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Temp sending unit??? Still jacked up

Discussion in 'The Garage' started by stallion85, Jan 20, 2004.

  1. stallion85

    stallion85 1/2 ton status

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    I just basically rebuilt half of my 350 this past weekend. Everything went well...except of course the few snags you always run into. /forums/images/graemlins/smirk.gif I had the heads rebuilt which came with a new temp sending unit. It had an adapter on it because the threads weren't the right size. I went to the NAPA parts store and bought a brand new one that was the proper size. Anyways when my truck is idling not even that hot the temp gage goes up to 210 and runs in the red when I am driving. I replaced the thermostat and am sure that the gage in the dash is still incorrect. My question is how do the temp sending units work are they calibrated or something???? That is the only thing that should have changed but I was just wondering what would cause it? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
     
  2. bablazer73

    bablazer73 1/2 ton status

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    Re: Temp sending unit???

    There are 3 different sending units for the temp guage. Make sure you have the right one. I don't know what the difference is. Maybe just an air pocket somewhere? Is the radiator getting hot? does heat come out the heater? if it doesn't, something isn't flowing.
     
  3. 99firehawk

    99firehawk 1/2 ton status

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    Re: Temp sending unit???

    IS it on hot all the time even when cold? Does it jump from cold to hot instantly?
     
  4. rick88blaze

    rick88blaze 1/2 ton status

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    Re: Temp sending unit???

    Jeff,

    If you decide to put another one in there, We can knock that out the same time we put in our heater cores. /forums/images/graemlins/thumb.gif /forums/images/graemlins/grin.gif

    Rick

    Jeff,

    Please send me your email address, that way I have it when I go to Korea. /forums/images/graemlins/thumb.gif
     
  5. stallion85

    stallion85 1/2 ton status

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    Re: Temp sending unit???

    [ QUOTE ]
    There are 3 different sending units for the temp guage. Make sure you have the right one. I don't know what the difference is. Maybe just an air pocket somewhere? Is the radiator getting hot? does heat come out the heater? if it doesn't, something isn't flowing.

    [/ QUOTE ]
    Well the heater core has been out for the last six months so I am not sure if the heat is blowing /forums/images/graemlins/grin.gif The gage is definately not reading correctly... it starts at normal then goes up within minutes. I drove 300 miles from Utah to Vegas with it like that so I know the truck isn't really over heating. I did not know there were three different types of sending units. May be I just got the wrong one. /forums/images/graemlins/tongue.gif
     
  6. R72K5

    R72K5 Banned

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    Re: Temp sending unit???

    make sure you have unit for the year make model of the truck,
     
  7. lukebaby1

    lukebaby1 1/2 ton status

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    Re: Temp sending unit???

    I found that usually the thread size is different for the one thats correct to what the size of the hole in the head jacket is. I just went and got some brass reducer bushings and put them together to step up or down to the size needed. It may stick out a little farther once you get them all together but just make sure the wire doesn't run to close to the exhaust manifold or header.
     
  8. the_goat

    the_goat 1/2 ton status

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    Re: Temp sending unit???

    It doesn't sound like this is it and you probably checked already but just in case. Mine kept showing that my truck was overheating because the wire kept hitting the exhaust. I zip tied it back and haven't had a problem since.
    John
     
  9. stallion85

    stallion85 1/2 ton status

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    Re: Temp sending unit???

    [ QUOTE ]
    It doesn't sound like this is it and you probably checked already but just in case. Mine kept showing that my truck was overheating because the wire kept hitting the exhaust. I zip tied it back and haven't had a problem since.
    John

    [/ QUOTE ]

    That could be the problem, the wire has heat wrap around it and it is hanging down more than normal. I will try moving it first and see if that helps, if not I guess I will try buying a new sending unit. Thank you for the replies /forums/images/graemlins/thumb.gif
     
  10. fatboy

    fatboy 1/2 ton status

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    Re: Temp sending unit???

    As above you have wrong sender I had that problem once also, and if you really want to, warm it up, open cap on radiator and then put one of those little temp prob dillies (the ones you can buy for like 10 bucks) in the coolent. I know that it is not block temp but common it cant be 100 degrees different /forums/images/graemlins/burb.gif
     
  11. stallion85

    stallion85 1/2 ton status

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    Re: Temp sending unit???

    /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif Ok I changed the heater core this weekend and put yet another temp sending unit on the head. Still same problem truck warms up and the gage slowly goes all the way to the max????? It can't be grounding out somewhere right because it would immediately jump to 260?? I followed the wire to the back of the engine and it seems to be fine. It is wrapped in a heat shield coil thingy. Any other ideas from someone??? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
     
  12. 99firehawk

    99firehawk 1/2 ton status

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    Re: Temp sending unit???

    Coolant temp in the head will be 20-40 degrees hotter then in the intake, due to the heat from the combustion chambers. try moving your sender to the intake and see hot hot it runs.
     
  13. stallion85

    stallion85 1/2 ton status

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    Re: Temp sending unit???

    Where would I put it in the intake? Has anyone else done this? I have an edelbrock intake manifold if that makes a difference. The only thing is it never did this till I put new heads on. Maybe the gage is bad now? Or maybe I could just re wire it? /forums/images/graemlins/doah.gif /forums/images/graemlins/doah.gif /forums/images/graemlins/doah.gif
     
  14. the excuse

    the excuse 1/2 ton status

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    Re: Temp sending unit???

    i got mine from autometer and an autometer gauge it moves from the resting pin to the first line on the gauge. it reaches 100 on a 30 minute drive. its a 250 degrees gauge.
     

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