Question about 2007 Scion tC Coupe

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Heater starts to blow cold air, engine temperature climbs.

This started a few days ago. The Serpentine belt was replaced about a month ago. Is this a gasket problem as in "head gasket" or is it something else?

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  • Sandra Brown Jan 12, 2009

    There is no problem with the defroster. The problem starts with the heater. The heater starts blowing cold air and the engine temperature level rises. The car has not run completely "hot", but I want to be sure that I get the correct info...I lost a posting regarding the water heater. Can you tell me the solution with changing the water pump and thermostat. Thanks!

  • Sandra Brown Jan 12, 2009

    Flushing the heater core is a possible solution for getting the heater to work. But what about the fact that the car is about to run hot? Are you saying that doing a system flush should be the first thing to try...

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If nobody has told you yet.Check the oil after running the car and look for white bubbles. If there are white bubbles in the oil water and coolant are mixing (head gasket) Also look at the exaust and if there is white smoke it is another sighn of a head gasket. OR, when the motor is cool take the rad. cap off and run the motor. As the motor runs the coolant level might go down. If the coolant goes down add more coolant/water mixture until the coolant stays at the same level. Since the motor runs almost hot it sounds like the motor is low on coolant. If not the thermostat is another culprit. Follow the top radiaor hose back to the engine. Where the hose meets metal is the thermostat housing. If the thermostat is good. follow the lower radiator hose to the engine block. This is the water pump. Look for a tiny hole behind the pulley. If there is liquid coming out of the weep hole the water pump is bad. If none of this try a coolant flush as described above.

Posted on Jan 12, 2009

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Replace the thermostat... follow the upper radiator hose to where it meets the motor... you need to drain the radiator fluid (don't have to drain it all) remove the bolts ... not the position of the old thermostat.... remove it ... scrape off the old gasket... replace the thermostat proper side toward the motor... bolt it back up... add radiator fluid to the system... wait for the thermostat to open... top up the fluid and put the rad cap back on.... inspect for any leaks

Robert

Posted on Jan 12, 2009

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When the water runs out of the radiator, it either means that the radiator is cracked, which means that its building steam inside your radiator. building the steam inside your radiator raises the temperature of your engine causing it to overheat and steam up on you. 

Posted on Jan 12, 2009

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You have a head gasket problem which will become more apparent in a short time

Posted on Jan 12, 2009

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Check the coolant level. You might just need a little extra anti-freeze.
Thermostat may need replaced if.................
If bleeding the air out of the system does not work try this. With the truck running check the temp of the coolant lines going to and from the heater core. (about 1-1/4" in diameter hoses that go to your firewall.) As you face the engine the left hose is the inlet hose and the right is the outlet hose. If the inlet hose is warm-hot to touch and the outlet hose is cool then you may have some blockage in the heater core. Now turn your heater fan off or to low speed and check the outlet hose again. If the temp is rising the you still have some flow through the core and may be able to flush the gunk out. I went to the hardware store and purchased a female garden hose replacement end that would fit a hose with a 5/8" ID. Take off the clamp that you would secure the hose with and just use the barb end to insert into your heater core hose. With the car off and the engine cool remove the right outlet hose from the waterpump. Then the left hose can be split at the union fitting that is about half ways to the heater core. Now you can try to flush the core. Insert the hose barb that you have purchased into the right outlet hose and move the left inlet hose away from the engine so that you don't spray water on the block or manifold. Turn the water on and flush the core. You will probably see some grey water come out of the inlet hose. Run till clear. Turn off the water. Remove the hose from the outlet hose and move to the inlet hose. Flush again with the water running in the opposite direction till the water is clear. I had to do this about 3 times till the core was clean. I did use hot water but I don't think that is a must. After you are done flushing replace the hoses and add coolant to the radiator till full. Start the engine and let it idle till the the thermostat opens. You should see the coolant rise and then fall in the radiator neck as the air is bleeding out of the system, replenish the coolant as it goes down. . While the system is bleeding you should be able to feel the outlet hose get warm. If it is you should have heat. Good luck and be careful.

Posted on Jan 12, 2009

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Hi!
Double your coolant volume. And check that gasket is not loose or wide enough as the crank

Posted on Jan 12, 2009

  • Rylee Smith
    Rylee Smith Jan 12, 2009

    Also check your thermostat housing

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There is nothing wrong with head gasket :)

read with patience......

Here is an answer to the original question about the posters heater core. It is plugged. I had the same exact problem. I had flushed out my coolant system several times, but still no real heat coming from the heater. I then finally thought about it and realized the the convential way of flushing out a coolant system does not really flush out the heater core. The problem is that when you flush the coolant system out you normally connect the flushing water to the inlet side of the heater core hose and then backflush the system out through the radiator cap. This works fine for the engine and the radiator, but does not backflush the heater core. But for less than 99 cents and about 15 minutes you can easily backflush your heater core yourself. 

1. What you have to do is get a 5/8 inch female garden hose adapter. This can be purchased at just about any hardware store. Make sure it is the kind that slips inside the garden hose. 

2. Then with the engine cool you need to disconnect the outlet hose of the heater core from the engine. You need to do this at the water pump connection, which should be on the driver's side of the engine. Then insert the garden hose adapter into the end of the hose. 

3. Then disconnect the heater core inlet hose from the engine connection. On my Dakota this is easily done at the splice that is on the passengers side of the engine. This splice is where you normally connect to flush out the coolant system. 

4. Then hook a garden hose up to the outlet hose and turn on the water. Have someone help you turn on and off the water as you flush out the heater core. 

5. You will probably have to flush the core for a good 5 minutes to fully clean it out. Then reconnect your heater hoses as they were and enjoy the heat. 

Try and collect atleast the first 2 gallons of stuff you flush out and dispose of this according to your local laws. After the first 2 gallons all you should get out of your heater core is dirty water. This should be ok to just dump on the ground but make sure first. 

And yes -- top outlet from heater core goes to engine, bottom outlet to water pump.

I used to install a Prestone Flush-n-Fill kit on everything I drove. I got away from that philosophy, and as a result I darn near froze! If you install a kit, do it in the line that goes from the pump to the heater. Then, just clamp the heater hose between the fill connector and the pump to force the water back through the heater, through the engine, and into the bottom of the radiator, and down the drain. ...


This is a solution given by one of the experts in one of the blogs where ppl raise their voice against the same issue.....

 Before that " I WOULD RECCOMEND U TO CHECK ANTI FREEZE LEVEL".......TOO LOW LEVEL MAY RESULT IN THIS AS WELL :)

THANKS.

Posted on Jan 12, 2009

  • taran_2005
    taran_2005 Jan 12, 2009

    YES.................




     THERE IS NOTHING TO LOSE.....THIS IS ONE OF REPLIES FROM RENOWED EXPERTS IN 
    AUTO INDUSTRY...


     HOWEVER, MAKE SURE UR COOLANT LEVEL WLD BE FINE...




     TRY THIS AND I WLD ALSO ASK MY FRD WHO IS WORKING AS AN EXPERT I AUTO INDUSTRY
    TO SUGGEST.




    TAKE CARE AND DO NOT FORGET TO RATE :)

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The defroster could be a few things. Wiring harness, bad heating element, bad switch. If you or a friend have a multimeter, see if power is getting to the defroster. If it is, the heating element (those lines on the window) is bad. If it's not, it's electrical.

Posted on Jan 12, 2009

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  • 233 Answers

This sounds like a bad water pump or thermostat - the thermostat would be an easy fix, however, you may want to have a mechanic check your water pump... if it is not circulating coolant, it will never "push" new, HOT coolant through the heater core.

Posted on Jan 12, 2009

  • Josh Crager
    Josh Crager Jan 12, 2009

    not to mention, this could also cause the engine to overheat and possibly cause engine damage...

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