Rep Power: 0

hello, start overheating 2 days ago and happen when i was sitting at taco bell parking idling and add some coolant and shut it off for a bit and drove off fine, this happen two days ago and today happen again. takes me about 20 mins get to work and i didnt notice any overheating till got my job parking lot and sat there for few mins notice niddle all the way to H. i open hood and fan was on and notice coolant reservoir overfilled and kill the engine for a min or two and turn back on coolant reservoir went down and niddle when down slowly. what can it be ?

 
Rep Power: 174

Head gasket most likely.

 
Rep Power: 518

Reservoir going back down doesn't scream head gasket yet IMO.
After the engine is cooled off, open the radiator cap and see if it is completely full of liquid all the way to the top.
If the radiator is completely full, it might not be head gasket.....but if it's been hot it can't be ruled out as collateral damage.

When you opened the hood on the HOT engine and saw the fan was running, was the AC on or not? (AC causes fans to operate too, so I'm wondering if the high coolant temp is what made the fans run when you saw it...this is an important piece of info for diagnosis)

I might look for a blockage of air flow through the radiator and condensor fins (dirt/sand/bugs/leaves/trash/damaged fins), and check for internal deposits in the radiator core (calcium/lime), either would cause a problem with heat transferring from the hot liquid in the radiator to the air being pulled by the fan blades.


You could try using a garden hose spray nozzle to wash out the outside radiator fins, go from the engine compartment side and wash the stuff out toward the front of the car.