Toadshall
New Member
All,
I am a new member to the site. I am early retired, own a C200K purchased new in 2001 and I like to keep my wheels for a long time. The car is maintained re specific problems (albeit reluctantly) by an MB (workshop facility only) main agent. I have an engineering background, and after private research, quiz their senior group roving technician in detail re problems.
Engine 111955 series, Partial load ventilation nozzle blockage.
This appears to be a well known and understood problem. These nozzles ventilate the lower crankcase at partial loads avoiding crankcase compression. They form part of the closed circuit emissions system.
Two nozzles are located at the inlet port entrance of the cylinder head and if they block oil is carried over by the supercharger into the air inlet tract. Oil collects in the intercooler and is eventually transmitted onto the Air mass meter/Air temperature unit. This causes the illumination of the engine management light on the dash. MB replace the air mass meter, though it may be recoverable, and clean thoroughly all components in the inlet tract. The expensive bit is replacing the nozzles as the inlet manifold/ injection gear need to be removed as a unit to gain access
MB suggest that if fully synthetic oil is used the problem will not re-occur. The logic behind their viewpoint is that the varnishes and resins in the mineral component of a semi synthetic product causes the nozzles to block. Fully synthetic oils such as Mobil 1 are inherently stable, hold there original specifcation in extreme conditions for a huge period and do not emit the resins, varnishes and other by products that mineral oils do.
A word of caution. Changing from a semi to a fully synthetic oil product after a prolonged period of semi usage may exaggerate the problem as a fully synthetic oil is very searching and will put existing engine residues into suspension. From new I used Castrols Magnatec semi. I changed to Mobil 1 0W 40 with 8K milage intervals two oil changes ago. I had nozzle blockage at the end of the second period. My car is nine years old and has completed 88K miles.
111955 engine series, Head gasket failure.
We all know head gaskets fail, but at 88.8K miles I was taken aback. My gut feeling is that a high engine bmep does not help, but I also believe that poor "head structure" contributes to the problem. These engines were originally introduced with much lower bmep's and no supercharging. I noticed that all was not well when changing the oil, as I could see a blue line accross the bottom front of the auto transmission from above. This of course was a coolant leak from the rear nearside of the engine. Gasket failure at around 100K seems to be commonplace for the 111 higher output engines, but much less so for its 271 engine replacement.
Throttle body
Its been an uncomfortable and expensive time. I was alarmed when the engine management light illuminated again two days before a precise check re the blue discolouration on the auto transmission and at 88.8K miles. Failure of the throttle body was diagnosed after a day of careful measurements and an albeit brief recovery. The symptoms were a brief hunting of the engine at start up that died away within a minute or so. I have yet to quiz the agents technical man which I plan to do later this week. The body is humungously expensive. It seems that irregular engine tick over may often be related to the throttle body. I was always happy with a throttle cable - servo's are a reliability nightmare when they get older.
Myself and my wife drive this car relatively gently - though sometimes, I know that can exaggerate prob's.
Regards,
Toadshall
I am a new member to the site. I am early retired, own a C200K purchased new in 2001 and I like to keep my wheels for a long time. The car is maintained re specific problems (albeit reluctantly) by an MB (workshop facility only) main agent. I have an engineering background, and after private research, quiz their senior group roving technician in detail re problems.
Engine 111955 series, Partial load ventilation nozzle blockage.
This appears to be a well known and understood problem. These nozzles ventilate the lower crankcase at partial loads avoiding crankcase compression. They form part of the closed circuit emissions system.
Two nozzles are located at the inlet port entrance of the cylinder head and if they block oil is carried over by the supercharger into the air inlet tract. Oil collects in the intercooler and is eventually transmitted onto the Air mass meter/Air temperature unit. This causes the illumination of the engine management light on the dash. MB replace the air mass meter, though it may be recoverable, and clean thoroughly all components in the inlet tract. The expensive bit is replacing the nozzles as the inlet manifold/ injection gear need to be removed as a unit to gain access
MB suggest that if fully synthetic oil is used the problem will not re-occur. The logic behind their viewpoint is that the varnishes and resins in the mineral component of a semi synthetic product causes the nozzles to block. Fully synthetic oils such as Mobil 1 are inherently stable, hold there original specifcation in extreme conditions for a huge period and do not emit the resins, varnishes and other by products that mineral oils do.
A word of caution. Changing from a semi to a fully synthetic oil product after a prolonged period of semi usage may exaggerate the problem as a fully synthetic oil is very searching and will put existing engine residues into suspension. From new I used Castrols Magnatec semi. I changed to Mobil 1 0W 40 with 8K milage intervals two oil changes ago. I had nozzle blockage at the end of the second period. My car is nine years old and has completed 88K miles.
111955 engine series, Head gasket failure.
We all know head gaskets fail, but at 88.8K miles I was taken aback. My gut feeling is that a high engine bmep does not help, but I also believe that poor "head structure" contributes to the problem. These engines were originally introduced with much lower bmep's and no supercharging. I noticed that all was not well when changing the oil, as I could see a blue line accross the bottom front of the auto transmission from above. This of course was a coolant leak from the rear nearside of the engine. Gasket failure at around 100K seems to be commonplace for the 111 higher output engines, but much less so for its 271 engine replacement.
Throttle body
Its been an uncomfortable and expensive time. I was alarmed when the engine management light illuminated again two days before a precise check re the blue discolouration on the auto transmission and at 88.8K miles. Failure of the throttle body was diagnosed after a day of careful measurements and an albeit brief recovery. The symptoms were a brief hunting of the engine at start up that died away within a minute or so. I have yet to quiz the agents technical man which I plan to do later this week. The body is humungously expensive. It seems that irregular engine tick over may often be related to the throttle body. I was always happy with a throttle cable - servo's are a reliability nightmare when they get older.
Myself and my wife drive this car relatively gently - though sometimes, I know that can exaggerate prob's.
Regards,
Toadshall
