Yes, on some models the tranny cooler is before the impeller and should not be used. Proper alignment of the shaft is also crucial. A bent shaft , even if only .003 out may cause premature failure. As far as using hot exhaust water for cooling or post tstat water ,it will be 160degrees plus once the engine heats up and worse on a hot day when lake water is 80 plus. Once i switched from post tstat as recommended to pre tstat all leaking around the housing stopped. .02
