Temp gauge reads cold

Discussion in 'General Motoring' started by Ratbert, Jan 18, 2006.

  1. Ratbert

    Ratbert Guest

    On a ~100-mile drive, the temperature gauge on our 98 SL2 never went
    over about 1/8. The heater seemed to be blowing out plenty of warm air
    on us. Does this sound like a bad thermostat, CTS, or something else?
     
    Ratbert, Jan 18, 2006
    #1
  2. Ratbert

    p_vouers Guest

    chances are it is the CTS for sure. The CTS and the IAT are the same
    sensors and I would replace both of them with the new version (brass)
    that is available at napa.
    should fix the problem
     
    p_vouers, Jan 18, 2006
    #2
  3. Ratbert

    James1549 Guest

    Do you have a thermometer to put in one of your dash vents? Turn the
    blower on low or medium and at the "vent" setting. Do not run the AC.
    Once the engine is warmed up, the air in the vents should be blowing
    between 125° and 140°. If not, I would start with the thermostat.
    Anything less than 120° will not be sufficient in extreme cold
    weather.

    James
     
    James1549, Jan 19, 2006
    #3
  4. Ratbert

    Ratbert Guest

    Luckily, we don't have extreme cold weather. But thanks for the tip.
    I'll try that out.
     
    Ratbert, Jan 19, 2006
    #4
  5. Let the car idle for a while and see if the temperature gauge climbs up
    to the normal 'middle' point. If the indicated temperature climbs up at
    idle while standing still but stays low while car is moving forward
    through the air, it is probably the thermostat. If so, get a new
    thermostat in there soon as a cool engine means cool oil that will not
    lubricate very well and the engine wear will be about 10x normal.
     
    David T. Johnson, Jan 19, 2006
    #5
  6. Ratbert

    James1549 Guest

    << as a cool engine means cool oil that will not
    lubricate very well and the engine wear will be about 10x normal. >>

    I will never agree with that part of your statement! James
     
    James1549, Jan 19, 2006
    #6
  7. Ratbert

    Ratbert Guest

    In the continuing saga, I drove the car to and from work today with a
    meat thermometer in the vent. It read 150°F when I got to work (and
    again when I got home). I let it idle in the garage for five minutes or
    so, and the temp gauge went up to just under 1/4. If I read this
    correctly, neither your test, nor the one suggested by James indicate a
    bad thermostat.

    Should I take p_vouers advice and go buy a CTS? Is there some other
    test I should do to know for sure?
     
    Ratbert, Jan 20, 2006
    #7
  8. Ratbert

    James1549 Guest

    If your air temp was 150°, your thermostat is working properly.

    Time to buy a CTS. If problem persists, your temp gauge is not reading
    properly.

    James
     
    James1549, Jan 20, 2006
    #8
  9. Ratbert

    Ratbert Guest

    OK thanks. You said NAPA in your other post. Does NAPA have its own
    brass CTS, or was NAPA simply shorthand for "a auto parts store, not
    necessarily the dealership?"
     
    Ratbert, Jan 20, 2006
    #9
  10. Ratbert

    p_vouers Guest

    napa has the brass tip ones.. believe they are made by eichlen or
    something like that.
     
    p_vouers, Jan 20, 2006
    #10
  11. The viscosity of the oil blend is established and tested by the oil
    manufacturer based on its expected operating temperature. If the
    temperature is below that point, the viscosity will be higher and the
    oil will not lubricate as well, causing increased (and completely
    unnecessary) wear of the engine components. I've seen engines fail
    after being operated for 10-20k miles with a leaking thermostat that
    should have lasted another 100k miles. On Saturns, the timing chain
    will sometimes fail after extended operation at cool temperatures.
    Thermostats are cheap so put one in if you need one. I agree with
    others, though, that the original poster needs a CTS, not a thermostat.
     
    David T. Johnson, Jan 20, 2006
    #11
  12. Ratbert

    James1549 Guest

    Personally I would purchase from the dealer. But if NAPA or another
    store is closer, go for it. Replace the AIT sensor at the same time, I
    think they are the same sensor. James
     
    James1549, Jan 20, 2006
    #12
  13. I missed the early part of this thread that gave the year of the car...

    in OBD1 Saturns ('91-'95) there are 2 temp sensors in the head - a 2 wire,
    that is the same as the IAT sensor that goes teh the PCM, and a 1 wire that
    only runs the guage. OBD2 )'96-'02) have 1 sensor of the 2 wire variety
    that goes to the PCM, which then sends that same signal on up to the guage.
    Sooo - if you have a "91-'95, and it is running fine, no rush to replace
    that sensor.
     
    Kevin M. Keller, Jan 21, 2006
    #13
  14. Ratbert

    Ratbert Guest

    Thanks for clearing that up. I've been looking for that extra sensor
    that is supposed to be the same part as the CTS, with no luck (this is a
    1998 model).

    By the way, I put in a new brass coolant temp sensor from Kragen (Napa
    was closed and Saturn is 80 miles away) last night. Today, the temp
    went up to about 1/4 after the engine warmed up. That's more like what
    I'm used to. Hopefully that will clear up the cruddy mileage we've been
    getting lately, too.

    Thanks to everyone for the help. I love this newsgroup!
     
    Ratbert, Jan 21, 2006
    #14
  15. Ratbert

    blah blah Guest

    98's dont have 2 CTS's.
    A CTS that fools the computer into think it is still cold will run rich.
    A rich running engine will also run cooler.
     
    blah blah, Jan 21, 2006
    #15
  16. Ratbert

    p_vouers Guest

    that extra sensor is at the front grill area.. that box that holds your
    air filter look in fron and below it.. you'll see it attached to the
    intake plastic horn that goes to the filter box..
    I would replace it also.. for it will influence your milage.
    In cool weather my saturn (97) runs just a tad over 1/4 and in the
    summer just a tad over 1/2. When my sensor was bad my rpms were also up
    when cold around 1500 -1800 now when cold they are at about 1100 then
    when she warms up drops to 900
     
    p_vouers, Jan 21, 2006
    #16
  17. Ratbert

    Ratbert Guest

    OK, _now_ I found it. It's not obviously bad like the (cracked) CTS.
    But I'll see if I can get one of those, too.
     
    Ratbert, Jan 21, 2006
    #17
  18. NO. That is the Intake Air Temperature sensor. It is identical to the
    Coolant Temperature Sensor.

    In '91 to '95 S-series Saturns, there is a 2nd Coolant Temperature sensor
    that runs the guage on the dash. It is different that the other 2 sensors,
    in that it only has 1 wire coming off of it.
     
    Kevin M. Keller, Jan 21, 2006
    #18
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