I have a 1998 Chevy Tahoe LS. I have changed the thermostat, water pump and radiator. The reservoir bucket has rust inside on the walls. The truck is still running hot and no heat pumping through vent
This may be because heater core is stopped up,the coolant has to circulate through heater core to cool the intake,and is not doing it,this is why you don,t have heat in truck all so,you can by pass the heater core for now untill you have it fixed,should solve your running hot issue.
Sounds like the cooling system needs a good cleaning. Flush the system using a chemical cleaner such as Prestone Super Flush. But be prepared for something to spring a leak. Chemical cleaners are great for cleaning out cooling systems clogged with rust and scale but if you have a weak spot in the radiator, water pump, heater core, etc. it's going to start leaking. I only use these cleaners when, like you, there's an issue with the cooling system. Otherwise I just use plain water. Be sure to follow the directions on the bottle of cleaner for best results. HTH. -Jim