Need help on a leak

[mtnrgr]

it

 

[RonD]

Did you replace the mechanical/VSS unit on the transmission?

'94 would have the dual unit, mechanical cable for speedometer and VSS(vehicle speed sensor) for the computer, cruise and ABS.

This unit has seals inside to prevent trans fluid from entering the cable.

There is a picture of the unit here: http://www.therangerstation.com/tech_library/speedometer.shtml

The cable can act as an archimedes' screw, and draw fluid up to the dash board connection, but there should be no fluid in the cable, so my bet is that the seals at the transmission end are the problem, not the cable itself.

Make sure trans fluid isn't overfilled, that can build up higher pressure than normal.
Most manual transmissions vent thru the shift tower, not sure where vent is on the M50D, if the vent is clogged up there is a chance that, as the trans fluid heats up and expands, the pressure isn't being vented and fluid is being forced passed the seals on the speedometer unit

 

[RonD]

I added to my post.

I would disconnect speedo cable, at transmission end, clean fluid out of the mechanical drive, then drive it a bit to see how much fluid is leaking and when.
You could also put a reversible drill on the speedo cable and run it at low speed(same as driving in Reverse) to draw out any trans fluid still in the cable.
As for the check, stop after a few minutes of driving and check it, if it isn't leaking cold then drive it for 1/2 to 1 hour to heat up trans fluid and check it again, if that's when it leaks then trans is over filled or vent is plugged.

If it leaks cold then seal in Drive gear / VSS is bad.
New no longer means "it works"
New now means "never been tested", although I would tend to trust Ford parts, as far as I know they still have Quality Control on parts, but that doesn't mean they check every part.

 

[96Indyram]

I'm sorry I dont have a "correct" fix for your problem, but can offer a redneck fix.

I am not sure how it all works on a 94 .
You Might be able to disconnect the cable going to the speedometer ( the leaky one)
and pull it out of the cab so it wont leak inside the truck. Could tape a pop bottle on the end of it to catch the fluid.
Then get a speedometer app for your phone that uses GPS location for your new speedometer. and drive it till she dies!
I used a app on my phone in a nissan 240sx that had a bad cluster.It is very accurate on speed.

Good luck.