A6420700587 — Technical Research
Bosch piezo common-rail injector for the Mercedes-Benz OM642 3.0 V6 CDI engine. Mercedes OE A6420700587; Bosch numbers 0445115027 / 0445115064. Notorious for injector-seal 'black death'. Coding required after fitting. Key symptoms: Hard starting and poor cold running; Rough idle / misfire; Black carbon ('black death') around an injector base; Smoke, rough acceleration and loss of drivability. Common failure modes: Injector-seal blow-by ('black death'); Piezo stack degradation; Excessive back-leakage.
Bosch A6420700587 (0445115027) Mercedes OM642 3.0 V6 CDI Piezo Injector
Bosch piezo common-rail injector for the Mercedes-Benz OM642 3.0 V6 CDI engine. Mercedes OE A6420700587; Bosch numbers 0445115027 / 0445115064. Notorious for injector-seal 'black death'. Coding required after fitting. Key symptoms: Hard starting and poor cold running; Rough idle / misfire; Black carbon ('black death') around an injector base; Smoke, rough acceleration and loss of drivability. Common failure modes: Injector-seal blow-by ('black death'); Piezo stack degradation; Excessive back-leakage.
Worn piezo injectors with high back-leakage drop cranking rail pressure.
An out-of-balance injector under/over-fuels a cylinder.
A failed seal lets combustion gas escape and carbonise around the injector bore.
Worn nozzle/needle degrades metering.
Over-fuelling or leakage wastes fuel.
Combustion blow-by past a failed copper seal.
- WarningOM642 injectors are prone to seizing in the head from 'black death' carbon. Use a proper puller and expect difficult extraction on neglected engines.
- InstallationAlways fit a new copper seal and hold-down bolt, clean the bore/threads, and use the correct torque-and-angle procedure to prevent blow-by.
- InstallationAfter replacement, programme injector quantity/coding into the CDI control unit with Mercedes diagnostics.
- TestingRequires a Bosch piezo-capable common-rail bench; standard solenoid-only benches cannot test these.
What is Bosch A6420700587?+
It is the Mercedes OE reference for a Bosch piezo common-rail injector on the OM642 3.0 V6 CDI engine; the Bosch numbers are 0445115027 and 0445115064.
Which vehicles use this injector?+
OM642-engined Mercedes C/E/S-Class, ML/GL, Sprinter and Viano, plus Chrysler 300C 3.0 CRD and Jeep Grand Cherokee/Commander 3.0 CRD.
Is it a piezo or solenoid injector?+
It is a piezoelectric injector and needs a Bosch piezo-capable test bench.
What is 'black death' on the OM642?+
Hard black carbon build-up around the injector base caused by combustion gases leaking past a failed copper seal; it can seize the injector in the head.
What are the Bosch numbers for A6420700587?+
0445115027 and 0445115064 (0445115063 is a related alternate).
Do I need to code the injector after fitting?+
Yes - injector quantity/coding must be programmed into the CDI control unit with Mercedes diagnostics.
What are the symptoms of a failing OM642 injector?+
Hard starting, rough idle/misfire, smoke, loss of power, higher fuel use and black carbon around the injector base.
Why is my injector seized in the head?+
Years of 'black death' carbon lock it into the bore. Use a dedicated puller; do not lever against the head.
Why renew the copper seal and hold-down bolt?+
Both are one-use items; reusing them risks blow-by and the carbon build-up that damages the injector and head.
Should I change one or all six?+
Diagnose each with live correction values and a bench test; on high-mileage OM642 engines it is common to renew a full set.
Can a leaking injector damage the engine?+
Yes - persistent blow-by and soot contamination can damage the bore and contribute to wider running problems.
Does a remanufactured A6420700587 perform like new?+
A properly remanufactured piezo injector is bench-tested and recalibrated to the Bosch plan to meet original delivery and back-leakage specs.