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Replacing Temperature Sender

Discussion in 'The Garage' started by Robert D, Nov 23, 2005.

  1. Robert D

    Robert D 1/2 ton status

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    Hey guys, I'll be getting off of work today ~4:30 and would like to replace the temperature sender so the gauge will be working when I drive to San Antonio from Austin (~70m) this evening. I'd like to be somewhat aware of what I need to do before I do it so I can knock it out as quickly as possible this evening (given I have about 1.5-2 hrs of daylight when I get off of work).

    From what I've read, on my '91 350 TBI the temperature sending unit will be bolted into the head near the #3 cylinder on the drivers' side head. I will stop by and pickup a new ratchet and deep socket to fit the replacement and hope it fits the one on the truck (my tools are in California, getting a new set sent to me for Christmas). As for fluid, with this being on the head, will I lose any fluids? I'd like to be prepared with enough to replace what I lose.

    Thanks for the help everyone. (I don't have my repair manual at work with me)
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Undo the petcock on the lower drivers side of radiator , your gonna have to let a lot of green stuff out , until the block and heads drain . I try to collect most of it in a 5 gallon bucket , but there isn't a great way to keep a funnel or anything on a stock truck , and get it all .

    If you want to do it right away after work ,and you drove it , wait a few until the radiaotr cools enough to remove the cap . And do the drain .

    Then just unbolt it like you plan on .
     
  3. Robert D

    Robert D 1/2 ton status

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    Sounds like a plan, when I replaced the temperature sensor on Saturday I hadn't driven the truck all day and didn't even think of letting out the coolant before removing the sensor. SPRAY! :haha: I think it wasn't so much from being hot but from the coolant being full at the time. I'm not too worried about losing the coolant I drain out, as I have 2 full bottles of antifreeze to put in. What I am somewhat curious about is getting air in the cooling system. Is this not a problem with the 350? On the Porsche I had to bleed the system.
     
  4. Leper

    Leper 1/2 ton status

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    I am guessing the sensor for the gauge and the sensor for the ecu are different. I just replaced the one for the ecu. I put tape on the new one and pulled the old one off and stuck the new one in. Lost about 4oz of coolant.

    You must be quick.
     
  5. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Don't worry about air in the system . Just fill it , run it , wait for the thermostat to open , and add some more .

    The overflow bottle , and the radiator cap take care of the rest :D
     
  6. 4xcrazy

    4xcrazy 3/4 ton status

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    if you're fast enough with the swap, you don't have to drain the system at all, you will still lose some coolant, and it's a bit messy, but remove the old one, and have the new handy, and yank n push/twist really quick...i did this once, like i said, alittle messy, but did save most of the coolant. :p:

    yes, the temp gauge sender and the ECM sender are two different units.
     
  7. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Tape on it ? It needs a good ground , and won't leak without tape . At least mine don't :D
     
  8. Leper

    Leper 1/2 ton status

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    Old habit...Tape at the top of threads. Probably doesn't need it, just habit for me.
     
  9. Robert D

    Robert D 1/2 ton status

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    Good, sounds like I should be able to knock this out within the time-frame I have of daylight (otherwise I buy a lightsource from a parts store or sears). Something I noticed when replacing the other temp sensor is I could not get it to bolt all of the way in...though I plan to go back over it once I have a deep enough socket (I had to resort to a set of pliers and my gorilla hockey-grip). Don't get me wrong it isn't barely in there, it just has 2-3 threads still showing and I didn't want to torque it in too much. Thanks for the help. I plan to pickup a cheap ratchet and socket on my way home so this one will come out easier :p:
     

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