Dodge Ram 1500 Transmission fluid dissapears - cannot find a leak

I have a 1998 Dodge Ram 1500. The transmission fluid is always low, but I cannot find a leak. This causes the transmission to slip. When I add transmission fluid it is okay for a while. (I do not drive the truck daily…) Any ideas on what the problem may be?

When you are driving down the road you may be losing fluid through a small leak. You can’t, of course, observe that.

Have the car put on a hoist and run the engine and trnasmission. There might be a small seepage. Just because there is no puddle on your garage floor does not meant you don’t have a leak.

Have you checked the coolant to make sure it’s not contaminated with transmission fluid?


IIRC, a lot of Mopar transmissions send pressurized fluid through the trans cooler only when the gear shift is on gear, not in Park or Neutral. Under these conditions, a leak may not drip at idle in the driveway, but only on the drive.

My Dodge Intrepid leaked at the torque converter seal and burnt on the exhaust, but only when I was driving. When I stopped nothing.

Seconding @Tester 's comment, first thing is to make sure it isn’t leaking into the radiator. The transmission fluid flows through the radiator in a closed tube to cool it in most vehicles with automatics, and if that tube springs a leak inside the radiator the transmission fluid will leak into the radiator and mix with the engine coolant. If enough leaks it could damage the engine, so it is important to know if this is happening asap.

I believe that if this is a 4x4 there is a vacuum line to the transfer case. What I don’t know is if the transfer case and the transmission share fluid.