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Temperature gauge capped out?

Discussion in 'The Garage' started by ascuro, Oct 20, 2005.

  1. ascuro

    ascuro Registered Member

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    Well, after several hours of weeding through wires, I replaced my temp sender and my temp gauge finally works (sort of). For the first time, the needle actually moves on its own, but it caps out at H when the engine warms up. It's a 70 blazer, and I've got a new crate 350 in it, with long-tube headers - could the headers be warming up the sender that much more? Or does it sound like maybe my gauge resistor is bad? (it's the only thing I haven't replaced really).
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    If the guage is pegged to the hot side then the sender wire is grounded somewhere. GM uses grounds to activate all the electrical components.
     
  3. diesel4me

    diesel4me 1 ton status Premium Member

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    Wrong sending unit..?

    You might have a sending unit made for an idiot ight,not a gauge..they ground out to light the bulb,that might peg the neddle..if not,and its the right sender for a gauge,it could be the wire grounding as suggested,or maybe the gauge itself is off..--or maybe it IS overheating?? :confused:

    I'm not sure if there is a resistor separate from the gauge,or if its part of it..but I've seen more than one gauge that was not accurate,,and fooled someone into thinking it was overheating,when a meat thermometer in the radiator said otherwise..migt be time for aftermarket gauges.. :crazy:
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Does it start out at "c" then slowly go to "h" as it warms up?

    If it was an idiot light switch it would go from C to H instantly, as that's an on/off switch.

    The resistors on the back of the gauges DO go bad, I've seen and heard of others that have experienced it, but it's pretty rare. GM MIGHT have "tuned" the gauges with the resistors, I've noticed that they have different colors printed on them. Tuning it isn't a fix for your problem, but be careful if you decide to try some. It would be interesting to test resistance on a couple of them.
     
  5. ascuro

    ascuro Registered Member

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    It crept up slowly from C to H, then just hung out around H at running temp. It didn't cap out all the way to the right, so I knew it wasn't a ground problem. Changed out the resistor tonight, and it's sitting at a comfortable 1/3rd of the way up. Gonna have to test out the actual coolant temp with a thermometer soon though, just for some peace of mind, hehe. Thanks for all the help guys!

    Tomorrow = moving on to fixin' the gas gauge, hehe.
     

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