The speedometer in my '85 300D is way off. My actual speed (checked with GPS) is 50% higher than the speed indicated (reads 40 actually 60, reads 50 actually 75, etc.) My odometer and tripometer work perfectly as checked with both GPS and mile marker signs; literally less than a tenth of a mile off for over 30 miles... The speedo needle moves normally and returns to zero when stopped. This one is beyond me, I thought the speedomoter was mechanical. Does the amplifier on the back effect indicated speed?

The needle itself is pressed on the speedo shaft. You can hold the shaft and gently rotate the needle to be more accurate. You must partially pull out the cluster and remove the clear lens to access. If the odometer is accurate then the needle is mispositioned on its shaft.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

Are you certain that the speedo and rear gears are both origional and matched? I had that same thing happen to me when I changed my speedo due to a bad odometer, found out the speedo was for a different rear end gearing, so I had to use it for parts and repair my origional one. By time I found this all out the car had been crushed...dangit, woulda been nice to have had that rear end and lose these 3.69's

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

How does it read at low mph ie 10 -20mph?

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2000 VW Jetta TDI with 213,000 miles and climbing
84 300D non turbo getting ready for wvo conversion

this made me think about my 85 Cali 300D, because it is off 5Mph (at 75mph it reads 80mph), and at 0-20mph it jumps up and down and then levels off at around 30mph. not sure if they are related.

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

Funny you guys mention this.. since I'm having a similar problem.

My car is a Euro 300D (1984), and was converted to a US Speedo for import back in the 80's, I'm guessing. Anyway.. I recently got a GPS and used it to check my speed against my cluster.. what do you know, it's off by about 5-8mph. But wait, it gets weirder..

At 0 - 40mph, it's just about perfect. Speedo will read 35mph, and the GPS confirms I'm going 35. From there, it seems to increase in inaccuracy exponentially. At 55mph, I'm going about 58. At 65, I'm going about 70. At 75, I'm going 81.. and at 80 (if I'm able to get this beast UP to that speed), I'm going nearly 88 mph. What the heck is wrong with this thing? This is a real mind boggler.. and the only thing that *I* ever replaced in terms of the speedometer, is the speedo cable when the original one snapped.

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(Oo{=|=}oO) 1983 MB 300D USA, 212,000mi. 80's yellow/white. "Gunther"
(Oo{=|=}oO) 1984 MB 300D Euro, Turbo Added in Germany, 186,000mi [SOLD] Missing her dearly.
(Oo{=|=}oO) 1984 MB 300D USA Turbodiesel, 269,000mi. [SOLD]

The speedomoter reads 50% off at every speed. I originally thought wrong tires (there not), then I thought perhaps the differential gears were changed: the fact that the odometer works accurately rules that out I think. If the needle needed to be adjusted, wouldn't the indicated speed be off a set amount at every speed (say 10 mph regardless) instead of a certain ratio?

I actually have a similar problem but reversed. My Speedometer shows about 20 MPH less. The car is a 85 300D I guess the speedo is from an older model.

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72 280SE His Majesty

I have an 81 300 TD Wagon with a 4 speed manual (stock? I don't know). My speedo is pretty accurate up to about 30 mph. Then, like Zerohour3K, it gets exponentially worse - reading slower than I'm actually going. When I checked the speedo against the mile markers, it showed 9/10 of a mile for every actual mile travelled. I guess this means the car has more actual miles than the odometer shows. What can we do to correct this?

That jumpy speedo means it is very likely the speedo was removed to repair the odometer at some point....when the needle mechanism gets moved around while it is out of the cluster it messes up the low speed functioning...I figured this out the hard way on 2 speedos and next time I'm taping the needle down before it comes out to prevent because it is annoying.

John

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John Hughes, was in Landstuhl, Germany but currently in San Antonio, TX


1978 280CE Astral Silver now 59,xxx miles and counting "Silber-Kugel"
1986 300E Black Pearl Metallic 143,xxx miles 5-spd daily driver w/ blk leather "Schwarz-Schönheit"
1989 190E 2.6 (euro) 5-spd Desert Taupe 112,xxx kms Had to leave behind in Germany!!! "Helga"
1983 300D Pastel Beige now 312,xxx + miles SOLD

OBK#24

I've also got the same problem as Zerohour3k. Accurate up to around 35 or 40, then it seems to be progressively lower than actual speed as the speed increases. I haven't tested the exact variance yet, but 50 seems to be about 60, and 60 is something like 80ish. I know someone monkeyed with the cluster in the past as the black backing on the speedo is bent on one side.

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Obiwanrazzy
1985 300D 267k and hemorrhaging...

obi: Wow! Yours is *really* bad.

Mine does get exponentially worse, but not quite as big a variance of 10mph+. Like I said, on average, 55mph = 61, 65 = 72, and 75 = 83.

Yet, on the slower speeds, it's pretty much dead-on. I guess this could kinda explain the poor gas mileage that I've been getting.. my odometer is probably off by a few miles! Okay, it isn't exactly "poor" mileage, but I'd rather get 28-30 highway, than the crappy 23-25 that I get right now. Probably doesn't help that I have a lead foot, and the car has no turbo / a non properly-functioning turbo.

Anybody have a way to fix this speedo issue?

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(Oo{=|=}oO) 1983 MB 300D USA, 212,000mi. 80's yellow/white. "Gunther"
(Oo{=|=}oO) 1984 MB 300D Euro, Turbo Added in Germany, 186,000mi [SOLD] Missing her dearly.
(Oo{=|=}oO) 1984 MB 300D USA Turbodiesel, 269,000mi. [SOLD]

I keep telling myself that this is the reason for my poor mileage too... Only I'm getting 16-20 mpg. I'm thinking of sprinning for a GPS just to set my mind at ease.

Of course my mileage has nothing to do with the leaking fuel return lines or the dragging brakes.

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Obiwanrazzy
1985 300D 267k and hemorrhaging...