I have a 96 Explorer, Eddie Bauer 4x4, and while driving, approx 10 mins, the overdrive will automatically turn off and remain off untill the car is restarted. Flashing the O/D off sign. There is no noise except for a winding sound when I start the truck up from cold. Any ideas on what it might be?

 

Well, exploder96, it sounds like you have transmission problems. I have an '02 Explorer that started showing transmission problems back around 140,000 miles on it. I have posted about it here on this forum before and can provide a fair amount of information, but let's address your transmission.

The flashing O/D off light is the car's computer telling you that it has completely failed to control the shifts in your trans and has put it into a limp mode, which is a set of predetermined shift points and usually no overdrive. It is meant to allow you to safely drive the car a reletively short distance, like to a shop or your home. As you may have noticed the limp mode can be reset by shutting off the car and restarting the engine. What's frustrating about the limp mode is that you don't always get an error code in the computer telling you why it was put into limp mode (just one of my pet peeves about computer controlled things).

As to what may be wrong here is my guess. If your mileage is near or above 100,000 miles and the limp mode is happening fairly consistently I would say you have a leak in the hydraulic system of the trans. Ford transmissions haven't earned the best reputation in the last 20 years despite their use of hefty gears and clutches. Their weakness has been in sealing fluid leaks within the trans. In my case, mine leaked around a piston that pushes on the overdrive clutch band. No ability to build pressure means reduced clamping by the clutch and massive overheating on the clutch and associated drum.

So what to do? The problem is easily diagnosed with a pressure gage installed on the trans pump line and then monitoring pressure while in gear (reverse or forward) at idle. I don't know the specifics for your transmission, but mine required a minimum pressure of 90 PSI off the pump. I was only getting 55 PSI. That meant I had a bad leak. In order for you to do this you'll need a tech manual for your trans with pressure specifications and a gage installed (temporarily) that can handle at least 400 PSI.

Overall I'd say you're headed for a rebuild, but be careful not to just have the damaged parts replaced. That's just a symptom of another problem. You probably have a leak and if it's not fixed and beefed where it's leaking it will break again that much faster.

Good luck with this one!