Overheating Issue... Please Help!

Discussion in 'SN95 4.6L Mustang Tech' started by blaxican27, Aug 7, 2014.

  1. 2000 Mustang GT with an 03 Gt motor.....I am having annoying overheating issues. Currently I have new fan, water pump, thermostat, and CCRM and have taken it to get a radiator flush. I know my fans are turning on for sure. It is mainly overheating when I am stuck in traffic for a few minutes. Once I start to drive and pick up speed it cools back down but as soon as I exit the highway or get stuck in more traffic for another few minutes it starts to overheat again. There is no oil in the coolant nor coolant in the oil. At this point any and all suggestions are very much appreciated.
  2. What temp degree thermostat did you get? And what temp is the fan set to turn on and off? And what was the reasons behind changing all those parts for? Where you having this problem before you changed all those parts?
  3. It all started with the car overheating. The original fan weas not turning on so I replaced it. Lasted a couple of days then started overheating again but only with the A/C on. if i turned the a/c off it was fine. That lasted a couple of weeks and then it started overheating when stuck in real bad traffic. When i replaced the fan i replaced the thermostat as well. Water pump was under warranty so i went ahead and replaced it again. Still kept overheating so i looked into replacing the CCRM because on one of those days it overheated i noticed my fans were not turning on again. At this point i know for a fact the fans are turning on and all the other items listed above are new. I did the radiator flush just to make sure there was not a clog somewhere in the radiator or lines. The fan and thermostat are basically aftermarket. oem replacements.
    #3 blaxican27, Aug 7, 2014
    Last edited: Aug 7, 2014
  4. But do you know the degree of thermostat you replaced with? And the temp the fan is triggered to come on? And when you say overheating, where you at temp wise when it is in your words overheating? Just want to know those few questions before I go forward, thanks.
  5. I am not sure of the temp of the thermostat nor the temp to trigger the fans. I have never adjusted the temp for the fans so I guess whatever stock is. For the thermostat I just purchased a basic replacement at the auto parts store. When I say overheating I mean anything and everything pass halfway. On a few occasions it got so hot it leaked out all the antifreeze through the radiator cap.
  6. DOUBLE check the motor grounding strap from the left hand motor mount to the frame rails. Ensure the mounting points are clean and tight.

    Have the cats been inspected for blockage?

    FWIIW, if the motor never over heats at freeway speeds, that all but proves that the over heating is related to air flow over the radiator. Why? Because the PCM turns off the fan when the car's speed is above 45 MPH. So at highway speeds the fan isn't used at all.

    Confirm that the cooling fan has been tested to work on BOTH speeds. Confirm that the fan spins freely with no binding or bearing drag.

    Confirm that the fan is spinning in the correct direction and is actually moving air. This should be obvious.

    Confirm that the outside of the radiator is clean and that all air dams and fan shrouds are in place.
    #6 wmburns, Aug 8, 2014
    Last edited: Aug 8, 2014
  7. I will check the ground straps but can you explain how that may affect the overheating? I have an off-road H-pipe so i do not have cats. The fans for sure work on high since they turn on as soon as I turn on the a/c but i cant say if it turns on low speed or not. The fan does spin freely, in the right direction, and moving air. Which air dams are you referring to?
  8. What Iwould do is wait till you are in the position that causes the overheating, ie at a stop light or traffic. Then I would jump out real quick to pop the hood and see with my very eyes that the fan is running at the time overheating is happening. You may say they are working, but are they working at the right time.

  9. That is what i did a couple of weeks ago which is when i changed the CCRM. I had already replaced the fan so i knew that was new so my next option was to replace the CCRM which i did and since then the fan would turn on when turning the a/c but i have not checked like you said, when the overheating is actually happening.
  10. ^^^^^This is NOT correct and may be the key to solving your problem.

    For the GT when the AC is on, the fan runs on low speed. That's correct. Low speed.

    If the motor's temperature continues to rise, then the fan switches to high speed. So it would be normal for the fan speed to cycle between low and high speed in heavy stop/go traffic with the AC on.

    So IMO it's likely that the fan is NOT actually working on high speed.

    Note, some model year V6's uses a single speed fan. Are you absolutely certain that the correct fan for the application has been used? Because if the V6 fan is used in a V8 application, the symptoms you are seeing would be expected.
    #10 wmburns, Aug 8, 2014
    Last edited: Aug 8, 2014

  11. By no means am i an expert nor will act like i am one. I have however been told and read on multiple threads that the fan works on high with the a/c on since the a/c does force your engine more when its on. that being said it makes more sense to me that it works on high than low. as far as if i have a V6 fan or a V8 fan is a good question. i am not sure. my cousin ordered the fan for me since he is a mechanic and gets retail price. that being said i used his judgment and am assuming he did get the right fan.

  12. I called the dealer to confirm if the fans were different or not and they are different. the mounting points are different and the fan i have mounted perfectly fine with my old fan so i am sure i have the right fan.
  13. There's some great information on the forums. But sometimes they are wrong.

    Other times the posts are correct for certain model year and engine combinations. Something that may be true in the past may not be true in the future. Take for example all of the threads on "how to adjust the TPS". TPS adjustment does not apply to the 96+ model year. But yet the forums are full of PPL saying to adjust the TPS to resolve idle issues.

    As to which makes more sense to run the fan on HS or LS during AC operation, to me it makes more sense to run on LS. Why? Consider that if the fan were forced to HS, then there's no option/adjustment available should conditions not require HS operation.

    Whereas if the fan runs on LS and cycles to HS when needed, this has the following advantages.
    • Less noise
    • Uses less power
    • Too much air flow could cause the AC suction pressure to drop too low causing the AC to short cycle.
    • Better control of the motor's temperature.
    For further proof, a review of the Ford Factory wiring diagrams is needed. There are circuits that are specifically designed to force the fan into HS mode when the AC head pressure rises above a certain point. Why would Ford design in such an unnecessary circuit if the fan were already in HS mode?

    If you are interested in seeing the wiring diagrams for yourself I may be able to help. PM if interested.

    Finally. Consider that your car is over heating. By any measure you have already replaced a TON of parts with no solution. In cases like this, I usually advise people to stop and back up. Recheck your work. Finally see Occam's razor before starting to look for stranger/less likely possible causes.


    I try to help people by as much as possible providing solid no BS technical advice (3,129+ posts). I often research using the Ford service manuals before responding. I'm going to drop off this thread as it seems that my input is not helping. Please be so kind as to update what the final solution is so that others can benefit from your experience.
    #13 wmburns, Aug 9, 2014
    Last edited: Aug 9, 2014
  14. I'd listen to wmburns. He has a wealth of knowledge.
    blaxican27 likes this.

  15. :stupid: wmburns really knows his stuff when it comes to these Mustangs. He is not a member of this forum that would write anything to just get noticed or bump his post count, we all got better things to do than be a bother to the rest. Take his advice and run with it. He will not mis-lead you. And you got to remember we are on a forum, and visual / hands on diagnosis is impossible. So he can only give you advice based on your input in this thread.
    blaxican27 likes this.

  16. By no means am i trying to discredit your advice or input. At this point i will take any and all information since i have exhausted all the options i am aware of. My car is currently at the dealership. I decided to pay and have them check the car out and let me know exactly what my problem is. I will update the post as soon as i hear anything back from the dealer, that is if they are able to help me resolve my issue.
  17. I just received a call from the dealer and what they told me is that my fan is running too slow and the radiator is showing signs of rust due to lack of coolant (which I am sure is from the overheating). They recommend i change the radiator, upper and lower hoses, thermostat, and upper intake and have a flush done. What do you guys suggest? i just had a flush done about two months ago and replaced the thermostat a couple weeks ago. i am thinking i will do another flush, replace the theromstat for peace of mind and and have another flush for the time being. i dont have the money to do the radiator and upper intake since i just got married two weeks ago. still trying to recover from that.
  18. Upper intake? Unless it is leaking, run from that dealer. They are trying to take your money.

    If the fan isn't working properly you need to diagnose why. It's in this thread what you should do to determine that.
  19. Has the motor actually overheated since the last round of repairs were completed? My definition of overheating is the dash temperature gauge solidly in the red and coolant boiling out.

    Consider that if your definition of over heating is anything above half way on the dash temperature gauge, then there may not be anything wrong that requires immediate fixing (other than your definition of over heating). It would be normal for the motor's temperature to vary over a range especially if the radiator is marginal or it's very hot outside. The key questions is does the motor's temperature continue to climb or stabilize some where short of the red zone?

    Has the motor's temperature been measured with an infrared scanner?

    Your were also given the suggestion to check the motor's grounding strap. Was this done? Have you completed a through review of the battery and charging system? What is the voltage at the battery when the HS fan is running?

    Why is all that important? Consider the following scenario. If alternator isn't able to keep up with the car's electrical load, what happens if this is true? Voltage at the battery drops.

    What happens when the voltage drops?....... One effect is that electric motors run slower (get where this is going?).

    Here's the kicker. The dash temperature gauge is driven by voltage difference from a normal reference voltage. So what happens when the voltage supplied to the ECT sensor is low? The dash gauge will read HIGH.

    If this were my car, I would ensure that the battery, battery cables, and charging system were in tip top shape. No corners cut as there is a possibility that your current symptoms could be related to a charging system problem.

    Today's cars simply will not run right without a strong battery and charging system.

    Then I use an infrared temperature scanner to find out what the motor's temperature at the T-stat housing really is. THEN if the motor's temperature didn't CONTINUE to rise, I would just drive the car until a more convenient time to do repairs came around.

    The dealer may have the correct diagnosis. But there's no way for us out in Internet land to know for sure without the details. But you obviously have doubts. I personally would be upset about all the other repairs done without a fix. I too would have questions about how could a new fan be running too slow.

    Bottom line. In order to make a solid diagnosis with the RIGHT repair, accurate information is needed. This means tests and following the results. This is a process.

    Sappy saying for the day: There is no elevator to success. You have to take the steps.
    #19 wmburns, Aug 11, 2014
    Last edited: Aug 11, 2014
  20. I do refer to overheating when my needles moves anything pass at least the 3/4 area. However yes it has overheated to the point to where the needle was in the red and it boiled over and antifreeze was all on the floor. My battery terminals were getting loose so i did replace those the night before i took it to the dealer. the day i took it to the dealer the needle reached red but did not boil over. i will check the ground when i get home tonight. i will even take it as far as taking my batter to get checked at autozone. Is thjere a replacement fan that is just as good as the OEM or close enough? it hurts me to pay 400 for an OEM fan.