Engine Running Hot

Discussion in 'Fox 5.0 Mustang Tech' started by deathb4dismount, Aug 2, 2013.

  1. Having a cooling issue. Cooling system is stock as well as the rest of the engine so I dont think it should be running so hot. It runs at the O in the NORMAL range on the temp gauge no matter if I am going 80 or I am sitting in traffic. Today I burped the coolant system and replaced the temp gauge sending unit and it has not changed. Also something weird happened when I replaced the sending unit. I first disconnected positive termy then the sending unit and I had to also disconnect the TFI module in order to remove the sending unit. After I put everything back together and started back up I now get a CEL. Never had one before. Any thoughts on what is going on?
  2. you should always disconnect the negative cable when working on electrical. Don't know why you would disconnect the TFI to get to the coolant temp sending unit for the gauge. It simply comes out with a socket on it.

    Starting with the cooling issue, it could be anything from a

    clogged radiator
    old antifreeze
    air restriction
    collapsed hoses
    bad water pump
    head gasket
    incorrect timing
    bad clutch fan
    bad tensioner
    bad radiator cap
    leak in the system
    Overflow tank leak/cracked or hose clogged

    First thing is to do the free stuff before throwing parts at it. Rent a pressure tester from Autozone and test the coolant system and radiator cap that they hold pressure. Look inside the radiator for signs of corrosion or crude. With the car started up remove the radiator cap and when the stat opens you should see the coolant move across the top indicating flow. If you see bubbles or oil, you have problems. Check for crud blocking the front of the condensor and radiator. Grab the clutch fan, it should spin about 1/2 a turn when cold. If it spins freely, then the clutch is bad. Check for signs of silicone leaking around the hub or on the blades. Also the plastic blades tend to crack. You can buy a cheap tester to see if the coolant needs to be changed but if it has been more than years change it anyway. Same for the hoses as you cannot tell from the outside if they are deteriorating. Check to see if water is coming out of the weep hole on the water pump. Do the hoses feel squishy. Does the upper hose stay hot and the lower one cold? Did you put the thermostat in with the spring facing the motor or the radiator. It faces the motor. Also did you test it before installing to make sure it opens. What temp stat did you use. Too low a temp will make your car run hotter. It should be the stock 192.

    Chances are you still have air in the system. Some times you need to elevate the front of the car to get all the air out of the system, and also burp it a few times.

    DId the car overheat? Does your car blow white smoke or is there oil in the coolant or coolant in the oil?

    When removing and replacing the TFI you need to be careful not to bend or brake the prongs and also grease the backside. Did you move the distributor? If so did you make sure the timing is set on install.

    Run the codes and it will tell you why the CEL is on.
  3. Sorry I didn't give more info last night, I posted it after a few Johnnie Walkers. CEL is a result of me being a moron. All set now. I had to unplug TFI in order to remove temp gauge sending unit, the way the TFI was angled I could only get a quarter turn with the socket. Unplugging it just made it easier. Dizzy was not removed. I havent changed tstat, and not sure if previous owner had. Water pump and goose neck look new so it is possible. Have a new tstat in case I need to replace it.

    Car has never overheated and does not blow white smoke or have any blue smoke from exhaust and is not burning oil. Water pump is working, fluid is running through hoses, top one is hot have not checked bottom one yet. I have no leaks, oil or coolant. (I know I cant believe it either, I checked everything numerous times).

    Coolant is probably old so I am going start by flushing the system and go from there.
  4. First make sure your cap is good.

    If that does work and the radiator is stock as in original, i would replace it with a chain store 3 row instead of flushing the old one. You don't want to contaminate new coolant by putting it in a 20 year old radiator. At $10 a jug the cost of antifreeze adds up.

    Just do the thermostat too at the same time and replace any questionable hoses.
    Messing with the coolant system gets old real quick, i prefer to hit it all at once.
  5. Ok so I am thinking the gauge is just totally jacked up. It only took about 3 minutes of idling and reving to about 2500 for the gauge to read 220. It then took another 5 minutes for tstat to open. Once the tstat opens I have flow through both top and bottom hoses. Fan is not cracked, clutch is good and is working properly. I would think that once the cooling system is in operation the temp gauge would read cooler, but this is not the case. I am going to replace the tstat today for piece of mind. And then check everything again. If I get the same result I will be pretty confident that the 20 year old gauge is FUBAR. My only question is will a faulty ECT also cause a bad reading? I would rather spend 30 bucks and replace that then buy an aftermarket gauge.
  6. ECT has nothing to do with your coolant gauge. you coolant sending unit does. if you suspect your gauge is on the fritz then swing by autozone and pick up another sending unit. they are fairly cheap.
  7. Thanks, I wasn't sure if ECT had anything to do with gauge, now I know. Already replaced sending unit and that has not helped.
  8. at this point I would say that if you in fact dont have a bad tstat try burping the system one last time. jack up the front of the vehicle so that the radiator cap is at the highest point of the engine. start the car and wait for the tstat to open. any remaining air at this point has no choice but to move towards the open radiator cap.
    If you still have probs after this replace the radiator cap. if its venting out steam then your car will never cool. If that doesnt solve the problem you likely have poor flow through your radiator. buy a new one and be done.
    Also check the ground strap from your heads to the firewall. I was chasing an overheating issue that was nothing more than a bad ground overloading my temp gauge.
  9. Here is how to test the temp gauge......ground the wire from the temperature sending unit at the left front of the intake manifold and turn the ignition to key on. If the temperature gauge moves, the sending unit is failed. If memory serves me right, it should go all the way to 270. If grounding the wire of the sending until does not affect the gauge reading, the wire is broken between the sending unit and gauge or the gauge its self is failed. Do not ground the wire for a long period of time as the low resistance could burn up the gauge. If there is a short in the wire that would also cause damage to the gauge.
  10. So my anxiety got the better of me and I lost almost a week and a half of fun. Installed this today and after a 30 minute cruise and some 1st through 2nd rips all is well. Shouldn't have trusted the old stock gauge, it would have been almost pegged if it was hooked up. Temporary mounting location for the gauge, I am going to mount 3 under the radio.

    Just happy that I don't have to make any immediate changes to the coolant system.

  11. Is that a pic of the real temperature?
    If so I wouldn't be so thrilled with 215+ degrees.

    I had mine setup to run 180 pretty much regardless of the weather. Some prefer 190, but close to 220 would make me nervous.
  12. agreed

  13. uh... that ain't good IMO. If you have a 192 stat your car shouldn't be at 220. Maybe 5-10 over but not 20 degrees. Did you see the gauge go up to 200 or so and then drop when the stat opened or did it stay up.
  14. Damn. It dropped a little when stat opened then went up to 210, guess I am going to have to throw some money on maintenance issues. Drove the car today and when I shut it off the fuel pump stayed on. I think that just means a bad relay, correct?

    As far as cooling system I am going to get a new radiator next week when I get back from vacation, but I am not sure of I should I go electric fan?
  15. if you arent cooling adequately with the clutch fan an e-fan isnt going to be a magic fix.
    put in the radiator and fill with water. purge the system until you have all the air out. once you verify you have no leaks and that the new radiator is doing its job drain enough water to add the proper amount if coolant.
  16. dunno if this has already been said

    overheating when idling or low speed- fan or water pump most likely
    overheating at higher or highway speed- airflow problem or radiator

    Did you ever pressure test the system? You could have a pin leak in the radiator, or a hose.
  17. This.

    It doesn't heat up very fast, that seems very normal. It is once it gets up to that tstat opening temp that it gets hot and doesnt seem to come down at all.

    Thanks for helping btw, I am still a beginer at best with this stuff. You think you know a few things till something goes wrong
  18. What's cooler than being cool? Well I am not sure, but this is much nicer.


    It was a combo of old radiator, crappy tstat, and old coolant. Installed new SVE aluminum radiator and motorcraft 180 tstat today. Man I forgot how much of a PITA the tstat install is. It took me 2 hours because I had to do twice. The first time the tstat slipped down and when I started it up...water works. Went out and bought an adhesive backed gasket and it made it much easier. Luckily the bypass hose was fairly new and didn't give me too much trouble. The SVE radiator took only about 30 minutes. It was very easy and needed no modification of the brackets or anything, direct drop in. I have to give LMR kudos for that piece.

    This is the tstat that was in the car. It says it's 160, but I have never seen one like this before. I knew fluid was flowing before, but I dropped it into some boiling water just to be sure. It took about a minute and a half to open. May have been the main culprit all along but an upgraded radiator and fresh coolant can't hurt either.

    I just want to thank you guys for all the help. If it wasn't for you I would still be driving around with engine temps around 220.
    [email protected] likes this.
  19. I prefer that brand, it's a mr gaskets. 160 is too low though, especially with an old radiator, it will basically run wide open all the time and the coolant never has time to cool.
  20. quick tip when replacing a t-stat...use some blue or black Permatex to keep the gasket and t stat in place while you drop on the waterneck