Confused, Whitish/Very light blue "steam" emitting from engine compartment

[Rmoe3]

Hi, I have a 94 Winnebago Vectra M31RQ Chevrolet 454

I am puzzled with what is happening when under heavy load conditions.

When driving up mountains, and really pressing on her, a whitish/or super light bluish steam like emission comes out from beneath the engine compartment, Passenger side.
Not out of the exhaust at all... This RV has had a transmission cooler added to it, and a Banks S/S Exhaust system.

I have drove behind her when this happens with my vents and windows open and I smell no oil, or petroleum smell to it.. mostly just a vapor smell...
Engine does not sputter or lose power during this occurrence.

I put a new radiator cap on it, but don't know what to check from here...

Ideas??