1999 Explorer - 3-4 speed slip and sometimes no reverse

[MJSunderlin]

1999 Explorer; 4.0L OHV; 5 spd Auto.

4 months ago the transmission started slipping on initial cold starts, would have intermittent slips (or transmission just not engaging) for the first mile or so then would drive fine no problem. After a month of this I changed out the filter and fluid and it ran fine til a month ago when it starting slipping between the 3rd and 4th gear upshift.

A couple of weeks later reverse starting slipping (not engaging) after it has been driven a while - I can get reverse to function on a cold start though.

The cost of having a rebuilt transmission installed is more than the vehicle is worth itself. I'm willing to try repairing it myself if possible - just want to be sure of which is the right direction to go. I've been told to try a valve body gasket replacement. Am I on the right track or am I off-base and is there something else I should try instead? Any advice would be greatly appreciated.

 

[PopRichie77]

The valve body gaskets would be a good place to start. Does the OD light flash? If it flashes there is a code stored in the computer, get it read and this will help.

 

[drdoom]

+1 VB gaskets.
And if you are going to start working on that transmission, do yourself a big favor and install a proper drain plug.