Good afternoon folks!

When I bought my 4-speed manual 240D, the speedometer didn't work at all.

Crawl under the car to see that the speedo cable was not plugged in, (I shudder to imagine now many undocumented miles there are on this thing lol).

I go to plug it in, but the cable has a flat pin whereas the tranny wants a square pin. As a temporary measure, I ground down the flat pin until it fit into the tranny.

With the car up on jack stands, I put it into first gear, give it a bit of gas, and while I see the odometer reading going up steadily, the speedometer does NOTHING until I have my foot down in 2nd gear.

Research on the internet made me conclude that perhaps the magnets in the speedometer may have weakened and thus I need a new speedometer. Problem is, such a thing is very hard to find here is very expensive for one that might or might not be in worse shape.

However, my other problem is that I don't know for sure that the speedometer is the problem. From the looks of it, this car used to be an automatic that was converted to manual so maybe the speedos are calibrated differently on the auto models? Again, not even sure the cluster is original to the car either. My diff gearing is 3.69.

Rather than trying to make the current speedometer work, I wonder if I can install an electronic sender somewhere and use an aftermarket gauge that can be adjusted on the fly.

Any insight on this? I don't know which course of action is more realistic. I am convinced that my current speedometer is just worn out magnetically. But before I go looking for a replacement on evil bay, I'd like to investigate other potential causes to the issue as well as other solutions.

I would be happy with using my iPhone as a gps speedometer, but that's not likely to fly for an MTO safety inspection.


Sent from my Nexus 7 using Tapatalk 4

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1982 240D 4-speed
2013 Jeep Wrangler Sport - 4.10 e-locker

Is round wire connection attached to speedo?

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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!

I really suggest getting your cable replaced with the proper one. I did a 4 speed swap and had a bit of difficultly finding a speedo cable with the correct square end, on the transmission side. I'm guessing that the square slot is just spinning around your ground square end, and only forcing the cable to rotate when it is going much faster, like you suggest while in second gear.

New cables can be found on eBay for cheap.

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1982 300TDT
1991 190D
2022 Metris

I would guess also that the problem is your Spedo cable.

There is two cables depending which Chassis you have, or which Transmission was used.

1977 - 1981 is the two piece, with the seperate bell housing and the iron box.

1982/83 used an all one piece aluminum case.

So 123-542-03-07 was used through chassis # 10-219674. I would guess this is the older Transmission.

list 123-542-77-07 from chassis # 219675. I would guess this is the all one piece aluminum cast trans.

Pellican does not show a spedo cable for our old cars. I searched for speedometer cable, and nothing came up. I found this info on the AZ site.

I doubt that there is anything wrong with your spedo. However the Pot metal Gear might be slipping on the shaft. the Odometer wont record your miles, but the Spedo should work.

Buying a used spedo off e-bay, you need to know what part# spedo you have. A lot of the sellers will say it fits 77 - 85. that is true, however the Spedo is geared to the Differential ratio. your 240 is a 3:69. 300D 77 to 81 is a 3:46. 300D 82 - 84 3:07 and 85 is a 2:88.


Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

While I agree the speedo cable should be replaced with the proper one, I don't think it's slipping inside the transmission.

I say this because it seems like my odometer is operating properly, counting up steadily - but the needle does nothing until I punch the pedal.

Either way, I'll be replacing the cable

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1982 240D 4-speed
2013 Jeep Wrangler Sport - 4.10 e-locker

Also, ensure the the speedometer cable is fully tightened on the back of the speedometer head. I had the same problem and discovered that the speedometer cable was not fully engaged with the speedometer head. I also agree, a new speedo cable is worth the small investment.

Sometimes the yellow paint on the needle gets soft and sticks to the resting pin at ZERO MPH/KPM.

My C280 does this such that the needle does not function until its at around 19 to 20 MPH.

If you can pull out the speedo unit and open it up, then place a small plastic tube (sheath) over the resting pin. That seems to disallow the needle from sticking.

just a thought..........

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD