Just replaced the thermostat, still over heats, getting no heat out of heater, upper hose is hot and lower is cooler, when shut off truck you can hear it bubble in radiator, HELP!

just replaced the thermostat, still over heats, getting no heat out of heater, upper hose is hot and lower is cooler, when shut off truck you can hear it bubble in radiator, HELP!!

Thermostats sometimes can be put in upside down
The pointed end goes towards the upper hose
Just remove the thermostat and see if it all works fine
Then buy another new one (they will stick when overheated ) and make sure it is in correctly

Otherwise ,make sure the lower hose is not squeezing closed while it is running,---some have a spring inside to prevent this---

Joey

If heat is not coming out of the heater, then there's a problem of corrosion and/or phosphate scale blocking passages in the heater core and probably the radiator. You will likely need to reverse flush the heater core and install a new radiator. Afterwards, refill the system with a 50/50 mixture of the recommended antifreeze (likely G-05) and distilled water. Purge the system of all air.