Coolant Contaminated.... Trans fluid?

[EGruner]

On a routine maintenance check I popped the radiator cap to take a look and saw a milky fluid. Question is could this be a mix of transmission fluid and coolant? Oil and coolant? Orange and Green coolant mixed together? The fluid has no obvious smell and is oily, but not excessively. It's not very red, more of an orange, so if it's trans fluid I probably caught it pretty early.

2008 Explorer V-8, 6R60, 4WD, recent exhaust manifold replacements and recent transmission pan drop with filter/fluid replaced... (fluid was not frothy)

Suggestions? (I'm already thinking cracked trans cooler in the rad tank.)

 

[Rick]

The transmission cooler could be leaking into the radiator. Did you check your transmission dipstick to see if it was low or contaminated?

 

[EGruner]

6R60 tranny has the dipstick underneath (under a threaded cap) so it's not as easy as just pulling the stick. I'm going to crawl under it tomorrow. I can't tell if the color of the coolant convinces me that it's trans fluid or engine oil mixing in. There's no evidence of coolant on the oil dipstick.

 

[EGruner]

Was small leak around the quick connect fittings where the transmission lines came into the cooler at the bottom of the radiator. The o-ring on the pressure side was split. New radiator, flushed system... good to go.