1985 300D Turbodeisel cruise rpm
 

What is the normal rpm my 300D turbo(auto trans) should be turning at 65mph? Mine turns about 2800, is this normal? Thanks ,Jim

That is a normal rpm at that speed. Remember.....that year was when the 55mph limit was nationwide.

(I also remember certain socialist politicians, at that time, came to Texas and were aghast when they realized that most folks around here just ignored it.;) )

Agreed, good rpm for 65.

Yeah on the 85 with the lower diff gears...2800 rpm is normal for 60 mph with the higher, pre 1985 gears...

Yes, its fine.

Let off the pedal at 65 mph to see how much slip there is in the torque converter. There should be ~ 6% at 65 mph in average conditions. Tach, if accurate, should drop to ~2625 rpm @ 65 mph assuming wheels are equipped with stock rubber (195/65/R14's).

Most american cars of that era aren't really safe/capable of over 55 though... :D :D ;)

Sounds about right......
 

I generally run a bit over that 70-75 mph on the Interstate.....just a tad over 3,000 rpm....:D Locally with these winding hilly roads in WV, I never get a long run at speeds around 65 mph.....

SB

Also of Note: According to the book MB book Technical Data Passenger Cars, April 1985 edition.....an '85 300D should get its best fuel mileage at 120 km/h or 75 mph.......

im running 70 mph @ 3000 rpm, so you seem to be right on the money.
shorebilly, where did u read that? if thats true, then im gona have to start speeding again

Official MB Publication....
 

The li'l grey book, Mercedes-Benz Technical Data Passenger Cars, page #47....Chapter 00, General Technical Data, Fuel and Engine Oil Consumption...

There are no entries for W123.133 (USA, Turbodiesel) but the figures for W123.130 and W123.193 TD Turbo are similar......

SB

Also of Note: Engine Oil Consumption, max. 1.5L/1000km

Almost exactly 3000 rpm for me is 70 mph and about 2800rpm is about 65. Mine is an 85 300SD so it should be almost identical (mines a cali car other wise it would be identical).

That seems to confirm what I have noticed. Mine might do a little better at a higher speed because I modified the turbo with a 50 trim compressor wheel.

Seems a little high compared to mine. I also have an '85 model, and at 65mph I am running exactly 0 rpm..........:( :(

jimmy did you know your tach is broke?????

Mine to! I still can't figure out how I only get 20 something MPG with the engine not turning. :confused: :D

After today's trip my mileage will be suffering though. After a 2 hour drive I only covered 0 miles according to my odometer. :rolleyes: