I tried to post this yesterday and for some reason it did not happen. I just completed a coolant system upgrade, original radiator rodded, high flow thermostat, replacement fan, and after installing all of this for some weird reason my Disco's transmission will not function. Shifts at the console correctly, but willl not go into any gear. At first, after the job completion it did shift reluctantly into gear, but would slip and downshift. Now it doesn't do that. Why in the world does a coolant system service cause a transmission failure? Does anybody have any suggestions before I drag it to a transmission shop?

 

Check the ATF level!
When you removed/replaced the radiator the Automatic Transmission Cooler Lines had to be removed
from the Drivers Side (LHD) of the Radiator.
Normally you won't lose much ATF, but if the fluid was already low this could be your issue. Good Luck!

 

Your trans fluid level may just be low. Check the transmission fluid level when it's cold and running in park, apply the brakes and shift through all gears P-R-N-D-3-2-1 with 10 seconds on each gear then shift from 1-2-3-D-N-R-N with 10 seconds on each gear, now apply the e-brake and check the fluid level again if it is low apply fluid also make sure the vehicle is on leveled ground.

 

if its not low fluid
check the shifter cable where it connects to the tranny - little cotter pin can rust and then the cable pops off the arm and no shifty
if not that then I would verify that the cable is indeed moving when some one is shifting
verify the transfer case shifter is correctly in a range

 

Thanks for the replies...I did lose a little ATF when the lines were removed, and I guess that was the cause of the failure, although I have never had issues with this sort of thing before. I had it taken to an AAMCO place yesterday so they could do a diagnostic check, which turned out to be a joke, as they just started it up and said the tranny needed to be rebuilt. But they did mention that when they first started it this morning the truck ran fine! Then as it warmed up it started to slip to the point where it would not move. That leads me to believe that the pump may have been marginal and it failed with that little bit of low fluid the other day Anyone ever been into these ZF units before that has any insight? Anyone rebuilt one? I am considering tackling a rebuild. For the time being I will probably drain it and pull the pan to see what is going on. In the meantime if anyone has a line on a good used transmission please LMK. I don't want to give up on this truck, I really like it and have done a lot to make it pretty nice (just ask Paul Grant about the parts I have purchased for it!)

 

Search your local Craigslist for parts trucks and transmissions. ZF 4HP22 step by step. | Classic Rover Forum