I don't see any external coolant leaks in my 1996 Dodge Dakota 4X4 3.9 liter five-speed (purchased new from the dealer and now with 295,000 miles on the odometer). Nonetheless, driving less than 200 miles a month this summer I have added coolant to the recovery tank on several occasions. The temperatures have ranged from a high of 90-100 to a low of 78-80 during this time period. I wonder if other Dakota owners who live in warm/hot climates are experiencing the same thing? I really don't know how much "coolant" (I use a 33% concentration) can evaporate from those plastic reservoirs and how much the coolant can be lost by way of other means (maybe a small head gasket defect?).

 

Might be something as simple as a clamp that isn't as tight as it should be. The bypass hose is also a notorious leaker, and given its location, you may never see coolant hitting the ground...... Could pressure test the system, and see what happens....

 

When you added coolant, was the radiator low or just the overflow tank?

 

Good question, I removed the radiator cap and the radiator itself was completely full to the brim.

 

Drive it for a bit with an eye on the temperature gauge. If it doesn't go down much, you have a bum tank. It will expand to the tank a little and if that is leaking, you might lose a little bit of volume. I'm just guessing but I'll bet you have a crack in the tank. Either somewhere along the seam where it was made or down at the place where the hose connects. It's plastic and over time will weather and just age out. I've seen them so brittle just trying to unbolt them will have them shatter.

 

To further HYs point, I was also losing coolant in my '93, 5.2L. One day I was under the truck farting around with something and I noticed the hose on the bottom of the radiator going to the tranny wasn't clamped tight. The damp coolant around the hose was the giveaway. Cinched her up and that was the end of that problem.