Wondering if anyone can shed some light on this: I have a 1988 E350 based RV and the speedometer works when you start out but routinely quits after a few miles / I believe it occurs when the engine and exhaust system reach full operating temperature.

My guess is that it has something to do with the Speedo cable getting hot but that is just a guess. It seems strange that it works when the vehicle is started up but quits soon afterward.

Any ideas?

Thanks

 

Either the cable is going out, or the plastic gear inside the transmission is worn.



Since it does work, but quits once warmed up, I wonder if a little lube on the tip of the cable where it connects to the speedo behind the cluster? Maybe it's dry and once it turned abit and heats up and seizes.

 

Was this ever solved? I have an '89 E350-bases box truck that did the same thing. The speedo since seized, and putting another speedo unit in has not solved the problem. During my swap, I had to pull the cable up towards the speedo head. I did this by starting under the truck and pulling some slack away from the tranny towards the engine bay, then getting under the hood and pulling up on the slack while also feeding the cable into the firewall towards the speedo. I'm wondering if I damaged the cable somehow while moving it. A second question would be can I run a straight cable from the tranny to the speedo, or do I have to go through whatever that cylindrical object is with the electrical connection on it?

I'm going to start a new thread for this, as well, because my search didn't show any existing threads that specifically covered this.