What's that sender/switch for again????

Discussion in 'The Bench' started by Electra-fied, May 16, 2018.

  1. Electra-fied

    Electra-fied GR8WHTE

    I'm sure its posted somewhere in the forum, I just cant find it through the search engine. On 455 by oil filter/pump there is the oil sender for the dummy light on dash. but what is the sender on the back of the head for? I see two/three wires on it and I can't see them on the FSM wiring diagram for my model year.

    I am installing aftermarket gauges and I'm going to be using the senders for water and oil on the front of engine and top of intake. I'm just curious what the sender at back of head(left head as I'm standing in front of the car) is for.
  2. 1973gs

    1973gs Well-Known Member

    It's a temperature switch that turns your blower motor on low speed when the engine reaches operating temperature. You'll notice that there is no off position on your blower switch, just low, medium, and high. You can't use it for a temperature gauge, it's just installed in a bolt hole, not a water jacket.
  3. Electra-fied

    Electra-fied GR8WHTE

    Got it, now I see it on the diagram! Thanks for the info. I plan on using "T' fittings so I can still have the dummy lights along with the gauges. Car ran great yesterday until I got home. I shut if off and it dropped about 50% of the coolant out of the overflow about 2 minutes later. No light came on and there was no indication that there was an issue when driving in traffic. I would like to see what temp is before I go replacing t-stat, water pump, and/or radiator.
  4. knucklebusted

    knucklebusted Well-Known Member

    Use an infrared thermometer. Makes it easy to check the temp of the thermostat housing and the in and out radiator hoses to see if she's cooling good.

    Was the overflow tank full when you started out cold? Is the cap holding pressure? Those are the two things I'd check as they are easy and quick. Once it cooled off, how much was in the radiator and was any in the overflow resevoir?
    john.schaefer77 likes this.
  5. Electra-fied

    Electra-fied GR8WHTE

    It back filled into the reservoir and then all poured out the overflow hose. I usually keep the overflow about 25% full, the car had been leaking fluid over the winter from the tstat housing. I had to tighten the upper rad hose a few times to get it to stop. The radiator was always full to about an inch below the cap. I figure last nights "dumping" was around a 1/2 to 1 gallon before it stopped. It was 74 yesterday, its 82 today...I head out of work into rush hhour traffic in about 20 minutes, we'll see if its a repeat today.
    Last edited: May 16, 2018
  6. Electra-fied

    Electra-fied GR8WHTE

    ok...i got gauges installed. So, is there extra ports that I can utilize for both the oil sender and the water temp sender without having to "t" off the current locations in manifold and next to oil pump assy?
  7. knucklebusted

    knucklebusted Well-Known Member

    For oil, you pretty much have to "T" to get the oil pressure and the factory light/gauge to work. For temp, you can block off the heater hose and use the intake nipple hole for the other temp gauge if there aren't any other areas in the area of the thermostat.
  8. yachtsmanbill

    yachtsmanbill Well-Known Member

    I removed the TCS and plugged it. I'd use that... ws


  9. Electra-fied

    Electra-fied GR8WHTE

    You know, I did that too! I'll remove that and put the sender there. Thanks for the idea! I knew I was missing something!

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