Question about 1991 GMC Sonoma

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Block heater removal 99 GMC 3500

I am replacing a block heater, but found thagt the screw has been stripped. I am wondering what the purpose of the screw is, and if I can drill it out. Is it a set screw, or does it have a blind nut? Any info would be great!!

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Has like a retainer on back that stretches across the hole to pull it in tight. Small bar like thing approx. 1/4" wide x 1" - 1-1/2" long. That screw is threaded into that retainer.When you buy new one you'll see what I mean. You may want to try a pair of pliers or vise grips on fitting for cord and try spinning it counterclockwise to see if things will loosen up at all. My main concern would be where that retainer will drop to, if it comes off.

Posted on Jan 31, 2009


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We were told by Canadian Tire that the block heater is leaking.. we are confused if we should change the block heater or block core? when we had the water pump replaced we had heat for 20 minutes once all...

You block heater is a heater that should be screwed into the engine block.
Yes, it can leak.
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Diagram on how to replace heater core in 99 expedition

Removal & Installation 1997-2002 To Remove:
NOTE: Heater core must be vacuum leak tested before it is remove from vehicle if a heater core leak is suspected.
  1. Drain engine coolant.
  2. Remove instrument panel.
  3. For 5.4L (4V), if quipped, remove junction splash shield.
  4. For 5.4L (4V), if quipped, disconnect starter relay cable. ford-03-00-3579.gif

  5. For 5.4L (4V), if quipped, remove junction block bracket.
  6. Clamp inlet and outlet heater hoses.
  7. Disconnect heater hose from heater core by gently pressing it toward heater core.
  8. Remove A/C plenum demister adapter.
  9. Disconnect vacuum line.
  10. Remove 13 plenum chamber top screws.
  11. Remove blend door assembly from case.
  12. Remove heater core.
To Install:
NOTE: If needed, clean and lubricate coolant hoses with plain water.

  1. Install heater core.
  2. Install blend door assembly to case.
  3. Install 13 plenum chamber top screws.
  4. Connect vacuum line.
  5. Install A/C plenum demister adapter.
  6. Connect heater hose to heater core.
  7. Release all clamps from inlet and outlet heater hoses.
  8. For 5.4L (4V), if quipped, install junction block bracket.
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  10. For 5.4L (4V), if quipped, install junction splash shield.
  11. Install instrument panel.
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