What can cause a y block to not reach operating temp? My car recently started to run colder than usual. With a 190° thermostat my car stayed in the 190-200° range even in 100 ° weather. It started to run in the 150-160 range so I suspected a stuck thermostat. I changed it out with a 180° thermostat and with the cooler temps it barely reaches 150 now. In warmer weather it would barely reach 160. I verified the gauge is correct with a thermo gun. With winter coming on I need to get it back up to normal temp for heat plus it doesn't run well with the cooler temp.

Durham Missouri