Back engine overheating on ground

[Rickskymaster]

I had difficulity getting started this saturday. I got the back engine started right off, but the front just would not start. After 15-20 minutes, I finally got it going.
During the 15-20 minutes, I noticed that the back engines Oil temp was getting up there pretty high. My friend and I speculated that it was a problem with the Oil cooler, but as soon as we got the front started, the temps went down almost immediately.
Since, I am a new owner of a Skymaster, I am assuming that there was not enough cooling without the front engine running.
I should mention that as soon as we saw the temps go up, I repositioned the plane into a 10 knot wind, without any change. As soon as the engine fired up, boy did those temp go right down.
I will be interested in hearing all of your opinions.
thanks
Rick
N48AT