Engine 93 LX temp fluctuating pretty wildly

Discussion in '2.3L (N/A & Turbo) Tech' started by Tavis, Jan 11, 2013.


  1. Tavis

    Tavis New Member

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    I have a 93 LX 2.3L hatchback. It currently has 196k miles on it. I let my GF borrow it for about a year. I recently got it back. Now I am noticing that the temperature gauge is fluctuating pretty wildly. Before, it would hardly ever go above the second mark above 130*F. Usually it would stay in between the two marks above 130*F (sorry, I don't know the increments).

    These days, it is anywhere from two marks above 130*F to two marks below the red zone. I can drive the car and watch the temp hand go up and down. When I'm driving down the road, the temp hand goes up. When I let off the gas, it goes down slightly. Other times, I can idle and it goes up. It is hard to predict.

    I recall a few weeks ago, I got stuck in traffic due to a wreck. The car was idling for at least an hour and I had driven it probably <10mi before encountering traffic. The temp gauge would slowly go up until it hit a little above mid-way and the fan would turn on. The fan cut off after a minute, temp slowly going back down, then temp goes back up, three minutes would pass, fan would come back on.

    I told my dad about this. He replaced the thermostat and both temp sending units. My dad thinks it is fine, but it has never done this before, and I have much experience driving that car. The temp has always been pretty low, except on the hotter days of summer. I don't see how the car will NOT overheat this summer.

    I do know that I accidentally put a lot of antifreeze in the radiator and basically didn't put any water in after (I didn't know any better at the time). It wasn't a full tank of antifreeze - maybe half a gallon. I'm told that's fine because there is some antifreeze/water mixture in the block.

    Could it need more water and less antifreeze? Or does it need a new water pump?
    I'm mostly concerned about it overheating in the summer. Note: I am in NC with a mostly mild winter so far.
  2. 91TwighlightGT

    91TwighlightGT Active Member

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    Here is what I would do if it was my car.

    First, I would pressure test the system and check for leaks or loss of pressure. Test the radiator cap. Make sure your hoses are in good shape and not collapsing, make sure the water pump isn't leaking, radiator, etc. You said the thermostat and temp sensors are new, but if they weren't I would replace them at this point.

    Second, I would flush the cooling system out completely. If there are a lot of original parts on the car, then I would also runs some of the flush additive to help clean out any scum that has developed over the years. Flush that out as directed, then refill with the proper mixture of anti-freeze.

    Run the car and allow it to get to operating temperature. Make sure the fan is working. Make sure the fan shroud is in place and unbroken, as well as the plastic air dam under the bumper. Recheck for any leaks.

    Last, if the problem still persists, I would run get an infrared temperature tester and check the heat readings with that. It is possible that you have simply a bad gauge, but good cooling system maintenance is always a good idea. The gauge can be replaced if it is bad, of course you would also want to check the wiring and any grounds as well.
  3. Tavis

    Tavis New Member

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    Thanks for your response.

    For the hoses, my dad would've noticed any problems with that, or if it was leaking. I have never noticed it leaking, other than when I put some water/antifreeze in the overflow reservoir.
    I think the next thing I'm going to try is a new water pump. Then if it still happens, I'll try flushing it out.

    Would the gauge still be bad if it shows the temp going up and down and shows me the spot I've noticed before when the fan kicks in during the summer?
  4. jcgafford

    jcgafford Well-Known Member

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    not even a well seasoned mechanic can look at hoses and guarantee they are in good shape. if they are originals they are 20 years old. follow the advice given unless you want to throw cash at a problem without knowing what the problem actually is. the pressure tester is a free loaner at autozone and takes less than 5 minutes to check, you can even do it at autozone and not have to give a deposit on it. antifreeze and flush is less than 30 bucks. busting off 20 year old studs trying to get a water pump off that might not even be the problem is going to cost you.
  5. Tavis

    Tavis New Member

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    I'm pretty certain the hoses have been replaced within a few years and the water pump was only ~$35 for a new one.
    Thanks for the tip on the pressure tester. I'll do that.
    There's not going to be any broken studs as I'm taking it to either my father or a reputable repair shop.
  6. Mr67Stang

    Mr67Stang Active Member

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    Your in NC? Me too and last weekend was beautiful! Anyway, definately look at the plastic airdam directly below the radiator support. For some weird reason those flimsy things are required for a Fox Mustang to properly cool. I doubt you have a waterpump problem because they will either leak from the weap hole on the bottom or if the impeller is broken or rotted away (I've seen that) it won't cool at all. Your symptoms are more inline with needing a good flush and or the electric fan switch being flukey. If your close to Raeford, NC, I would be happy to look at it with you if you want. Wee can even temporarily install an aftermarket temp guage and eliminate or pinpoint your guage/temp sender as the problem.
  7. 91TwighlightGT

    91TwighlightGT Active Member

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    The air dam creates an area of low pressure behind the radiator, which causes the air to travel up and through the radiator. If the air dam is missing, then there is nothing to force the air into the radiator, and you overheat.
  8. Tavis

    Tavis New Member

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    Yes, I'm in NC. I'm in Lexington, NC.

    As an update, I took it to a mechanic a few weeks ago for this problem and some others and they kept telling me they let it run for an hour or so and the temp stayed low. I asked them to flush the radiator and they were supposed to do so. That seemed to help the temps a little, but not much. However, on my way home today from work, this is the temperature of my car after sitting maybe 10min in the Arby's drive through after a 45min drive Greensboro. The fan seemed to come on right as I was pulling out to the road right after I got my food. It's like, the longer it runs on the road, the hotter it gets when idling. If it's not being driven on the road, the temps stay decent. See top picture.

    How will it survive in the summer? It was in the 30s at the time.

    In the second pic, this is what the temp gauge does as soon as you turn off the car (I think this happens sometimes and not all the time, but I don't pay close attention to it to be certain). See bottom picture.


    In previous years, the temp would stay at the bottom near the "A" and "L". Now it is anywhere from the top of the "A" all the way up to the bottom of the "N".

    Pictures:
    http://imgur.com/a/rHfnp
  9. 91TwighlightGT

    91TwighlightGT Active Member

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    You haven't determined if the gauge is accurate. Until you know what the actual temperature is, we cannot help you. The gauges can and do go bad, and they aren't all that accurate to begin with. Get actual temperatures, then report back.

    As an aside, if the radiator has been flushed and you are sure it is not clogged internally, you may want to try cleaning it externally. A lot of debris can get in them over the years and affect cooling performance.

    Also, is your fan shroud cracked or broken in any location?
  10. Tavis

    Tavis New Member

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    My suspicion is starting to be the gauge too. It has done some awkward stuff recently. Such as: the other morning the temp was low, started driving for a few minutes, it jumped up to above mid-range, only a few minutes after normal driving, then within a few seconds, it drops back down to the "A" and "L" area.

    What device do I need to get to get the actual temps? I'm guessing there's a temp gauge sold that I connect somewhere under the hood.

    I'll look at the fan shroud the next time I am under the hood.
    The front side of the radiator looks mostly clean.
  11. 91TwighlightGT

    91TwighlightGT Active Member

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    Something along these lines...

    http://www.autotoolexpress.com/autintemgun.html

    They sell cheap ones, but I don't know how well they work. I would bet the shop that you have been taking it to has one, so you might see if you can't convince them to break it out for you when the thing is acting up. Based on what you have said, my bet is on a faulty gauge, temperature sending unit (I know you already replaced, but they can be bad right out of the box) or wiring.
  12. Tavis

    Tavis New Member

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    Thank you so much for getting back to me on this and your continued help. It is very much appreciated!
    If the temp gauge does turn out to be faulty, what are my options? I'd like to know (while driving) if the car ever is (truly) running hot.

    My speedometer has been acting up too, kind of "sticking" or "lurching forward", so I may as well replace/look into that too, if I'm in there replacing the temp gauge.
  13. jcgafford

    jcgafford Well-Known Member

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    have you pulled codes on this car? wondering if you have a code 61. (Code 61 - Engine Coolant Temperature Sensor ) a failed or failing sensor may be the problem, guage may be reading the bad signal from the sensor.
  14. 91TwighlightGT

    91TwighlightGT Active Member

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    Speedo is most likely a cable issue. Try to lubricate first (do a search on the correct stuff to lubricate with) and if that doesn't work then replace it.

    Replacing the gauge is easy, except that I don't know if the part can be bought anywhere. You might have to bite the bullet and get a used cluster. 85 MPH speedo clusters should be a dime a dozen, since nobody wants them :)

    Remember, though, that the temp gauge may be okay even if the readings are off. You can still have a faulty temp sensor or wire issue. LRS sells the wire, btw.

    http://www.latemodelrestoration.com/item/HDW-10884/Mustang-Sending-Unit-Wire-Terminal

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