I changed my valve body gasket in my 99 4R44E yesterday and no I’m having some issues. The truck will only go into gear if you put it in second gear. If I put it in drive nothing happens. It’ll go into gear if I go to second then back up to drive. I also have no reverse. What have I done wrong?

 

You have lost pressure, Reverse needs 175psi pressure to engage, 1st 125psi

The Front pump makes the pressure, 200psi
The valve body routes this pressure to the clutches and bands(brakes) to engage and disengage them

So something is leaking or a valve is stuck

So why did you change the valve body gasket?
I assume there was already a problem

 

I was changing the fluid and filter as maintenance. The truck has been lagging going into drive. So I figured while I had the pan dropped, I’d change it to see if that fixed it

 

Slow engagement is also a pressure issue, if you raise RPMs and it engages faster that's for sure a pressure issue

The 4R and 5R have an EPC(electronic pressure control) solenoid in the valve body, it doesn't have a pressure sensor but it still adjusts pressure based on engine rpms and gear selected, these can leak or stick causing slow engagement and slipping

All automatics run on ATF Fluid pressure, so most issues can be solved with new valve body
The pump can get old and the clutches and bands(brakes) friction materials can wear out(250k+ miles) which requires a full rebuild, running an automatic that "slips" wear out these faster, like riding the brakes wears out the pads faster

But in general you should have had good results in resealing valve body, I think something got missed, don't know what but you will be doing it again

 

I know this is an old post, but it sounds like you may not have indexed the manual valve correctly with the shift linkage. Ask me how I know that (did it myself). Doh!

 

Hopefully you see this . Would you be able to help me out . I’m in that position right now .