Welcome To V6Mustang.com!

We are the oldest and largest V6 Mustang forum on the internet. If you have any questions about your V6 Mustang or just want to connect with other V6 Mustang owners around the world, you have found the best place on the internet to do that.

Registering is free and easy! Hope to see you on the forums soon!

Overheat problem

Discussion in '1994-2004 V6 Mustang Tech' started by Dennis.vr, Sep 14, 2014.

  1. Dennis.vr

    Dennis.vr New Member

    Joined:
    Sep 14, 2014
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    I have a 2003 mustang with 3.8 V6 and at times it over heats. I say over heats when it gets to ¾ on the gauge, normally it runs at ½. It has 130,000 miles on it and I replaced the water pump Tstat and radiator fan assy.
    It runs fine and then sometimes it warms up. Yesterday 100 deg outside, AC running and it would be OK and then it would start warming up. I would turn off the AC and no change, but I could turn on the heater and blower fan on hi and cool it down. Then after a few minutes I could turn AC back on and it would be OK for awhile.
    Also sometimes when it was warm the AC would quit working.
    I’m thinking it could be a faulty coolant temp sensor that is working sporadic and causing it to warm up and without the fan blowing causing high pressure in the AC and shutting it down.
    Sooooo what do you guys think?
     
  2. six gun

    six gun Active Member

    Joined:
    Jun 26, 2014
    Messages:
    280
    Likes Received:
    58
    Trophy Points:
    38
    Location:
    South Dakota
    Those coolant, oil and volt gauges are a joke. I imagine yours are no different from my 99 - my coolant temp gauge needle, once it warms up, will sit and stay at exactly one point right below half no matter what. There's been times I've run hot when I seized my tensioner pulley and belt shredded and still had to drive my car to get home, and temp needle never moved above that magical point it always sits at. Anyway..

    Do you know about your digital odometer display being able to read your gauge stats in real time? It will also show your coolant temp in degrees Celsius to show you if you're truly overheating or not.

    Or, could it be either that your thermostat could have possibly been put in backwards? I don't think its able to fit facing the wrong way but still. And do your radiator fans work for sure? As far as the coolant temp sensor, I personally haven't had problems with it before so maybe someone else could shed light there.
     
  3. Dennis.vr

    Dennis.vr New Member

    Joined:
    Sep 14, 2014
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    Thanks for the reply. No, I do not know how to check the gauges thru the odometer. How is that done?
    I was just checking the car after my wife came back from town. The temp gauge was normal. Setting and letting it idle and AC on I was able to get the temp to rise to 3/4 and I confirmed that the fan was working all the time. Also as I said in the first post, I was able to get the AC to act up. When the temp went up to 3/4 the compressor would cycle onand off. When the temp went down the AC work OK.
    Thanks again
     
  4. six gun

    six gun Active Member

    Joined:
    Jun 26, 2014
    Messages:
    280
    Likes Received:
    58
    Trophy Points:
    38
    Location:
    South Dakota
    Well to do the odometer display:

    - with key off, hold the trip odometer reset button down
    - turn key to on position while still holding button
    - after a couple seconds, the odometer will say "test"
    - let go of button, cluster will do a gauge sweep, and from there you can press the button to cycle through its different displays.

    The first few I don't recall, but eventually you'll come to the actual gauge readings. Should come up on Speedo reading first - it will read "ENG" followed by your mph speed. Push button again to switch to km/h. Next is tach reading, then I believe it will come to coolant temp. It will say "DEGC" and your coolant temp. Then more button pushes will lead to fuel, oil, volt readings using a number between 0 and 255.

    So yeah, not that this is info useful for fixing your problem but that diagnostic mode on your odometer display is pretty sweet. In fact I think all models of fords that use that type of green digital display will do that same type thing.
     
    tec_41 likes this.
  5. six gun

    six gun Active Member

    Joined:
    Jun 26, 2014
    Messages:
    280
    Likes Received:
    58
    Trophy Points:
    38
    Location:
    South Dakota
    As far as your ac compressor goes, i thought it was normal for it to cycle on and off anytime it's on anyway?
     
  6. Phil II

    Phil II Cone Destroyer Staff Member

    Joined:
    Sep 19, 2013
    Messages:
    1,442
    Likes Received:
    214
    Trophy Points:
    73
    Location:
    Columbia, South Carolina
    Th a/c compressor should cycle during normal operation.

    I'd check the radiator, and maybe do a coolant flush while replacing the the thermostat. I'm thinking this may help because you're experiencing poor heat exchange yet the heater core makes a difference.

    Also of note: a friend's car experienced a similar over heat episode. Turns out his fan motor was on its last legs.
     
  7. Dennis.vr

    Dennis.vr New Member

    Joined:
    Sep 14, 2014
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    Thanks six gun, that's sweet. I had to go out to the car and try it. I will try to get it to heat up tomorrow and see what temp it says.
    As for the AC cycling, it only does it when the temp gets to 3/4 on the gauge and it blows out hot air. When the temp gets back at 1/2 it works normal.
    Thanks guys, I sure appreciate the help.
     
  8. 6 Shooter

    6 Shooter Well-Known Member

    Joined:
    Jan 4, 2013
    Messages:
    1,347
    Likes Received:
    226
    Trophy Points:
    73
    Location:
    Dallas, TX
    The CCRM is a relay box in the passenger front fender which controls the radiator fan and other things. The Ford parts guy will say that its a frequent failure part. Got me in the past with overheating due to an intermittent fan not coming on when the motor was hot.
     
  9. Dennis.vr

    Dennis.vr New Member

    Joined:
    Sep 14, 2014
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    Thanks 6 shooter,

    I did a little research on the CCRM and it shows a low and high speed relay for the radiator fan. Now I'm wondering if the fan isn't working on high speed, because when I checked it when the temp went up the fan was running. I'm thinking that it was running on low speed when it should have been on high speed.
    Let me know your thoughts. Thanks
     
  10. 6 Shooter

    6 Shooter Well-Known Member

    Joined:
    Jan 4, 2013
    Messages:
    1,347
    Likes Received:
    226
    Trophy Points:
    73
    Location:
    Dallas, TX
    My issue turned out to be an intermittent issue. Sometimes the fan would come on when it should, other times not. When the fan did not come on when it should, the motor would over heat and boil the coolant. All the while, the water pump was working. Those CCRM relays go bad over time. If your car is 8-10 years old, that could be the issue. Ford sells them for over $200. You may be able to get one from an Auto Parts store for a lot less.
     
  11. Markstang

    Markstang Polishing my banhammer Staff Member

    Joined:
    Nov 5, 2012
    Messages:
    1,004
    Likes Received:
    74
    Trophy Points:
    58
    As far as I'm aware, the v6 only uses one fan speed while the GT has two.
     
  12. 6 Shooter

    6 Shooter Well-Known Member

    Joined:
    Jan 4, 2013
    Messages:
    1,347
    Likes Received:
    226
    Trophy Points:
    73
    Location:
    Dallas, TX
    I put some white paint on the end of one of the fan blades then popped the hood when the motor was getting hot to see if the fan was turning. Mine was not. Fixed the issue with a new CCRM.
     
  13. Dennis.vr

    Dennis.vr New Member

    Joined:
    Sep 14, 2014
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    Thanks, your probably right. I check the voltage at the plug for the fan and was getting 14v same as at the battery.
    I did some tests yesterday to check the temps thru the odometer display verses the gauge, here they are;
    101c =213f at 1/2 on gauge
    116c=241f at 3/4 on gauge
    120c=248f at 7/8 on gauge
    I verified that the fan was running at all temps so that tells me that's working OK.
    So that only leaves the Tstat or the radiator, because I can get it to cool down by turning the heater on and blower fan on high.