W211 E280 CDI engine oil in ECM.
Thread Starter
Newbie
Joined: Oct 2018
Posts: 3
Likes: 0
Mercedes
W211 E280 CDI engine oil in ECM.
Hi All,
First post here and a little case study.
I work as a tech on various makes and models in Western Australia, over the past few days I have had the "pleasure" of working on the above-mentioned vehicle which the customer had recently purchased from a dealer, customer complaint of an oil leak which was apparent from around the oil fill cap and rocker cover area. The engine was degreased and a road test conducted, during the road test it was confirmed that the oil leak was oil being forced from the oil fill cap and another symptom of the engine cutting power during full throttle (like hitting the brakes hard).
On return to the workshop a code scan was conducted, the stored codes were boost control actuator signal interrupted, exhaust back pressure high, EGR valve signal interrupted, O2 sensor short to positive, O2 sensor short to ground, O2 sensor range/performance, O2 sensor heater circuit resistance/range/performance.
Using a manual gauge it was confirmed that crankcase pressure was highly excessive under "snap throttle" conditions, causing oil to be ejected from the oil fill cap. The PIDs also showed that exhaust back pressure was high on snap throttle and boost pressure was highly excessive. A functional test on the turbo boost control actuator was conducted using the scan tool and it was confirmed inoperative.
Wiring schematics were sourced and power and ground to the boost control actuator were confirmed as good, upon removing the connector to the ECM to conduct a continuity test on the boost control signal wire it was discovered that the ECM connector was full of engine oil. The ECM was removed from the vehicle and the housing split and engine oil was also found in the ECM.
At this point the decision was made to try to recover the ECM by cleaning it thoroughly and re-sealing it, cleaning the connectors and terminals and re-testing the components that had thrown codes. Once this was done, the boost control actuator was confirmed as operational, EGR valve was confirmed as operational, the exhaust back pressure was confirmed as within parameters and the crankcase pressure was confirmed as acceptable using a manual gauge.
A test drive on the vehicle confirmed no driveability issues, and the oil leak from the filler cap was also no longer present as a result of normal crankcase pressure.
The source of the engine oil into the engine harness and as a result into the ECM is still to be confirmed, some oil residue is present at the cam position sensors and is possibly wicking from the sensor, through the wiring harness and into the ECM. The O2 sensor has been confirmed as physically damaged (likely due to high exhaust pressure and temperature) and will require replacement.
The repair recommended to the customer is investigation and rectification of the source of the oil leak into the engine harness, replacement of the engine harness and replacement of the O2 sensor.
Yeh ok, a bit of a novel/TLDR, yet, just an insight into the daily routine for an automotive tech and for a customer that thought he had bought a plumb car.
First post here and a little case study.
I work as a tech on various makes and models in Western Australia, over the past few days I have had the "pleasure" of working on the above-mentioned vehicle which the customer had recently purchased from a dealer, customer complaint of an oil leak which was apparent from around the oil fill cap and rocker cover area. The engine was degreased and a road test conducted, during the road test it was confirmed that the oil leak was oil being forced from the oil fill cap and another symptom of the engine cutting power during full throttle (like hitting the brakes hard).
On return to the workshop a code scan was conducted, the stored codes were boost control actuator signal interrupted, exhaust back pressure high, EGR valve signal interrupted, O2 sensor short to positive, O2 sensor short to ground, O2 sensor range/performance, O2 sensor heater circuit resistance/range/performance.
Using a manual gauge it was confirmed that crankcase pressure was highly excessive under "snap throttle" conditions, causing oil to be ejected from the oil fill cap. The PIDs also showed that exhaust back pressure was high on snap throttle and boost pressure was highly excessive. A functional test on the turbo boost control actuator was conducted using the scan tool and it was confirmed inoperative.
Wiring schematics were sourced and power and ground to the boost control actuator were confirmed as good, upon removing the connector to the ECM to conduct a continuity test on the boost control signal wire it was discovered that the ECM connector was full of engine oil. The ECM was removed from the vehicle and the housing split and engine oil was also found in the ECM.
At this point the decision was made to try to recover the ECM by cleaning it thoroughly and re-sealing it, cleaning the connectors and terminals and re-testing the components that had thrown codes. Once this was done, the boost control actuator was confirmed as operational, EGR valve was confirmed as operational, the exhaust back pressure was confirmed as within parameters and the crankcase pressure was confirmed as acceptable using a manual gauge.
A test drive on the vehicle confirmed no driveability issues, and the oil leak from the filler cap was also no longer present as a result of normal crankcase pressure.
The source of the engine oil into the engine harness and as a result into the ECM is still to be confirmed, some oil residue is present at the cam position sensors and is possibly wicking from the sensor, through the wiring harness and into the ECM. The O2 sensor has been confirmed as physically damaged (likely due to high exhaust pressure and temperature) and will require replacement.
The repair recommended to the customer is investigation and rectification of the source of the oil leak into the engine harness, replacement of the engine harness and replacement of the O2 sensor.
Yeh ok, a bit of a novel/TLDR, yet, just an insight into the daily routine for an automotive tech and for a customer that thought he had bought a plumb car.
Super Member
Joined: Apr 2007
Posts: 633
Likes: 48
From: USA
2006 E320 CDI
Hi All,
First post here and a little case study.
I work as a tech on various makes and models in Western Australia, over the past few days I have had the "pleasure" of working on the above-mentioned vehicle which the customer had recently purchased from a dealer, customer complaint of an oil leak which was apparent from around the oil fill cap and rocker cover area. The engine was degreased and a road test conducted, during the road test it was confirmed that the oil leak was oil being forced from the oil fill cap and another symptom of the engine cutting power during full throttle (like hitting the brakes hard).
On return to the workshop a code scan was conducted, the stored codes were boost control actuator signal interrupted, exhaust back pressure high, EGR valve signal interrupted, O2 sensor short to positive, O2 sensor short to ground, O2 sensor range/performance, O2 sensor heater circuit resistance/range/performance.
Using a manual gauge it was confirmed that crankcase pressure was highly excessive under "snap throttle" conditions, causing oil to be ejected from the oil fill cap. The PIDs also showed that exhaust back pressure was high on snap throttle and boost pressure was highly excessive. A functional test on the turbo boost control actuator was conducted using the scan tool and it was confirmed inoperative.
Wiring schematics were sourced and power and ground to the boost control actuator were confirmed as good, upon removing the connector to the ECM to conduct a continuity test on the boost control signal wire it was discovered that the ECM connector was full of engine oil. The ECM was removed from the vehicle and the housing split and engine oil was also found in the ECM.
At this point the decision was made to try to recover the ECM by cleaning it thoroughly and re-sealing it, cleaning the connectors and terminals and re-testing the components that had thrown codes. Once this was done, the boost control actuator was confirmed as operational, EGR valve was confirmed as operational, the exhaust back pressure was confirmed as within parameters and the crankcase pressure was confirmed as acceptable using a manual gauge.
A test drive on the vehicle confirmed no driveability issues, and the oil leak from the filler cap was also no longer present as a result of normal crankcase pressure.
The source of the engine oil into the engine harness and as a result into the ECM is still to be confirmed, some oil residue is present at the cam position sensors and is possibly wicking from the sensor, through the wiring harness and into the ECM. The O2 sensor has been confirmed as physically damaged (likely due to high exhaust pressure and temperature) and will require replacement.
The repair recommended to the customer is investigation and rectification of the source of the oil leak into the engine harness, replacement of the engine harness and replacement of the O2 sensor.
Yeh ok, a bit of a novel/TLDR, yet, just an insight into the daily routine for an automotive tech and for a customer that thought he had bought a plumb car.
First post here and a little case study.
I work as a tech on various makes and models in Western Australia, over the past few days I have had the "pleasure" of working on the above-mentioned vehicle which the customer had recently purchased from a dealer, customer complaint of an oil leak which was apparent from around the oil fill cap and rocker cover area. The engine was degreased and a road test conducted, during the road test it was confirmed that the oil leak was oil being forced from the oil fill cap and another symptom of the engine cutting power during full throttle (like hitting the brakes hard).
On return to the workshop a code scan was conducted, the stored codes were boost control actuator signal interrupted, exhaust back pressure high, EGR valve signal interrupted, O2 sensor short to positive, O2 sensor short to ground, O2 sensor range/performance, O2 sensor heater circuit resistance/range/performance.
Using a manual gauge it was confirmed that crankcase pressure was highly excessive under "snap throttle" conditions, causing oil to be ejected from the oil fill cap. The PIDs also showed that exhaust back pressure was high on snap throttle and boost pressure was highly excessive. A functional test on the turbo boost control actuator was conducted using the scan tool and it was confirmed inoperative.
Wiring schematics were sourced and power and ground to the boost control actuator were confirmed as good, upon removing the connector to the ECM to conduct a continuity test on the boost control signal wire it was discovered that the ECM connector was full of engine oil. The ECM was removed from the vehicle and the housing split and engine oil was also found in the ECM.
At this point the decision was made to try to recover the ECM by cleaning it thoroughly and re-sealing it, cleaning the connectors and terminals and re-testing the components that had thrown codes. Once this was done, the boost control actuator was confirmed as operational, EGR valve was confirmed as operational, the exhaust back pressure was confirmed as within parameters and the crankcase pressure was confirmed as acceptable using a manual gauge.
A test drive on the vehicle confirmed no driveability issues, and the oil leak from the filler cap was also no longer present as a result of normal crankcase pressure.
The source of the engine oil into the engine harness and as a result into the ECM is still to be confirmed, some oil residue is present at the cam position sensors and is possibly wicking from the sensor, through the wiring harness and into the ECM. The O2 sensor has been confirmed as physically damaged (likely due to high exhaust pressure and temperature) and will require replacement.
The repair recommended to the customer is investigation and rectification of the source of the oil leak into the engine harness, replacement of the engine harness and replacement of the O2 sensor.
Yeh ok, a bit of a novel/TLDR, yet, just an insight into the daily routine for an automotive tech and for a customer that thought he had bought a plumb car.
Senior Member
Joined: Aug 2014
Posts: 337
Likes: 20
From: Charlotte, NC
2005 E320 CDI, 2015 GLA 250
How bizarre. I did have something like this happen once where oil got into a speedometer cable and the internal spring cable screwed (pumped) the oil up the cable and into the speedometer. Is there a mechanical speedometer cable involved?
Regards,
Peter
Regards,
Peter
Thread Starter
Newbie
Joined: Oct 2018
Posts: 3
Likes: 0
Mercedes
Hi again,
After a bit of investigation, an oil leak through the oil temperature sensor and into the wiring harness was found, the oil was wicking through the temperature sensor wires and being deposited into the main ECU connector and thus the ECU. The sensor was replaced and terminals and ECU cleaned again and the customer has made the decision to sell the vehicle without any further repairs.
After a bit of investigation, an oil leak through the oil temperature sensor and into the wiring harness was found, the oil was wicking through the temperature sensor wires and being deposited into the main ECU connector and thus the ECU. The sensor was replaced and terminals and ECU cleaned again and the customer has made the decision to sell the vehicle without any further repairs.
Thread Starter
Newbie
Joined: Oct 2018
Posts: 3
Likes: 0
Mercedes
The wires are externally sealed at the sensor and ECU with "weatherpack" type silicon rubber terminal seals to prevent external water ingress etc, the problem was found to be oil temperature sensor wires wicking oil internally from a faulty engine oil temperature sensor.
