vinkodex.OM651 2.1/2.2 diesel: Delphi piezo injectors and rear timing chain
Typically between 50,000 and 250,000 km. It does not show up on every car.
expensive
severity
between 50,000 and 250,000 km
mileage
1
sources
1 source next to the write-up.
The fault
How you spot it
The Mercedes OM651 common rail diesel has two faults that are independent of each other.
1) Delphi piezo injectors. According to the German technical press the fault affected the two more powerful versions (125 kW / 170 hp and 150 kW / 204 hp). The weaker versions got solenoid injectors and were not affected. The fault could show up as early as around 50,000 km: the engine drops into limp mode, power is limited, and the car can still be driven slowly. Because of supply shortages the maker at first replaced only the failed injector rather than all four, so some owners went back four times. Later they moved to replacing the full set. From spring 2011 every 220 CDI version got solenoid injectors; the 250 CDI kept piezo injectors throughout, in several revised versions.
2) Timing chain. The engine runs on gears plus a short simplex roller chain. Increased chain wear (typically caused by a faulty chain tensioner) shows up occasionally at higher mileage. The replacement is very labour intensive, because the chain sits on the rear of the engine, on the gearbox side. The labour is the bigger part of the bill.
In November 2014 the chain tensioner caused trouble again: it can release, and engine oil can leak. The maker recalled cars built between February and November 2014. If the car falls in that window, check that the campaign was carried out.
The water pump can leak too.
Which model
Who it affects
The card opens the generation, the engine or the transmission.
Engines and transmissions
Engine
OM651DE22LA
Engine
OM651DE18LA
vinkodex.Checklist
OM651 2.1/2.2 diesel: Delphi piezo injectors and rear timing chain
What you would check for this fault. Take it to the car.
Before you buy
Checklist
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Sources
How we know
Information, not an expert opinion
We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.
- A fault on the list does not mean the car you are looking at has it.
- A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
- You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.