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Thread: Help Please -> Temp Gauge Problem?

  1. #1
    Join Date
    Apr 2001
    Location
    Phoenix
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    14

    Unhappy Help Please -> Temp Gauge Problem?

    Here is the deal. Car is a 93 325is w/60k miles. I replaced the water pump a few months ago. Everything fine. 4 days ago, on my way to work in Phoenix, the temp guage climbed from the usual 1/2 way up to about 3/4. It never overheated or got into the red. It fluctuated a bit up near 3/4, but pretty much remained constant.
    I just finished (a few hours ago) replacing the fan-clutch (a bud of mine told me it was shot) and the thermostat (didn't do it when I replaced the water pump, and I thought it was the overheating culprit). Went for a drive and bammo, still running hot. The car will warm up normally to 1/2 way (about 3-4 minutes) and then hang there for a few minutes. Then, the gauges quivers a bit, and begins its climb to 3/4. The upper radiator hose is hot to the touch and the radiator "looks" fine. I am out of ideas. Maybe the temp gauge sender on the side of the block? Please help. Thanks!

  2. #2
    Join Date
    Apr 2001
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    San Diego, CA
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    Did you replace the thermostat when you did the water pump? Getting the thermostat hotter than normal when they are old will often times kill them and they will stick half way closed.

    Also, does that car have a auxilliary fan? If so measure the continuity of the resistor that is inline with the power lead to it.

  3. #3
    Join Date
    Apr 2001
    Location
    Phoenix
    Posts
    14

    Yes, did the thermostat

    I just did the thermostat today. I also replaced the Aux fan thermo switch because I thought it was bad. The aux fan would come on when I turned on the AC, but it did not come on when the car was running hot (or at least, the temp gauge says it was hot).
    So, now, with the new thermostat and Aux fan swith, the car still is hot. I think it may be the actual sensor on the side of the motor.

  4. #4
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    If it comes on with the A/C but not when it's hot, then it probably is the sensor. But just to make sure the sending unit for the temp gauge isn't lieing and the temp is actually *normal* I'd stick a thermometer in it. Be careful it doesn't do a geiser on you.

  5. #5
    Join Date
    Apr 2001
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    Oh yeah.....

    When you turn the A/C on (and the aux fan comes on) does the temp drop back to normal? That will tell you a thing or two.

  6. #6
    Join Date
    Apr 2001
    Location
    Phoenix
    Posts
    14

    Sometimes

    I was playing around with just that. When I turn on the A/C, the temp gauge does move down toward normal. At least for a bit. The gauge is erratic. I took it for a drive and it stabilized at 3/4 or so. I revved the engine a few times (probably not smart, but the engine was not overheating) . The gauge went up a few degrees, then dropped quickly back to normal, then slowly climbed to a little less than 3/4. There is no way an engine can dissapate heat that fast.

    If the temp does go down with the ac on, what would that mean?

    Thanks for your replies!

  7. #7
    Join Date
    Apr 2001
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    It would mean that your problems are caused by the aux fan not coming on. Since the A/C forces it on then you should suspect the temperature sensors.

    But on a cool day, driving above about 45 mph is the same as having the fan come on. The temp should go down at cruising speed.

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