I have the 1994 Mazda B2300 2.3L 2WD pickup which is the Ford Ranger knock-off. I acquired the vehicle 5 yrs ago and it never really heated well in the winter. Several days ago the heater core sprung a leak so I read some of these forums and successfully changed it with new one easily. Still, the heater wasn't working properly and the temp gauge read too cool. Thinking it was probably the T-Stat I purchased one along with new 16 pound rated radiator cap. First installed new radiator cap to test system and now all systems operational - didn't need to change T-Stat. Heater works great, temperature reads normal and holds there, engine performance excellent. Many people do not think of the radiator cap when doing repairs but since liquids perform differently under pressure it is important the correct pressure is maintained in the heating/cooling system for all components to operate fully functional. The spring tension eventually goes bad on the cap negatively impacting internal system pressure. Not bad for a $5 part! Hope that helps.