+1.

On my previous Ranger this was the issue. I was also picking up a slight coolant smell that told me it was leaking somewhere, but it took forever to find it.

The pinhole leak idea can also account for it.

__________________
- Current: 2010 Ranger XLT 4x4 in Redfire Metallic, 4.0 L V-6, 3.73 ratio final drive, Cooper Discover HT P255/75R-15's, automatic, all-power.
- Previous: '90 Ranger XLT 2WD, 3.0L 5 spd (traded), '93 Ranger XLT 2WD, 4.0L Auto (traded), '01 Ranger XLT 2WD, 4.0L Auto (traded)