I have a '93 Mazda MPV that sprung a coolant leak from the housing that the Lower Hose connects to. This housing has a small-diameter hose coming off of if that goes to the housing where the Upper Hose is connected.
The Lower Hose Housing also has a passage, obviously, that lets coolant into the engine.
The housing also has a theromostat inside of it. I've done my share of engine work, but I'm not familiar with a thermostat in the housing where the Lower Hose is connected. I know all about the housing where the Upper Hose is, and the thermostat that goes there.
It looks like this housing diverts coolant during cold-temp operation (initial warm up) to the intake, or other such system, to warm it faster than might happen if the lower hose simply was connected to the block -- which is the method I'm familiar with.
What is the default state of the t-stat in the lower hose housing? What does this t-stat do? Since I'm scratching my head over this part, what are the symptoms associated with its failure? Does this t-state replace the one I expect to find in the upper hose housing, or is this one in addition to that one?
FOR THE RECORD It looks like my only problem here is that the mounting bolts were a bit on the loose side, and the gasket gave out.