Hey
this is one of the most confusing problems i have had with any car. The car's motor does not feel like its getting any hotter but the car will reach 1/3rd on the gauge and stay there for a while. Randomly 15 minutes into driving the temp will fly (Faster than rpms in first) to the H. I have replaced the thermostat and gone to waterwetter today but it didn't change anything. Maybe its the temp sensor? Fans come on, doesn't leak out of the waterpump, hoses are good, thermostat is good. There is a very very small leak on the upper hose out of the water neck on the motor side. Mists the timing cover after a 30 minute drive.

 

Could be the ECT,mine went out at about 44k miles.

 

Sounds like your small leak may be enough to get an air bubble to pass by the temp sensor. Fix the leak and top it off with coolant and see what happens. Any other troubleshooting will be pointless when there's a known problem.

 

agreed... order some silicone upper and lower radiator hoses and then burp the system

 

Okay thanks guys, ill order the upper and lower hoses today. ECT? i duno what that thing is.

 

Engine Coolant Temperature sensor,its right under the alternator and has a green plug IIRC.

 

Got ya, I ordered upper and lower hoses so i guess i just wait. I am going to burp the system after the new hoses and see if that fixes it. Coolant temp sensor is 14$-42$ at the parts store. Should be a really simple fix

 

I replaced the Sensor, hoses, and bled it. Now the overheating tank fills up. Maybe the cap? IDK
Hoses still pressurize but alot of coolant goes into the tank. it gets filled up. Only heat spikes when i go over 4k

 

are you sure you properly bled the system? it can be a bitch... also, don't overfill...

 

what coolant are you using? stock radiator? when you squeeze th upper rad hose is it super tight like it's going to pop or just firm but gives a little?