We have a storm system moving into the area today. When I went out to my shop this morning the floor was wet. It was like a lake in there. The cool concrete meeting the warm moist air produced condensation. That got me to thinking about the t-case heating problems. I know that a lot has been written about it and it boils down to some do and some don't. The ones that do seem to be relatively low milage units. They also seem to have almost too tight of tolerances. How many of you with one that gets hot know that they were fire trucks? Here is my theory.

The truck sits for days at a time. A call comes in about a brush fire. The truck is fired up, driven as fast as the driver dares to the fire. It does its job and then is driven at high speed back to the station. The truck then sits for up to days again. While it sits, it mighted get washed, the regular fire trucks get cleaned, equipment gets hosed off and moisture is present in the air. The regular fire trucks go on more calls and get cleaned several more times. The cast iron t-case just sits there at normal air temperature. Moisture in the air condenses around it every night. Some of that moisture is inside of the case. Condensation eventually turns to rust or at least surface rust on the gears. Every time the truck gets used, that rust is cleaned off and becomes part of the oil. That oil circulates the particles all over the case. I don't see how changing the fluid will flush all of the small stuff out. I think everybody will agree that any machined surface that has had rust on it is changed forever in at least a small way. Look at guns. If it is not completely stripped down every time you clean it, rust and corrosion will form on the neglected parts. When you do get to the neglected parts, no matter how much you clean, they are never as good as new again. That is why I think that old fire truck use M715's have a better chance of having a hot t-case. That is part of my theory. I didn't want to get into a science lecture about dew points and relative humidity and such.