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  1. #1

    Default Overheating issue in 2002 Chevy Silverado 1500 5.3 liter 4x4

    Been having this issue since last summer. I replaced thermostat 3 times (thinking a faulty one), fan does come on, checked for leaks with dye and UV light (only place I saw dye is out of overflow), did a chemical flush today...still no change. Only an issue when it gets over 75...then temp rises...I turn on heat to bring it down to normal and have to run with heat on. Not fun when it is heat index of over 100 out! Suggestions on what to try next?

    Sorry...didn't state what vehicle...2002 Chevy Silverado 1500 5.3 liter 4x4

  2. #2

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    Just a few items to check, since it overheats at high speed/high rpm the fan shouldnt be affecting things.
    Do you have a larger than stock bumper or a winch blocking airflow in the front?
    Is the radiator itself flowing coolant properly (this is suspect since turning on the heater helps the situation).
    Is the water pump flowing properly?
    You dont by any chance have larger than stock tires with factory gearing do you? This could be contributing to the problem.
    Has the cooling system been properly bled of all air, preferably with a vacume bleeder

  3. #3

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    Quote Originally Posted by tbplus10 View Post
    Just a few items to check, since it overheats at high speed/high rpm the fan shouldnt be affecting things.
    Do you have a larger than stock bumper or a winch blocking airflow in the front?
    No
    Quote Originally Posted by tbplus10 View Post
    Is the radiator itself flowing coolant properly (this is suspect since turning on the heater helps the situation).
    How do I check that?
    Quote Originally Posted by tbplus10 View Post
    Is the water pump flowing properly?
    How do I check that?
    Quote Originally Posted by tbplus10 View Post
    You dont by any chance have larger than stock tires with factory gearing do you? This could be contributing to the problem.
    no
    Quote Originally Posted by tbplus10 View Post
    Has the cooling system been properly bled of all air, preferably with a vacume bleeder
    No...how do I do that?

  4. #4

    Default

    Bleeding the system can be done by going to your local Auto Zone or Napa and seeing if they have a radiator pressure check/Bleeder kit for loan or rent.
    Follow the normally included instructions.
    If there arent any included instructions the kit contains different caps to put on the radiator and or resevoir then you draw a vacume which should pull out any air in the system. Sometimes its easier if you park the vehicle with the front end raised a little and make sure you have the heater turned on to allow flow through the system.
    Radiator and water pump flow will probably need to be checked by a shop that has proper equipment. Many skilled mechanics can check the flow by pulling the cap and watching the water at idle but this isnt a tried and true method and can at times lead to mis diagnosys.

  5. #5

    Default

    Thank you! I will try bleeding the system first and take it from there.

  6. #6
    Legend

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    Default

    Quote Originally Posted by Willow View Post
    Thank you! I will try bleeding the system first and take it from there.

    the proceedure to purge air from the coolant system with these vehicles is to remove the coolant pressure cap at the plastic coolant fill container when the engine is cold. the start engine and continue to run engine until it is at normal operating temp. then increase RPM to 2000 and hold for about 30 seconds. repeat a few times. if you had air in the system the coolant level will drop.

    the other reason you may have overheating during warm/hot weather is a defective coolant pressure cap. if you find when it over heats the coolant hoses are not hard/pressure in them then this is what happens. reason is when NOT under pressure the coolant will boil. when that happens the water pump cannot pump air bubbles and then the over heating.

    if you lived in a very high elevation this is more so an issue that the coolant system must be under pressure. since the lower the pressure the lower the temp that the coolant will boil.

    now another thing that causes air bubbles would be exhaust gases entering the coolant system . that would be a bad day.

  7. #7
    Master Mechanic BurbanMan's Avatar
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    Dolores, CO
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    I was always told by the old schoolers that if you remove the radiator cap and start it. If the head gasket is popped, the coolant will flow out even when the thermostat is open
    Chuckie!!!


  8. #8

    Default

    Sometimes the coolant will flow out when you pop the cap on newer cooling systems, head gasket intact, due to the pressure in the system equaling out with the ambient air pressure...
    See The USA In A Chevrolet,
    Or Buy A Ford And Stay At Home!!


  9. #9
    Legend

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    Quote Originally Posted by BurbanMan View Post
    I was always told by the old schoolers that if you remove the radiator cap and start it. If the head gasket is popped, the coolant will flow out even when the thermostat is open
    if you have a head gasket leaking into the coolant to check you would open the pressure cap . then start the cold engine and run until hot rev engine a few times. if you see air/gas bubbles then it is a good chance you have a leak in the head gasket .

  10. #10

    Default

    Update- I had stopped at the body shop a couple weeks ago to let my body guy know it would be longer before I brought him back for his scoops and tiny rust spot repair and tail light covers and he asked if I was still having the issue. Yup. He asked me to pop hood. Said he had same issue recently with his truck and thought about mine. He was on the road towing when it became a major issue. Said he decided to do some tinkering and see if he couldn't improve it till he got home. He checked the outside of radiator for blockage- looked clean. Then he took off his fan shroud and got a real good look...right behind his fan was a circle of lint, bugs, etc. He was able to pressure wash and air spray it out and it fixed it. He had me pull Brutus in and did the same with him. I did not realize when I cleaned off at car wash- I was actually cleaning the ac condenser. ...thought that was front of radiator. Well...he could not get it unblocked....and found a tiny bit of seepage on radiator top corner. He said I could pull it out and clean it and use liquid metal to repair, but he would suggest replacing. I agreed- especially when I found out it was the original radiator. I went ahead and used the bar's first and ran it through (bit better- but not much). Then next day I had son replace radiator. He has run at normal temp since, even in high heat and getting on it (his power has improved too). I am going to take him back in for a check to see if exhaust still leaking in so I know, but since no issues with him running now- will just let it ride.

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