Ml 270 cdi

[NGOK]

Guys

My ML 270 CDI has lost power and will not rev past 3000 revs! On a hill it crawls up with the auto box struggling to find a gear. I have looked on lots of posts and this appears to be a common problem! Any suggestions as to what I can test before I pop in into the garage tomorrow?

Thanks

 

[Audiophile_AU]

Hi NGOK,
it's quite likely the turbocharger isn't functioning. Our ML270 had those symptoms a while ago. It turned out to be quite a subtle fault - the EGR vale wasn't working, because there wasn't enough vacuum boost to help the solenoid close it (turbocharged air goes round in circles - no nett effect). Lack of vacuum was a leaking valve in the brake booster thingy - new brake booster cured it. If you put your head and ears up close to the top of the brake pedal assembly you could hear the hissing of air.
The MB diagnostic stuff can stimulate (command) the EGR valve to open and close - there should be changes in measured vacuum, engine revs etc.
regards from Down Under
David

 

[NGOK]

Hi NGOK,
it's quite likely the turbocharger isn't functioning. Our ML270 had those symptoms a while ago. It turned out to be quite a subtle fault - the EGR vale wasn't working, because there wasn't enough vacuum boost to help the solenoid close it (turbocharged air goes round in circles - no nett effect). Lack of vacuum was a leaking valve in the brake booster thingy - new brake booster cured it. If you put your head and ears up close to the top of the brake pedal assembly you could hear the hissing of air.
The MB diagnostic stuff can stimulate (command) the EGR valve to open and close - there should be changes in measured vacuum, engine revs etc.
regards from Down Under
David

Hi David

Thanks for the feedback. Thankfully Star indicated Mass Air Flow sensor so easy job and she is flying along now. Hopefully that should last for a while now and I can enjoy the drive again.

Many thanks from up yonder.

Gary