740 engine RPM at 70 MPH
 

Good Morning, I have a 1988 740 GLE sedan with the 4 cylinder (non Turbo). At 70 mph the tach is showing about 4200. THE OD SOLENOID IS OPERATING PPOPERLY AT ALL TIMES. I drove my mechanic's personal 740( non turbo) wagon and his RPM was much lower at 70 (maybe 2750) than what my 740 indicated. He thinks the tach is broken So does 4200 RPM at 70 MPH appear inaccurate and what part would I likely replace? BTW, my gas mileage is about 22 mpg on the highway at 70 mph. I read that some 740 (non turbo) owners are getting middle upper 20's on the highway, and as much as 28 MPG. Hmmm! Thanks guys, this is my first post and I don't even know where to look for your responses. have a great 4th of July weekend :) Mark B

This is the wrong section for this question--should be in the 240, 740, 940...

Still, yes, RPM way high, should be 2,800 at 70 mph. Are you sure your Overdrive is working? Do you get a shift from 3rd gear into the OD? Does the engine sound labored? The tach could be faulty, wouldn't be the first time...