Question about Toyota Corolla

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The car overheats after I drive it for about 5 miles. I have aleady change the radiator , termostate. the watter pump is not leaking and is not spittting watter through the muffler. What do you think could be the problem?

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  • janet_j237 Jul 18, 2009

    Thank you very much for your sugestions.I have a question in refernce to how to know when the termostate is open. You do sugest I remove the cap off when radiator is cold ,and when the termostate opens to check for bubbles. O.K. I did and I see no bubbles in the watter, I check the oil level and is just right, it has a new oil change recently, I do that every 3,000 miles. I noticed today that it heats up even when I drive it without the air conditioning running. Some mecanic put in the scope machine and he said everything is O.K. I hope youcan help me after this information.


  • janet_j237 Jul 18, 2009

    By the way I just remember that the radiator wis new and it has life time waranty.



  • janet_j237 Jul 18, 2009

    I forgot to ask: how do you bled the radiator?


  • janet_j237 Jul 19, 2009

    Hello there:

    Thank you so much for all your imput and advice> Both of the fans are working, the oil level is just fine, when I turned the engine and reached the right temperature I observed the water in the radiator but I do not see water passing through it , what I see is watter rasing a little bit and causing a little overflowing and big bubbles comming to the surface of the radiator, some times one or two some times a bunch of them. I also see like tiny bobbles like foam mixed withthe big bubbles. I am realy worry about this problem.

    The compresor of the air conditioning sits in the left side of the radiator and is not stopping the flow of air to the compresor. I do not know if the compresor and the condensor are the same thing. The two funs are working o.k.

    Please advice,


  • janet_j237 Jul 19, 2009

    Hello again:

    I forgott to mention that my Toyota is an 1998 Corolla Le.

    Thanks again

  • janet_j237 Jul 20, 2009

    I thank you so much for all the trouble I am giveng yo. I will have the shop that place the termostate recheck if it was place right. I will take your advice to him. Thanks again for now and I will talk to you later.



  • janet_j237 Jul 20, 2009

    Thanks a buch and I greatly appreciate all of your time and patience.




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Four main things I can think of off the bat.

1.The radiator you installed was not new, and is rebuilt. The shop that did this merely cleaned it up a little, and spray painted Black on the outside. I have had complaints from people, and had one radiator shop try this on me. Yes, his face turned really red when I calmly showed him the crud, still down inside the radiator with a flashlight, and advised he try again. Then I told him I am a professional mechanic, and if he wanted to step out of the way, I could do the job. (I can)

2.When the thermostat was installed, the coolant system wasn't bleed of air. Air becomes trapped when a thermostat is installed. There may be a drain valve located on the bottom of the thermostat housing.
This is opened until coolant starts to come out, and no air bubbles are present. With my old Corvettes I drill a small hole, (1/8th inch), in the thermostat. The center of the thermostat is a valve. It raises up off the center making an opening. Where the round part of this valve meets the outside part, (Inner hole), of the thermostat, I drill this hole. This bleeder hole then lets any trapped air escape.

3.I appreciate your skill in diagnosing your problem. Did you check the oil level? Maybe you do have a blown head gasket, but it isn't bad enough to spit water out of the tail pipe. (Muffler)
Radiator cap removed when the engine is cold. Warm the car up, and when the thermostat opens, observe the coolant. Are there an abnormal amount of bubbles present? Some bubbling is normal as the coolant passes through. A steady stream of bubbles is not.

4.Bad thermostat. Even if it's brand new, lemons are made. The thermostat is not opening, or isn't opening as far as it should.

Posted on Jul 17, 2009

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  • joecoolvette
    joecoolvette Jul 17, 2009

    Sorry I had a typo, "2.When the thermostat was installed, the coolant system wasn't bleed of air.
    I meant "When the thermostat was installed, the coolant system wasn't BLED of air."

    In Number 3., I meant to go further. "Did you check the oil level?"
    Meaning, has the oil level risen. An abnormally overfull condition, would suggest coolant leaking past a blown head gasket, and getting into the oil pan.

  • joecoolvette
    joecoolvette Jul 18, 2009

    What I meant in reference to checking for bubbles in the coolant, by viewing through the radiator cap opening of the radiator,

    1.Remove the radiator cap when the engine is cold. If the engine is hot, and you remove the radiator cap, you stand the chance of hot scalding coolant spraying up out of the radiator. (Radiator cap opening)
    Let the car run until it reaches operating temperature. Observe the temperature gauge often, as it sounds like your car is heating up quick. You do not want the car to overheat.

    When the temperature gauge indicates the engine is at operating temperature, (Gauge may just have a green zone, or actual numbers. Below the Red area is the normal operating temperature for most cars), observe the coolant flowing past the radiator cap opening. Not trying to insult you in any way, but Do Not have your face very close to this opening. There may be a trapped air bubble, and air could push hot coolant up, and out! Watch the coolant flowing past the radiator opening. Does it have a stream of bubbles issuing up? Not an occasional bubble as the coolant flows by, but a small steady stream.
    If there is a small steady stream, you have a blown head gasket. (Gasket has disintegrated in-between the cylinders, allowing the hot gases from one or more cylinders, to enter the water jacket, and coolant)

    IF, NO coolant streams by the radiator cap opening, and the temperature gauge indicates the engine is at Normal temperature, or above, then you have a bad thermostat.

    Sorry if I wasn't very clear about this.

    Hmmm, I don't believe you stated before, "I noticed today that it heats up even when I drive it without the air conditioning running"

    This changes things. The air conditioning condenser, (Aluminum radiator looking object in front of the radiator), could be plugged with insects, dirt, grass, and other foreign debris. Many fins of this condenser could be bent over, which will drop the ability of the condenser to work, tremendously.
    Air cannot flow through bent fins.

    Also an air conditioner puts a heavy strain on the cooling performance of a car's radiator.
    For one, the condenser sits in front of the radiator, and blocks a lot of air from reaching the radiator.
    For two, when you are in a lot of stop and go traffic, running an air conditioner, and if it's hot outside, (It is), the car will overheat very easily. There isn't enough air reaching the radiator.

    Another thing I should have mentioned:
    Your Toyota Corolla should have an electric fan, or two, for the radiator. There is a temperature sensor switch (Electrical) that should be located in your thermostat housing. If it is bad the fan/s won't come on. There is another sensor also.
    To test:
    When you are running the car to check to see if there are air bubbles present, and also to see if coolant is flowing past the radiator cap, watch the temperature gauge to see when it reaches operating temperature. If the gauge goes past the Normal operating temperature, (Reaches the Red area), the fans should kick on.

    If not, the fan sensor switches should be bypassed, and see if the fan/s themselves are operational.
    If the fans are operational, then your problem is one of those two fan sensor switches.

    Bleed air out of the radiator? I need to know if what year of Toyota Corolla this is. This way I can look up to see if there is a bleeder valve, located on the bottom of your thermostat housing.

  • joecoolvette
    joecoolvette Jul 19, 2009

    From your recent description it sounds like a bad thermostat. May I ask who installed it? That is, was it you or a repair shop? The thermostat housing is located behind the alternator, and the oil filter must be removed to access it. (The oil filter sits sideways, and removing it does make a bit of a mess)

    If a repair shop replaced it I'm starting to doubt their integrity. Doubt as to whether they really replaced it or not. However, it could just be a bad thermostat that came from the factory.

    Upon further observation, of the particular style of thermostat that is made for a 1998 Toyota Corolla, (Limited Edition or otherwise), the thermostat is made with a 'Jiggle Valve'. This small hole, and valve are located near the outside ring of the thermostat itself. In the outside ring of the thermostat there is a small hole. In this hole is a valve. This valve resembles a small 'Dumbell' in shape. Just like a dumbell that a body builder works out with. This is the Jiggle Valve.

    This Jiggle Valve MUST be placed in the correct position, when the thermostat is installed.
    (Also thermostat installation. On the top of the thermostat, will be stated the temperature that the thermostat opens. What the temperature of the water will reach, then the thermostat will start to open. It's 82 Centigrade. On the top will be stamped 82 C. The top of the thermostat must face you when installing it. The side that has the spring goes down in the thermostat housing itself)

    The Jiggle Valve will be placed 10 degrees to the left of the stud bolt, or 10 degrees to the right of it.
    There are two stud bolts that hold the top of the thermostat housing in place. (The top of the thermostat housing is the part that has the Lower radiator hose attached to it)
    The thermostat housing top slips over these studs, and then washers, and nuts are put on the studs.
    You are supposed to use soapy water on the rubber O-ring, when installing the thermostat.
    (The O-ring goes around the thermostat itself)

    The Jiggle Valve takes the place of having to open a Bleeder Valve. It's supposed to release any trapped air. If this Jiggle Valve wasn't placed in the correct place, (See above), it cannot open.
    Should you, or a friend, have installed this thermostat, and you didn't know about the correct way to place the thermostat in the housing, you're going to have to remove the thermostat, and inspect it.
    Inspect it to see if it was placed in the correct position, and see if it's still in good shape if it was not.

    Car COLD! NEVER work on your coolant system when the car is hot. Drain the coolant into a suitable container. (If it's drained on the ground, animals can drink it, and be poisoned. A very nasty way to go too, I might add! I happen to love animals)
    You can reuse this coolant if you keep it clean, so after draining cover it, and move it to a safe place.
    Place another container underneath where the oil filter is. Loosen the oil filter, and remove. Now remove the nuts, and washers off of the thermostat housing studs. Remove the thermostat housing.

    The condenser for your air conditioning sits in front of your radiator. It looks just like your radiator, but it is smaller. It's hard to see as there is a radiator support that sits on top of your radiator. ( Flat piece of metal that is wider than the radiator) It's about the thickness of a single digit of your finger, while the radiator is about the thickness of a whole finger.




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