Not stated. Workshop time 1.5-2.5 hours |
| Coolant leak at the cylinder head connection | Some 200, 220 and 250 CDI | Not stated | Not stated |
Before you buy
- Timing chain (scanner needed). Start the engine cold and listen for a metallic rattle for 1-3 seconds. Ask a Mercedes dealer or a diesel specialist to read the cam phase offset (the timing gap between camshaft and crankshaft) with XENTRY, the Mercedes diagnostic tool. Check for codes P0016 and P0017. A plain OBD2 scanner may miss the offset. Bad: a rattle, a stored P0016 or P0017, or a large offset. A jumped chain can destroy the engine.
- Injectors (scanner needed). Check for a warning light, rough running, judder and higher fuel use. Read the fault codes. Ask for the injector type and any replacement or service action invoice. Bad: a fault code, or piezo injectors with no service record.
- Coolant (no scanner). Check the coolant level when the engine is cold, and check it again after a few weeks. Ask a dealer whether service action 1204P59A93 was done on the cylinder head coolant connection. Bad: a falling level or no record of the work.
- Tensioner seal recall (VIN check). For cars built February to November 2014, ask a Mercedes dealer to check the VIN for the seal ring fix. Bad: no record of the fix.
- Emissions software update (VIN check). Ask a Mercedes dealer to check the VIN for the emissions software update. Bad: no record of the update.
- Oil and service history (no scanner). Ask for oil change records. Long gaps between oil changes, short trips and poor oil all speed up chain wear. Bad: long gaps or no records.
Models with this engine
| Brand | Model | Generation | Production years | Power | Engine codes | ADAC versions |
|---|---|---|---|---|---|---|
| Jeep | Compass | PK facelift | 2011–2015 | 136–163 PS (100–120 kW) | 651 925 | 6 |
| Mercedes-Benz | A-Klasse | 176 | 2012–2015 | 109–170 PS (80–125 kW) | 651901, 651930 | 37 |
| Mercedes-Benz | A-Klasse | 176 facelift | 2015–2018 | 136–177 PS (100–130 kW) | 651930 | 40 |
| Mercedes-Benz | B-Klasse | 246 | 2011–2014 | 109–170 PS (80–125 kW) | 651901, 651930 | 7 |
| Mercedes-Benz | B-Klasse | 246/242 facelift | 2014–2018 | 136–177 PS (100–130 kW) | 651930 | 97 |
| Mercedes-Benz | C-Klasse | 204 | 2007–2011 | 136–204 PS (100–150 kW) | 651911, 651912, 651913 | 97 |
| Mercedes-Benz | C-Klasse | 204 facelift | 2011–2015 | 120–204 PS (88–150 kW) | 651911, 651912, 651913 | 125 |
| Mercedes-Benz | C-Klasse | 205 | 2014–2018 | 136–231 PS (100–170 kW) | 651921 | 201 |
| Mercedes-Benz | CLA | 117 | 2013–2016 | 136–177 PS (100–130 kW) | 651901, 651930 | 60 |
| Mercedes-Benz | CLA | 117 facelift | 2016–2019 | 136–177 PS (100–130 kW) | 651930 | 106 |
| Mercedes-Benz | CLS | 218 | 2010–2014 | 204 PS (150 kW) | 651924 | 4 |
| Mercedes-Benz | CLS | 218 facelift | 2014–2017 | 170–204 PS (125–150 kW) | 651924 | 18 |
| Mercedes-Benz | E-Klasse | 207/212 | 2009–2013 | 136–231 PS (100–170 kW) | 651911, 651924, 651925 | 126 |
| Mercedes-Benz | E-Klasse | 207/212 facelift | 2013–2017 | 136–231 PS (100–170 kW) | 651911, 651924, 651925 | 158 |
| Mercedes-Benz | GLA | 156 | 2014–2017 | 136–177 PS (100–130 kW) | 651930 | 55 |
| Mercedes-Benz | GLA | 156 facelift | 2017–2019 | 136–177 PS (100–130 kW) | 651930 | 60 |
| Mercedes-Benz | GLA | 247 | 2020–2023 | 150–190 PS (110–140 kW) | 651930 | 20 |
| Mercedes-Benz | GLC | 253 | 2015–2019 | 170–204 PS (125–150 kW) | 651921 | 12 |
| Mercedes-Benz | GLE | 166/292 | 2015–2018 | 204 PS (150 kW) | 651960 | 2 |
| Mercedes-Benz | GLK-Klasse | 204 | 2008–2012 | 143–204 PS (105–150 kW) | 651912, 651916 | 16 |
| Mercedes-Benz | GLK-Klasse | 204 facelift | 2012–2015 | 143–204 PS (105–150 kW) | 651912, 651916 | 7 |
| Mercedes-Benz | M-Klasse | 166 | 2011–2015 | 204 PS (150 kW) | 651960 | 2 |
| Mercedes-Benz | S-Klasse | 221 facelift | 2011–2013 | 204 PS (150 kW) | 651961 | 2 |
| Mercedes-Benz | S-Klasse | 217/222 | 2014–2017 | 231 PS (170 kW) | 651921 | 8 |
| Mercedes-Benz | SLK-Klasse | 172 | 2011–2016 | 204 PS (150 kW) | 651980 | 3 |
| Mercedes-Benz | Sprinter | 906 | 2011–2013 | 129–163 PS (95–120 kW) | 651.955, 651.957 | 36 |
| Mercedes-Benz | Sprinter | 906 facelift | 2013–2018 | 114–163 PS (84–120 kW) | 651.955, 651.957 | 174 |
| Mercedes-Benz | Sprinter | 907/910 | 2018–2021 | 114–163 PS (84–120 kW) | 651, 651.955, 651.957 | 210 |
| Mercedes-Benz | V-Klasse | 447 | 2014–2019 | 136–190 PS (100–140 kW) | 651.950 | 325 |
| Mercedes-Benz | Viano | 639 facelift | 2010–2014 | 136–163 PS (100–120 kW) | 651.940 | 72 |
| Mercedes-Benz | Vito | 639 facelift | 2010–2014 | 95–163 PS (70–120 kW) | 651.940 | 71 |
| Mercedes-Benz | Vito | 447 | 2014–2019 | 136–190 PS (100–140 kW) | 651.950 | 186 |
In detail
Timing chain stretch and cold start rattle
The timing chain drives the camshafts. A hydraulic tensioner keeps it tight. The chain is a single-row (simplex) roller chain.
Symptoms. A metallic rattle for 1-3 seconds after a cold start. Later the rattle can stay. Power loss or limp mode can follow if the cam timing is far out.
Cause. The chain stretches. The sprocket wears. The tensioner weakens. A leaking check valve in the tensioner can let the chain sag overnight. Early builds had a weaker sprocket and tensioner. The chain sits at the output side of the engine, so the job is laborious and expensive.
Which cars. All OM651 engines. The faults start from about 150,000 km. There is no fixed limit. Short trips, long oil intervals and poor oil speed up the wear.
Fix. Early stage: replace the tensioner with the reinforced version. Advanced stage: replace the full set (chain, sprocket, tensioner and guide rails) with the pull-through method, which does not need the engine or gearbox out. After the repair, check the cam phase offset and make sure the fault memory stays empty after several starts.
Revised parts. A reinforced tensioner. No part numbers are given in the sources.
Cost. Germany, year not stated: engine damage from a jumped chain is in the mid to high four-digit EUR range. The price of the chain job is not stated.
Sources: kfz-dietrich, OM651 chain rattle, mbpassion, OM651 weak points, gebrauchtwagenberater, OM651 problems, Autoscore, OM651 reliability
Delphi piezo injector failures
The injector sprays fuel into the cylinder. Early 220 and 250 CDI cars used piezo injectors from Delphi. The 200 CDI used magnetic injectors and is not affected.
Symptoms. A warning light and limp-home mode. Judder, rough running and vibration when accelerating. Higher fuel use and worse exhaust readings.
Cause. Mercedes named production faults in the Delphi piezo injectors in 2009. The press reported that Mercedes acknowledged 2,800 cases in Germany.
Which cars. The 220 and 250 CDI with piezo injectors. The 200 CDI is not affected. Sources disagree on when the 220 CDI changed to magnetic injectors. The dates given are 2010, spring 2011 and mid-2012. The 250 CDI kept piezo injectors to the end of the series in some sources. The change date is disputed. Check the injector type by VIN.
Fix. Mercedes ran a customer service action. It replaced the Delphi injectors with magnetic (solenoid) injectors, and fitted a new engine control unit (ECU), a new fuel return line and a new engine cover.
Revised parts. Magnetic (solenoid) injectors, new ECU, new fuel return line. No part numbers are given.
Cost. Germany, year not stated: 400-800 EUR per injector.
Sources: AUTO BILD, diesel problems in E-Class and C-Class (2009), Australian Car Reviews, OM651 engine, auto.ru, Mercedes-Benz GLK faults, kfz-dietrich, diesel injector faults and costs
Oil leak at the chain tensioner seal
The chain tensioner has a sealing ring. The ring can leak oil. The hydraulic tensioner then runs short of oil, and the chain may jump.
Symptoms. Small amounts of oil leak from the tensioner area. The chain may jump, which can destroy the engine.
Cause. Tolerances in the sealing ring. Engines built February to November 2014 are named, and replacement engines may also be affected.
Which cars. Engines built between February and November 2014 in Germany. Vito and Sprinter vans built in the same period were named in the 2015 German press. Mercedes could not give the exact series.
Fix. Replace the sealing ring on the chain tensioner. Workshop time is 1.5-2.5 hours.
Revised parts. A revised sealing ring. No part number is given.
Cost. Price not stated. The workshop time is 1.5-2.5 hours.
Sources: mbpassion, OM651 seal ring (2015), Eurotransport, Sprinter and Vito recall (2015), Australian Car Reviews, OM651 recall records
Coolant leak at the cylinder head connection
The cylinder head has a coolant connection that can leak on some models.
Symptoms. A falling coolant level.
Cause. The coolant connection stub on the cylinder head.
Which cars. Some 200, 220 and 250 CDI. The build years are not stated.
Fix. A service action (number 1204P59A93) replaces the coolant connection stub on the cylinder head. Mercedes did not send out a proactive notice. Ask a dealer whether it was done.
Revised parts. A new coolant connection stub. No part number is given.
Cost. Not stated.
Sources: mbpassion, OM651 weak points, gebrauchtwagenberater, OM651 problems, Autoscore, OM651 reliability
Recalls
| Country | Code | Years or build range | What is done |
|---|---|---|---|
| Germany | not given | Built February to November 2014 | Sealing ring on the chain tensioner replaced |
| Australia | PRA 2015/14509 | Available for sale during 2014 | Oil seal ring on the chain tensioner may leak. Fix not given |
| Germany | not given | Years not given | Software update. Authorities found an illegal defeat device in the emissions control |
| Germany | 1204P59A93 (service action) | Some 200, 220 and 250 CDI, years not given | Coolant connection stub on the cylinder head replaced |
| Australia | PRA 2010/12193 | Built 1 November 2009 to 1 November 2010 | Fuel filter leak. Fix not given |
Check open campaigns by VIN with a Mercedes dealer before you buy.
Maintenance
- Oil. Change the oil on time with the oil approval in the service book. Long intervals, short trips and poor oil speed up chain wear.
- Coolant. Check the coolant level often. A falling level is an early sign of the cylinder head coolant leak.
- Chain. A cold start rattle means the chain needs an inspection, not only a new tensioner.
- Longevity. Well maintained engines often pass 300,000 km.
Sources
English
- Australian Car Reviews, OM651 engine
- Australian Car Reviews, OM651 recall records
- Autoscore, OM651 reliability
German
- AUTO BILD, diesel problems in E-Class and C-Class (2009)
- mbpassion, OM651 weak points
- mbpassion, OM651 seal ring (2015)
- Eurotransport, Sprinter and Vito recall (2015)
- gebrauchtwagenberater, OM651 problems
- kfz-dietrich, OM651 chain rattle
- kfz-dietrich, diesel injector faults and costs