Speedo and Tach problems

[Jmana]

The tachometer doesn't work and the speedometer stops working at about 55 miles an hour on the 82 300SD I bought. What would be the culprit? The odometer is also broke (of course).

[carwithfarts]

check and make sure ur speedo cable is conected tightly on the back of the cluster. if it is then jack up the car and check tward the rear of the tranny for the speedo cable and make sure the connection is tight. if it still doesnt work check the diy resources in the forum to repair the odometer and while your there peak in and check to see if the gears are stripped in the spedo section. if not you may just have a bad cable. coneact you dealer or fastlane for a replacement.~Luke

[jpchleapas]

Originally Posted by Jmana

The tachometer doesn't work and the speedometer stops working at about 55 miles an hour on the 82 300SD I bought. What would be the culprit? The odometer is also broke (of course).

You can do a search for speedometer repairs in the archives. My speedometer in my 1983 300SD was accurate on my mph, but the actual miles driven was not registering. It cost me $150 to have it removed and sent out for repairs and then reinstalled by my mechanic. While the gauge pod was out I asked him to replace the 5 burned out dash bulbs that are very low cost. Your tach is most likely like mine that goes in and out, or it stays dead. It is most likely by what I have read the small VDO speed control sensor. A brand new one is only $68 from ******** http://www.***************/search/productx.aspx?sid=0j5jwdyumamhtfvg20wcsq3m&makeid=800016@Mercedes&modelid=1194027@300SD&year=1983&cid=18@Electrical%20%26%20Vacuum&gid=3988@Speed%20Control%20Sensor
It is very easy for you to find under the hood in what looks like a small trash can on top of the fender under the hood right out in plain sight. My mechanic popped open the lid just to show me how easy it is to replace it. That repair I can do myself since it is simple to do. Do some searches here for information. There is also information in the archives here on cheap thrill repairs for the speed sensor to at least temporarily to get it working again. My cruise control works good on my car and the previous owner who replaced the engine and transmission did a lot of the work. I am saving my energy for the repair battles I know I can win like replacing my interior door panels to start with. I am very impressed with how the car runs so far. The cruise control is a nice feature for the highway. I think the tach might be a part of that so I want to replace mine asap.

You can send your speedometer out yourself to the same guy my mechanic uses in CA at: http://www.speedometerplus.com/
The speedometer DIY repairs are found in searches. It is not worth my time to try to align the numbers up correctly. I am saving my strength for the easy work like seals around the rear tail lights, trunk weather seal etc. The rear end fluid change is also on my plate for another easy job I know I can do myself. I want to pick the battles I can win to start out with for repairs to build my confidence. My starter is about due for replacement. That is one of the parts I will not skimp on and buy a good remanufactured one. I am happy that I have a friend with access to a lift who will help me if I get stuck when I do the starter. 30 years ago I worked in a garage. My oh my was that a long time ago when cars still had points. I still remember one car with a killer top bolt hard to get at on a starter replacement I did by myself. By what I have read the starters are one of the PITA jobs we can do on our cars. I have printed out the repair info on how to do it, and I will also bring along my laptop with the MB repair CD loaded up to guide me along also. I smiled when I first looked at how clean and uncluttered the MB engine compartment looks under the hood at first glance, very much unlike my Dad's Town Car, or my EFI Mustang.

For replacement MB gears for the DIY speedometer gears.
http://www.odometergears.com/
John
1983 300SD 183,000 miles