I'm the second owner of a 160,000- mile 1994 Ranger XLT, regular cab with short box, 4.0 L OHV V-6 with a 4sp-OD automatic. A few months ago, it began shifting improperly and not engaging in gear properly, especially when cold, first thing in the morning. Checked the transmission fluid and found it about 1-quart low, but color and cleanliness were good. I had been advised that it had been changed religiously at 12,000 to 15,000 intervals since new. The 4.0 OHV V6 has never needed oil added between 3,000-mile changes, so I began focusing on the transmission and neglecting oil checks. While ignoring the engine oil level and adding about a quart of transmission fluid per 500 miles, I continued musing about where the fluid was going. Carefully watching parking areas, and even inspecting from underneath the vehicle for any sign of leakage, I found none. I just kept adding transmission fluid as necessary, too busy to think much about it, but still bothered about where the fluid was going. When Christmas came and I was planning a short highway trip to visit my family, I returned to my regular habit of checking all fluids. I found the engine oil level a couple of inches over full . . . the missing transmission fluid. The vacuum modulator for the transmission had developed a diaphragm leak and was siphoning transmission fluid into the intake system, with it eventually ending up in the engine oil. A new transmission modulator solved the problem(s), and the transmission fluids and engine oil stay in their respective places. In addition, shifting is better than I've ever experienced with this vehicle.

 

might have a leak inside the radiator....check the antifreexe

 

Thanks for the replies. I just wanted to alert others of this malady. Everything seems fine now. A cheap and simple fix for a mis-acting transmission. Wish all problems were so simple. Lesson learned: Keep checking all of your fluids regularly.

 

If it was going into the intake it should have been putting out a white cloud of smoke as you drove. I'm sure you've drove behind someone with white smoke rolling out the exhaust. Most times it's the modulator diaphram.