1997chevy Tahoe overheating replaced thermostat and radiator but still overheats

If your vehicle's radiator is overheating and there are no visible leaks, it is possible that the problem could be caused by a faulty thermostat or water pump. These components are responsible for regulating the flow of coolant and water through the radiator and engine, and if they are not functioning properly, it can cause the engine to overheat.
To determine if the thermostat or water pump is causing the overheating issue, you will need to perform some diagnostic tests and checks. Here are a few steps you can follow:

1. Check the thermostat: The thermostat is located in the engine and controls the flow of coolant through the radiator. If the thermostat is stuck in the closed position, it can prevent the coolant from flowing and cause the engine to overheat. You can test the thermostat by removing it from the engine and checking it for proper operation.
2. Check the water pump: The water pump is responsible for circulating the coolant and water through the radiator and engine. If the pump is not functioning properly, it can cause the engine to overheat. You can test the water pump by removing the drive belt and attempting to turn the pump by hand. If the pump is seized or not turning smoothly, it may need to be replaced.
3. Check the coolant level: Make sure that the coolant level in the radiator is at the proper level. If the coolant level is low, it can cause the engine to overheat.

If you are unable to determine the cause of the overheating issue, it is recommended to have the vehicle inspected by a mechanic who can perform a more thorough diagnostic test and identify the root cause of the problem. They will be able to recommend the appropriate repairs to fix the issue and prevent further overheating.

Bad thermostat

if it is overheating within a few minutes of running first use a laser temp gauge to ensure that the gauge is working. if it is then next step would be to have the block tested. even with a stuck thermostat it shouldn't overheat that fast.

REPLACE RADIATOR PRESSURE CAP AND CHECK THE COOLING FAN CLUTCH.WHEN YOUR ENGINE HOT WHEN YOU TRY TURNING CLUTCH FAN WITH YOUR HAND WHEN ENGINE IS HOT.THERE SHOULD BE RESISTANCE IN THE FAN.IF CLUTCH FAN SPINS FREELY WHILE ENGINE HOT.YOU NEED TO REMOVE COOLING FAN TO REPLACE CLUTCH.

change the radiator please.

The problem with overheat is due to poor coolant circulating. The main culprit is the Radiator. When the radiator is clogging up, coolant can't be circulating. The stagnant coolant inside the engine water jacket keeps absorb heat from combustion chambers having no way to dissipate the heat then the engine is overheated. You can test the water pump by removing the thermostat, then hooking everything back. Open the radiator cap, then turn on the engine to see if water flowing down to several small tubes inside the radiator. If water can't go down fast enough to cause over flow at radiator opening then your 90 Legend Radiator already got clogged up. Replace with a new radiator, not even a rebuilt one. Good luck.

Cause of overheating besides radiators are as follow. Radiator fan. (overheats while stopped). Thermostat. ( overheats all the time).

If when you replaced coolant you noticed taht it fills slowly, the radiator could be internally blocked. Usually it can be flushed or if really bad, replace it. Also have the radiator checked for hydrocarbons...any in there tells you that there is a head gasket problem.

If you haven't flushed your radiator, i would recommend this asap. i would also inspect the water pump and thermostat as well. replace both components if found to be faulty.

Make sure the cooling fan is operational. it should cycle on and off if the air condition is activate.

but is the water circulating ... if not its the water pump or thermostat