A Quick Cooling Question.
 

Over the last month I have over hauled the entire cooling system on my 96 Camry 4 banger engine. After we had a TS stick closed.

The gauge runs just below the halfway point, while on the road..When I get into standing still traffic, it will climb up to 3/4 marks, then the fan kicks on and it returns back to the mid mark, then cycles back up and down.

Is this normal? Reason I ask is before we did the overhaul that gauge didn't move to speak of.

No.

If everything is operating normally the needle should move to just below halfway point as you state and stay there regardless of stop and go, prolonged idle, etc.

Is it possible the cooling system was never up to par before the stuck T-stat? Could the engine have overheated prior the discovery of the T-stat problem?

Assuming since you operated the engine for some time all the air in the coolant system has bleed out (make sure the heater was set to full heat) and the coolant was topped off.

What did the cooling system overhaul consist off? What temp setting T-stat was installed?

The fans typically start up at around 199F the turn off around 181F. You can place a thermometer into the radiator fill port and let the engine heat up to monitor coolant temps. The coolant switch for the fans is at the bottom of the radiator thus temps at the upper tank will be higher.

Determine if the coolant temp really is going up and down as the gauge indicates.

The engine should not overheat at idle nor the coolant start to boil even with the radiator cap off.

Once the engine is up to temp, you should be able to see the coolant move when looking in the radiator fill point. Wear safety glasses in case the coolant burps out which it should not do unless there is a problem.

Feel the upper and lower radiator hoses. They should be within 30F degrees of each more or less but not the top hot and the bottom much colder.

How hot did the engine get and for how long? It is very possible if run too hot for not that long to blow a head gasket on the engine.

The T stat is a OEM Toyota part not sure of the temp range. I can ask the radiator shop what they did on bleeding the system to make sure.

The over haul was three temps sensors, water pump, T stat, upper hose (lower was replaced two years ago) number one fan relay. The radiator was replaced about a year ago.

When this problem started I was on the road and noticed the gauge running at 3/4 when we started to climb a hill it ran into the red, I pulled over straight away and turned off the motor.

I just spoke to the radiator shop and the system was bled, and they tested the system with an with a temp gauge and its running in factory specs. He seems to think that it might be the temp sensor that connect on the upper radiator hose, might be an after market and its not reading at the correct temps.

I have a call into the shop that did the water pump and temp sensor to see where they got the parts.

Please post back with the results.

They used an aftermarket temp sensor. I have them getting an OEM part and that should take care of the temp gauge moving up and down

its a good option but I'm I still think there are some other better options.

Great.

And what are those?