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Replaced Radiator, but... HELP! Lol..

Discussion in 'General Chevy & GM Tech Questions' started by Al Stefanelli, Mar 3, 2010.

  1. Al Stefanelli

    Al Stefanelli Member

    Hey, people. I've not been here in a while due to work, but I have been busy working on "Loretta", my 1985 Chevy C20 3/4 Ton.

    Here's what I have had to do:


    • Rebuild top half of motor, which I found out was a 350 with 305 heads... Who knew?
    • Rebuild the transmission, which I think the guy screwed up, more on that in another post.
    • Rebuilt the carburetor.
    • Replace the brake booster and master cylinder
    • Replace the power steering pump
    • Replace the timing chain (used a dual sprocket one, whatever that means)
    • Replace the vacuum advance solenoid
    • Replace the wires, cap, rotor and plugs
    • Replace the thermostat
    • Replace the radiator, which brings me to my issue...


    The truck has run hot since I got it. After doing everything prior to the radiator, I decided that it needed replacing, since it was pretty much rusting from the inside out, requiring an almost weekly flushing. I have a flush kit installed.

    Well, I bought an OEM radiator from Auto Zone for $149.99 and the install was pretty straight forward and pretty easy.

    I ran the truck for about 20 minutes then took it out for a test spin. The temperature gauge did not move from 100 degrees, or extreme left.

    After perusing the Internet, I deduced that something is wrong with the thingie that sends the temperature information to my little gauge. After perusing more, I discovered that it was called a temperature control sensor, or at least that is what Auto Zone calls it.

    However, the picture from the AZ website does not match anything that I can see on my fairly filthy and dirty engine. Also, I found a connector wedged between the manifold and the block that was melting, and another wire on the carb that is barely hanging on to the terminal.

    So, I took a few pictures, which I attached and I am hoping that the combined expertise on this forum can help me.

    Oh, and I have a nasty exhaust leak that sounds like there is a gremlin under my hood banging on my manifold with a nine-pound ball peen hammer and I have no idea what the hell to than otherwise replace the manifold... Gah! I paid $1000 for this barn find and have already sunk well over $1000 in it and it still runs like ****. First gear winds up pretty high then slams into second gear, and that is with the new K&N crap that I had put on...

    But I digress... Here are the snaps:

    [​IMG]

    [​IMG]

    [​IMG]
  2. Stealth

    Stealth Epic Member 5+ Years 1000 Posts

    That doesn't look good, I don't have any specific help to give you but have you thought about replacing the engine with something newer or at least in better shape?
  3. tommyboy

    tommyboy Member

    I dont know about #1 and #3 but the 2nd photo looks like your electronic choke if that is the carb. in the background.

    Try picking up a Chilton Manual.
  4. Al Stefanelli

    Al Stefanelli Member

    Don't have the scratch for that.
  5. Al Stefanelli

    Al Stefanelli Member

    New Development...

    OK, so I get in the truck yesterday morning and the battery is completely dead. Took 1/2 hour to charge it off of my SUV, and then it only held about 9 volts. Ran it for about an hour, went into town, etc. Still low voltage. Got up this morning, battery dead again.

    Something is drawing current and the only thing I can figure is it had something to do with the temp gauge no longer working.

    There are a bunch of wires in there that are not connected to anything, but that is because all the sensors associated with the catalytic converters (or lack thereof) and other sensors have long ago since been removed.

    I am at a total loss here...
  6. RWK

    RWK Rockstar

    In your first photo:

    Looks like the sensor on the right with the 1 prong, is the temp. sending unit.

    The one of the left looks like a Thermal Vacuum Switch. But looks like something is missing off of it.
  7. Chris Miller

    Chris Miller Rockstar 100 Posts

    The first picture is the coolant temperature sensor, and the plug is broken off of it. Definitely replace it. It doesn't actually work your gauge, though. Look on the driver's side head between the first and second spark plugs. That's your temperature switch that works the gauge.
    The second picture is your electric choke. Don't worry about that.
    Third picture, hard to tell. If you find the temp switch on the head is unplugged, then that's probably what it is.
  8. bigdaddy77084

    bigdaddy77084 Rockstar 4 Years 500 Posts

    Put a temp gauge in it from the parts store. Heck get the one that has the oil,temp,alt all in one.

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