1993 ford ranger 3.0 A4ld transmission

[Tooter]

I recently bought a truck from older gentleman 44,000 original miles. the transmission fluid all ran out replaced filter and transmission fluid and it will not pick up pressure to move reverse forward or anything and it worked fine till it was parked. Any ideas?

 

[Shran]

Do you have enough fluid in it? What does it show on the dipstick? Usually there is only one side of the dipstick that is accurate. So if you pulled the pan and drained it all, you will probably need to put in at least 4-6 quarts before it comes to life.

Did anyone try driving it with no fluid in it? That could have burned up the pump. Hope that's not the case.

 

[RonD]

Welcome to TRS

Engine off
Check trans fluid level, mark it
Engine running
Check fluid level, if its lower then pump is working, if its the same level then there is no fluid pressure


All automatics run on fluid pressure, A4LD needs minimum 75psi to go forward, 125psi for reverse, which is why reverse goes out first if there is a problem with pressure, on any automatic
The pressure is provided by the Pump which is directly connected to the engine via Torque Converters outer shell
The fluid, under pressure, is sent from the Pump to the Valve Body
Valve Body routes the fluid to engage clutches and bands(brakes) in the main drive(rotating part of transmission) this causes the forward or reverse engagement/movement(i.e. manual trans has no movement unless clutch is engaged)

Valve body has gaskets, and seals for passages, and all the valves have seals
If trans was left "dry" for a long period then these gaskets and seals will dry out and no longer hold pressure, so there is not enough pressure to engage clutches and bands, so no movement

See if you have forward movement in 1st, manually shift to 1st, if you do that's actually a bad sign, lol
There is a port on the outside of transmission that is there to test internal pressure, gauge needs to be at least 400psi to be safe

Diagram here: https://www.explorerforum.com/forums/media/a4ld-specification-chart-from-transgo.39537/full

There are products called "trans fix", they all do the same thing, they swell gaskets and seals to try and get them to stop leaking pressure, not really "a fix" but can restore movement if pressure can get high enough

You can also replace valve body gaskets and seals with trans in the vehicle, which is not a waste of time or money, because if there is a problem in the rotating part, so have to pull transmission then you will have the rebuilt valve body part already done.

When you drain current fluid check it for metal bits, if found just pull the transmission, rotating part needs servicing