I have a 2003 Mazda B2300. The truck started overheating due to crack in upper radiator hose connector (plastic!). The radiator and hoses were replaced, and the cooling system was refilled. However the coolant does not appear to be flowing through the system. The thermostat was removed and replaced, but the coolant would still not flow through the system. The 'guts' of the old thermostat were removed and the truck runs a little cooler than it's supposed to, but everything seems okay otherwise. Anyone else have a similar experience with this truck (or a Ford Ranger)?

 

If it wasn't flowing, your temp be getting hot. You just said it is running cooler than it should.

Now that it is circulating and perhaps drove out an air bubble, you might now put the thermostat back in and see what it does. You can test out your stat in a kettle of water you slowly bring to a boil, with thermometer (like a meat or candy thermometer) in the water, and see if the stat comes open when it should, so you can rule that out.

 

Thanks I will put the stat in boiling water to see what it does. The truck was running hot before removing the thermostat - started running cooler after removing the thermostat.