Replacing the Thermostat for the 5.3

Discussion in 'How-to Guides' started by Mean_Green_95, Jul 21, 2009.

  1. Mean_Green_95

    Mean_Green_95 Epic Member 5+ Years 1000 Posts

    I can't believe nobody has posted a how to on this simply procedure. If somebody already did, then I'm sorry. Well, I already did the swap b/c my truck over heated and I decided to put up a how to with a few pics.

    Tools Needed:

    Slip Jaw Pliars
    Flat Head Screw Driver
    10mm 1/4" socket
    1/4" extension, about 1' extension
    1/4" rachet
    RTV silicon gasket maker or equivilant
    water hose and nozzle
    antifreeze catch


    1st. Park the truck near a water faucet and let the engine cool down.
    2nd. Remove the air inlet tube that runs between the air box and the throttle body.
    3rd. You don't have to remove the belt, but doing so would make access to the thermostat completely unrestricted.
    4th. Follow the LOWER radiator hose to the thermostat. It is on the passenger side of the radiator.
    5th. Remove the incredibly difficult hose clamp off of the lower radiator hose on the thermostat side.
    6th. Use some sort of catch, such as a oil drain pan, an put it under the truck.
    7th. Pull the lower radiator hose off of the thermostat. Let all the anti-freeze drain out.
    8th. Using a 10mm socket, remove the 2 bolts hooding the thermostat in place.
    9th. Remove the thermostat. On this motor, the thermostat is built into the thermostat housing.
    10th. Pull the new thermostat out of the pretty box. Apply a little bit of RTV silicon gasket maker or something such as to the thermostat housing where the o-ring seats. This will hold the o-ring in place while putting the thermostat in place. Put the o-ring in place and make sure it is being held in place..
    11th. Place the new thermostat in place, and bolt it back in.
    12th. Inspect and replace, if necessary, the hose and hose clamp.
    13th. Put he hose on the new thermostat. Put the clamp back into place.
    14th. Replace belt if removed.
    15th. Replace air intake tubing.
    16th. Fill up reservoir with a 50/50 mix of water and new antifreeze. This is where the water hose, nozzle, and faucet come in handy.
    17th. Start up truck and inspect for any leaks.
    18th. Sit in truck and monitor engine temp. Put the ac on if not too cold to see how hot the truck gets. It shouldn't get above 210.
    19th. Top off reservoir, after the truck, cooled as need.

    This whole process should takk no more than an hour, unless you run into problems like I did. My problems resulted in my suggestion of RTV gasket maker and insspection of hose and clamp. My o-ring didn't seat, cusing a leak, and my hose clamp broke on the bottom side, resulting in another leake.

    Hear is a pic of the loaction of the thermostat. I took this pic after I removed the air inlet tubing. That is the new thermostat.


    Here is the old thermostat. I was able to play with it like a kid plays on a trampoline.

    And this is the brrken hose clamp.

    I hope this will help somebody in the future...
    Last edited: Jul 21, 2009
  2. Mean_Green_95

    Mean_Green_95 Epic Member 5+ Years 1000 Posts

    BTW, you can always bring your old fluids to an oil change place and most of the time they will gladly dispose of them for you.
  3. Turbopuppy

    Turbopuppy New Member

    Running a colder 'stat allows you to run hotter plugs, right? Anybody have a part number for plugs that run a step hotter?

    Oh yeah, the computer controls the fan speed. Though the colder stat opening temp starts flow to radiator, the fan still won't start until 190-195 degrees. How's that fixed? Tuner?
  4. Mean_Green_95

    Mean_Green_95 Epic Member 5+ Years 1000 Posts

    In my opinion, stick with the stock plugs. These motors are really particular when it comes to there plugs. A lot of guys on the site swear my the AC Delco plugs, gapped at .40, not .60.

    But if you want to run hotter plugs, I would start a new thread about it in the performance section. You'll get more answers that would be better then mine.

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