Problem about 1997 Toyota Corolla

Random overheating problem, runs fine for a while then the temp shoots up. Flushed system. Replaced radiator, thermostat, did a full tune up. Water pump is working fine.
I checked timing, it is a few degrees advanced, but there is no way to adjust timing.
Is it possible the crank sensor can move throwing the timing out?
Is there a technique for getting all the air out of the coolant system?
Engine runs fine, ideles smooth.
I am thinking the problem is an air lock or the timing is off…

Even with all the stuff you’ve done (which is all on the right track), the cooling system might still not be holding pressure. If it doesn’t hold pressure it will overheat in certain situations. So that’s one thing to check. Another, when it overheats is the engine cooling fan spinning like a banshee? Pop the hood and make sure. If it is not spinning to beat the band, find out why, b/c electric fan problems are a common cause for overheating. Timing a little advance not a likely cause. Timing overly retarded can be though. Still, I doubt the timing is the problem, unless you’ve changed out something associated with the crank sensor or repaired something that would affect the valve timing. You should be able to get all the air out of the cooling system on a Corolla by driving the front wheel up ramps (like is done by diy’ers to change oil), then open the radiator cap and let it idle until it reaches operating temperature (5-10 minutes) and the upper radiator hose is hot. Make sure the heater is on full heat as part of all that. Replace the cap, and that should do it. While you are doing this, look into the radiator (wear eye protection) to see if there are lots of bubbles coming up through the coolant from below. If so, you may have a head gasket problem. A coolant system pressure test could also id a head gasket problem, among other tests. What sort of driving conditions does it overheat? And when doesn’t it? What tests have you done to confirm the water pump flow rate is to spec?

No offense, but are you sure you’re checking ignition timing the correct way?

I seem to remember you have to bridge 2 pins before hooking up the timing light

at least that’s how it was with my 1995 Corolla, which is the same body style as yours

I agree with George’s comments :smiley: