I'm on a road trip in Oregon and Washington. Today I was driving 80 MPH at 3800 RPM. The RPM seems high for that speed. Can anyone with a similar car let me know what their car does?

It would be nice to know the RPMs at 60, 70, and 80 mph for these 300SDs.

Thanks!

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1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI

Hmm. That sounds like you are in third...

80 mph should be around 3200

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Rear ratio should be 3.07:1
Top gear transmission is 1:1
Tires are around 195-75R14 (put tire size here) use ratio calculator on the web. Figure 200 rpm higher than it comes up with to account for TC slippage

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I found you should be around 3400 at 80 - standard rear end, stock tires, auto trans.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

The fuel injection pump timing on my car is retarded. Going 80 mph is almost maxed out. It did get 24.9 mpg today, mostly at 65-70 mph. Going 80 mph it was getting about 22 mpg, but that was mixed 50% with in town driving before the road trip.

I'm thinking of stopping in at Oregon Fuel Injection in Eugene, Oregon. They want the car for a day and a half to remove the IP, test & adjust it, then reinstall and adjust the timing. Estimated cost $750 to $1000, plus hotel nights. OUCH.

__________________
.
1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI

According to the tachometer, my car does 5000rpm @ 75mph in 4th gear, with a standard (manual) transmission. That being said, I don't think I've ever seen two tachometers show the same rpm at any given speed in these cars

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1982 300D Turbodiesel, daily driver. Mods so far: Fram 8038 paper filter, 4 brake light mod, Gen II w126 (front) rotors/calipers, boost turned up to 12lbs, non-egr manifolds, water/methanol injection, 4-speed manual
1980 300SD Turbodiesel, project car, nearly ready to hit the street

1974 240D, New paint

3800 at 80mph in a 3.07 with stock wheels sounds pretty close, the tach might be off a bit. I usually run around 3400 at 75mph in our '82 300SD's.

My 420sel with a 2.47 diff is about 2950rpm at 80....so 3700ish is about right for a 3.07.

The 85's have a 2.88 differential which does drop a few hundred rpm off and helps a bit.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Mine likes to show 6000 rpm at idle. Or 0. Or anything in between.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I have been running about 3000 RPM at roughly 65 MPH

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

3800 at 80 sounds about right to me with the 307 or 288 diff...not a lot of difference there. I think my 350 SDL was around 3700 at 80 so with a 307 3800 sounds about right.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I stopped in Oregon Fuel Injection in Eugene, Oregon. It was just going to take too long and cost too much.

The car is running ok at speed. At 70 mph it was going at 3550 rpm. I'll adjust the IP timing when I get home. Today it got 25.25 mpg.

__________________
.
1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI

Been running 2900rpm for 65mph, 3200-3300for 72mph.
Ran 90mph at just under 4000 for 20miles ( running late for work)
All with 3.07 and 205x14 bundts tires/wheels. All correct with gps

84 300SD, 162k. Average honest mpg 28-30, respectively

3,000 RPM @ 70 mph - 83 300SD

Same here 1983 300SD 3000rpm @70mph