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Temp Gauge on a 94 GMC

Discussion in 'GM Powertrain' started by 94 Jimmy P/U, Jul 29, 2010.

  1. 94 Jimmy P/U

    94 Jimmy P/U Member

    Hi yall the Temp Gauge on my 94 GMC 2500 W/ 350 Engine is acting up.

    It will either sit @ 100 degrees (even @ operating temp) or somtimes flutter back & forth & Check gauges light comes on when it does this & runs a little rough esp around 40 to 50 mph .

    I'm now fully disabled on my left side due Cerberal Palsy got worse & not able to drive trucks & run heavy equipment like i used to.

    so i had friend change the temp sending unit thinking this might be the problem. but the truck still has the problem .

    Now for my question My friend put Teflon tape on the sending unit . Will this affect the sending unit or do i have another problem like a gauge going out or thermostat sticking?

    if the gauge is going out will i have to replace the whole gauge cluster or can i put a manual temp gauge under the dash?

    thanks for the help yall

    Last edited: Jul 29, 2010
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    You have the ability to put in a manual temp guage. Or you can change the cluster.. that really is up to you. And the sputtering etc, isnt related to the Temp guage. The temp switch (sending unit) only sends a signal to the guages. The Temp Sensor could be going bad as well (that is the sensor that tells the computer what the motor temp is for the fuel trims etc). But you will want to do some further troublshooting to figure that out..
    When was the last time it had a Tune up?? the cap and rotor on these trucks are notorious for going out after a year, sometimes a bit more but usually just a year. That will cause a sputter similar to what you are refering to.
  3. 94 Jimmy P/U

    94 Jimmy P/U Member

    Murdog: I Just changed the plugs , wires & wanted to change the cap & rotor also. But listened to my one of my buddy's & he talked me out of it & i knew better .

    have another buddy of mine who is ASE Certified who i go back to HIGH SCHOOL with he now lives about 2 hours from me now talked to him also last night he told me the same thing about the Temp Sensor but did'nt mention the cap & rotor (maybe it did'nt cross his mind lol)

    The last time the rotor & cap was changed was after i bought the truck from my boss/ buddy in May of 08' so it may be time to change it. I Know this much it running just a little rough has made a difference in Fuel mileage. & is driving me nuts. lol


  4. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    I would for sure do the cap and rotor ASAP.. And the temp sensor i would look at as well it is about $10-$13 part... It is brass and doesnt need any tephlon tape since it has a pipe thread so it seats quite nicely.
  5. 94 Jimmy P/U

    94 Jimmy P/U Member

    Thanks Murdog : WILL Do on all the above esp the cap & rotor . I've said it before on here before this is my 1st GM p/u TRUCK in 12 to 13 yrs & having to learn about them all over again . lol

    btw is the temp sensor located in the intake as well ? i'd have my buddy who is ASE Certifed & like a brother to me do it but like i said he now lives about 2 hours east of me & dont want to chance it going that far right now .


  6. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    The Temp sensor is on the intake.. The temp switch (as mentioned for you guage) is mounted on the block between the #1 and #3 cylinders.
  7. 94 Jimmy P/U

    94 Jimmy P/U Member

    Thanks for the help i just ordered the parts. & it may be a day or two before i can get back toward the computer but will keep ya informed .


  8. 94 Jimmy P/U

    94 Jimmy P/U Member

    sorry it's been so long but it was the temp sensor on the intake manifold.

    Had to take the new sensor back out & take the teflon tape off the sensor that a friend of mine put on there after our friend who was the mechanic told us not to do but my other friend was a hard head & i'm the one who had to take it back out & correct that problem .

    We was told that teflon tape would interfere w/ the reading on the temp gauge & it would make the motor miss & it did but as my thermostat is a 210 & it read @ 160 :( I DO AS My friend (the mechanic tells me but other friends want to do things there way ugghh)

    oh btw i did replace the rotor & cap for good measure after i replaced the temp sensor

    later yall

    Last edited: Aug 16, 2010
  9. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Everything working right now?? or are you still having the same problem?
  10. 94 Jimmy P/U

    94 Jimmy P/U Member

    Thanks for the Help Mike!

    Everything's cool for now The "Jmmy" (as the old timer truck drivers that i grew up around would call ANY GMC ;) ) Is running like he should . Now it's time to put some Tires on the front. Good thing i work for a buddy on the side in the BIG Truck tire business who still can get me some new 235 85 16 tires from the wharehouse @ cost for a 3/4 ton . ;)


    Last edited: Aug 17, 2010

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