So I just picked up my scion tc, and everything is going well until recently..

My heat...does not come on unless the car is moving and running. Also, my engine temperature gauge is all over the place, at one time all the way up in the red, and then I would stop, and it would go back to normal. My first reaction, top off the fluid. So I did. Topped off coolant, but not it's still happening. Erratic engine temperature and heat. Also, what I don't get, when the tempurature says car is super hot... which i don't believe, my heat is blowing cold air.. wtf?!? Someone please shed some light on this. Warranty does not cover these issues.

Edit: my Mods are HID headlights and Foglights... doubt that's an issue.

 

Maybe you need a new thermostat.

 

any codes?

 

No codes or lights, and having my heat blast cool air, and sometimes hot air and sometimes warm air... I feel like they are related.

 

try changing ther thermastat cheapest and easiest fix if it works. be carful letting your car climb to the red on the thermostat gauge that happened to my car and i ended up cracking my head. it was from a leaking radiator. hope that helps out

 

Sounds to me like you have an air pocket in there somewhere. Sometimes they are hard to get out but easiest way I have found is to top it off and leave the cap off. Let the car run till the fans kick on and you should see some bubbles when the thermostat opens up (if you have air in there) and keep topping it off. Let that happen about 3 times and put the cap back on. Should be good to go. Or most cars have a bleeder valve that you can open when the car is hot and it should get rid of that air but I don't know where or if there is one on the scion.

 

Thanks guys. Looks like there is a leak in or around my heater core. Car is dripping coolant onto my driveway. I am going to get under there after work and see if I can see any loose fittings. The dripping seems to be coming from the middle/rear of the engine bay plus I can smell coolant coming from the cold air blowing from my A/C when the heat is on....thus my preliminary diagnoses of heater core area leak. I will top off with some distilled water until tonight or tomorrow when I can get it to my mechanic.

 

I topped off and I am going to opt from turning on the heater until tomorrow. I'll drive around and see what happens.

I'll keep everyone posted.

 

Blown head gasket. Covered by warranty. Rolling around in a sweet Carolla loaner now. WOOP WOOP. Lesson here: IF you have cold heat blowing, Add coolant. If it still does not work. You blew a head gasket. :D UNTIL NEXT TIME.

 

Actually no to your lesson, if you have "cold" heat, then there is an issue. If the overflow is reading correctly then don't top it off. There is no reason to top off just because it's not hot/cold.

First thing if you get cold air during a heating operation, you'll likely have a thermostat issue. It's really rare for a head gasket to leak outside of the motor and onto a driveway. Always check your oil if you get no heat or you are overheating. And your car has to be running to have hot air coming from the vents.

 

I second the no to your lesson. Toyota engines don't just blow head gaskets. Some engines(*cough* northstar v8 *cough*) go through them like clockwork but in the 2az it should last the life of the car. That is unless you do something dumb like driving with the temperature gauge pegged. My best guess is that you had a bad thermostat which prevented coolant from flowing to the radiator which led to the engine overheating which in turn warped your head or block(or both) resulting in a blown head gasket. The real lesson is DON'T KEEP DRIVING IF YOU OVERHEAT.

 

Didn't expect people to take that so literally... I should have cautioned: For lolers purposes only.