I have recently aquired a 1985 Mercedes 300D that was purchased new by my mother . The car has always been maintained and is in pretty good shape with135,00 miles. My question is ,at 65mph what rpm should this engine be turning? At present ,the engine turns about 27-2800rpm, is this too high? Also ,I have a very steep driveway, the car will back up the drive fine, but will not go up the drive in either drive or low gear. Is this normal or what? Any ideas or suggestions are greatly apprieciated, Jim B.

 

The RPM is correct. The driveway issue is another story. Will it climb the hill at operating temperature? Is the trans slipping, or will it just not achieve enough RPM's to go?

 

Hi

I just want to know is my car rpm right. Its is a 1984 300SD, at 70 MPH the rpm reads 3300 RPM,but with my 83 SD it reads 3000 RPM @ 70. So which is wrong the 1983 SD or 1984 SD. And Grabiral if you trying to get up the hill try doing this, first set your gear to low, then press your acclarator 1/4 or 1/2 way down and the same time press your brakes too (not hand brake), and keep your leg on the gas paddle and let go off the brakes. It works for my 77 300D.

THX

 

My 85 SD is right on 3000 RPM at 70 MPH. So I'm not sure, but 3300 @ 70MPH sounds high too me.

 

Hi

Maybe the RPM guage needs be calibrated.

Thx

 

Answer to Mr. 47.... I'm not sure if the Tach can be calabrated. The pick up on the front of the crank is fixed, it counts each revolution. It's possible the tach is not reading out the number of RPM's. My guess for the RPM variation between our respective cars at speed has to do with tire sizes and/or tire wear, or inaccurate speedometer. Also, I wonder if MB changed the rear gear ratio at all between models for the years 1980-1985? Interesting....

I know my old 240D sounds like it's screaming at 70 MPH.