Overheating...temp gauge goes completely to the top&heating coolant light comes on...,no leaks..how can i tell if it's the thermostat or the water pump??

If your coolant overflow is bubbling then regardless of what your gauge says you are having overheating issues. If your coolant is missing with no aparent leaks then you need to check your oil for a milky consistency and apearance which would most likely point to a blown head gasket. This would also explain overheating. Hope this helps

It is one of he things you mentioned.
LEAK: Check the water pump itself. The seal might be gone.
CIRCULATION: Check water pump and thermostat.

The slow rising temp gauge points to a thermostat which has failed and stuck open. This is easy to replace.

At the same time the gauge will tell you if the car is overheating.

Is it losing coolant at all? A hot smell can result from leaking coolant getting on the exhaust manifold.

The smell can also result when leaking engine oil gets onto the exhaust. Camrys of that era had several characteristic oil leaks

- from the rear of the cam cover, especially on a V6
-from the distributor shaft o-ring
-from the oil filter-to-engine block mounting adapter (if fitted)

Your radiator cooling fan will only come on when the engine temp has reached the point where it needs to have air forced through the radiator and thus bring engine heat back down to safe operating range. If your heater is not working check to make sure the fresh air vents aren't stuck open (are the controls stiff or not going all the way across?) check also that the heater shutoff valve lever which is usually situated on the firewall at the rear of the engine and can be found easily by tracing the hoses back from the thermostat housing aren't bent and/or seized up.

Sounds like sticking thermostat. Replace thermostat if you see no leaks anywhere else.
You need to drain out any bad coolant or water when you replace thermostat and refill with concentrated antifreeze until you have at least 50% antifreeze water ratio.
You have to bleed the engine with new antifreeze solution so there's no air. I always go to youtube and see how mechanics do each engine bleed. Search your car and engine and `coolant flush'. don-ohio

Sufficient coolant? Check the coolant reservoir first. Then, WITH THE ENGINE COOL, undo the radiator cap and check the coolant level in the radiator itself. Fill completely full as needed.

Any noises from the water pump? It may be failing, although a small leak is usually present and you say there's no leaks.

Remove the thermostat and check it by putting it in a pan of boiling water. Does it open like it should? If not, it needs to be replaced.

You CAN run an engine without a thermostat but it will warm up very slowly but that would be a good test to see of that stops the overheating.

Do you have a temp gauge in the dash? Or just a warning light? Do either indicate overheating. If they do, turn on the HEATER [not defroster] and see if the temp goes down or the light goes off. Your radiator may be partially clogged and the heater core will act as kind of a secondary radiator.

check top radiator hose goes to thermostat housing sound like its leaking if your engine leaking from left driver side on top of engine it has to be top radiator thermostat hose leaking.wait until engine cool down replace top radiator hose see if coolant leaking still occur if so you could have radiator leak.

Hi,

The overheating and lack of cabin heat both point to a failed engine thermostat which would be stuck closed. At the warm up stage, the coolant stays in the engine block to bring the engine to efficient operating temperature, then it opens and circulates the coolant through the radiator and heat core. If the thermostat is stuck closed, the engine will overheat, and coolant will never reach the heater core, and you will not get cabin heat.

Blinking oil light at idle which goes away during driving could be a low oil level, but may also be a drop in oil pressue. You could have a clogged oil fliter (at best) pickup tube, or a failing oil pump.

You are describing a slow coolant leak and the resultant no heat and blockoverheating symptoms. The no heat is because there is insufficient coolant to cycle through the heater core, and the chuggin you describe is the engine indicating serious overheating.
With engine cold, you must add water--not anti-freeze--to the radiator itself, until it reaches the top of the radiator, then start the engine. If you do not have a radiator cap in addition to the overflow bottle (some vehicles don't), you must still add water to the radiator, even if you have to bypass the overflow bottle hose to do it. Add water until no more will go into the radiator. Start engine, let idle until operating temperature is reached. Thermostat should open and a good bit of the water will "sink" into the depth of the radiator. If you have no radiator cap, observe the temperature guage. When it reaches normal operating temp, when the thermostat opens, the temp will drop briefly at first, and you will notice warm air from the heater/defroster.
Once engine is warm and known to be full of water, seal radiator cap and/or system, and let idle for 30 minutes. Use this time to locate the "mystery leak." They can be very hard to find, and some won't leak until after the engine is turned off. During this idle period, observe the vehicle exhaust from the tailpipe as well as looking for actual water leaks: sometimes a bad head gasket can be diagnosed this way; if the exhaust is white and thick like steam, and smells like anit-freeze, you have a more serious problem. It is possible that after the repeated overheating cycles you have endured you may now have both a "mystery leak" and a blown head gasket.
Once leak is located, your next step is to let engine cool completely, drain the water, fix the leak, and then and only then add new antifreeze of the proper rating and ratio recommended by Chevy for your vehicle.
Anytime you drain a cooling system and refill it, it is necessary to check the overflow bottle at least 3 times in the first week after repair to ensure that you have the proper coolant level, and have not either missed another leak or not correctly repaired one. You MUST check it before you drive the vehicle the second time after the first repair attempt because it is normal to need to add more coolant than you added initially after the repair because of air trapped in the cooling system that will only be expelled after the first start/stop heating cycle. If after 1 week of daily normal driving you have only added a little more coolant once, and there are no more problems, you can be very comfortable that you have fixed your car.

If engine is overheating then check coolant level and thermostat first, then water pump. If engine is not overheating then check coolant temp sender for gauge.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/thomas_c50676e836a18949