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How to Replace Thermostat 05-11 Honda Civic

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How to Replace Thermostat 05-11 Honda Civic

Created on: 2017-12-12

This video shows how to drain the coolant, remove the thermostat, and refill the coolant properly

  1. step 1 :Draining the Coolant
    • Open the hood
    • Raise and support the vehicle
    • Loosen the drain plug with needle nose pliers
    • Let the fluid drain into a drain pan
    • Tighten the drain plug by hand
  2. step 2 :Removing the Thermostat
    • Have a drain pan ready
    • Loosen the hose clamp on the upper radiator hose
    • Disconnect the hose
    • Loosen the 10mm bolts on the thermostat housing
    • Separate the bracket from the housing
    • Remove the thermostat housing
    • Remove the thermostat with a pick
  3. step 3 :Installing the Thermostat
    • Insert the thermostat into place
    • Place the thermostat housing on
    • Place the bracket to the thermostat housing
    • Tighten the 10mm bolts to the thermostat housing
    • Connect the hose
    • Tighten the hose clamp to the upper radiator hose
  4. step 4 :Refilling the Coolant
    • Remove the radiator cap
    • Top off the radiator with the appropriate mixture
    • Leave the funnel in the radiator
    • Place a drain pan beneath the radiator
    • Run the vehicle
    • Watch the air bubbles
    • Refill coolant as needed while the vehicle is running
    • Let the coolant reach operating temperature
    • Wait for the coolant level to stop dropping or the bubbles to seize
    • Check for heat to come out of the vents
    • Turn the vehicle off
    • Reinstall the radiator cap
    • Top off the overflow bottle if necessary
    • Test drive the vehicle and monitor the coolant levels

Tools needed for replacement

  • General Tools


    Jack Stands

    Drain Pan

    Floor Jack

  • Materials, Fluids, and Supplies

    Rust Penetrant

    Paper Towels

  • Pliers, Cutters & misc Wrenches

    Needle nose pliers

  • Ratchets & Related

    Socket Extensions


  • Screwdrivers & Related

    Flat Blade Screwdriver

  • Sockets - Metric

    10mm Socket

Installation Video
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Hi, I’m Mike from 1A Auto. We’ve been selling auto parts for over 30 years!

To open up the hood, pull the release. There are two spots you can put the prop rod. There's one here. That's sort of the normal one. If you need to work on the engine, you don't want to be hitting your head. You can actually lift the hood up further and push the prop rod into this opening here. That puts the hood almost vertically and gives you a lot more space to work. You'll have to raise and support the vehicle so you can at least get to the drain at the front of the vehicle, so at minimum, you'll want to raise the front.

We're going to use our two-post lift. The radiator drain is located right here. There's a nice opening in this plastic shield. If this is too tight to take off with your fingers, you can use a pair of pliers to loosen it. Just make sure that when you loosen it, you've got your drain pan or bucket ready because it will come pouring out. I've just got it started with my pliers. I can finish taking it off with my hand.

If you go up top and you open the radiator cap, it will drain even faster. With this drained, I will reinstall the plug. Don't forget to do this before your refill with coolant so it's ready and in place. Just use your hand to tighten it because you don't want to overtighten it. That feels good there. Wipe up any coolant.

Now you're ready to refill the radiator and bleed the system. We're going to remove the thermostat, which is located here in the lower radiator hose. There's two bolts that hold it in and then two bolts on this bracket here that hold the O2 sensor wires. We're going to move the upper radiator hose out of the way so you can see what we're doing better, but you shouldn't have to actually remove it to do the thermostat. We're just doing it to give you a better view.

I'm using some slip-joint pliers to prop on the locks, move the clamp down, and loosen this hose up. I'm just going to put it down out of the way. These are all 10-millimeter bolts, so these two are just holding this bracket on. I'm going to remove those first using a 10-millimeter socket and ratchet the right way. Break the bolt free.

You can't move this bracket too far because it's on these wires, but you can move it over just enough. Break the 10-millimeter bolts free that are on both sides. I break them free and just kind of spin them out using the socket and little extension, and hold onto that bolt so it doesn't fall. Grab this and just kind of break it free. A little bit of coolant's going to dribble out even though we drained it.

There's our thermostat. To remove it, just kind of grab onto it. Kind of wiggle it, and break it free from the seal. If it's really stuck you can take a flat bladed screwdriver. Just put my hand in there to catch it. Make sure you have drain buckets underneath the car when you're moving this even though you drained the coolant, there's still some coolant in the engine that's going to come out. Come on. I'm going to take this little pick and just sort of break the seal free. Just gently right around the edge here. That'll break it free. They get kind of baked in there. It's stuck. There's the thermostat.

To reinstall the thermostat, dry this area where the seals going to go best you can. Install the thermostat. It's actually two little rubber bumps on the seal. They've got to match these two little openings inside the casting. That's going to sit just like that. Otherwise, you should be mindful that this little loophole goes towards the top, but those little rubber locators help get it in the right position. That's going to sit in there like that.

We'll take our lower gooseneck and put it back into place. Reinstall the bolts. I'm going to get them started by hand because these are steel bolts going into aluminum. Make sure they thread down nice and smoothly. Our ratchet extension and tighten these down evenly. Reinstall our bracket.

Two smaller 10-millimeter bolts in there. I'll just tighten these up. All they're doing is holding this bracket on. They don't have to be super-tight. They're going in aluminum. You don't want to crack it, so just snug them up and they'll be fine.

If you removed this upper hose, reinstall it. Line it up where it was. With a flat bladed screwdriver, I'm just going to pop it and it'll snap into place. We've got a special radiator funnel set up. This will help us fill and bleed the system. We're going to fill it with a 50/50 mix of the appropriate coolant. We've got this topped off.

Now I've just kind of gone in and just squeezed the upper and lower radiator hoses a little bit. It gets any real big air bubbles out of there. I'm going to start and run it with the thermostat open, and we should see any bubbles that are remaining in the system bubble out of the funnel. You can see as the engine's running any air bubbles in the cooling system are starting to escape.

When it comes up to temperature and the thermostat opens, you should see a lot more air bubbles come out. Our system is bled. The lower hose is warm, so the thermostat is open. I'm going to shut the car off. This coolant's really hot. We put our little plug in here and we take our funnel out.

I'll actually take the extra because our reservoir is a little empty. Put that in here. Don't want to overfill, just fill it to the high mark. Remove the rest of our funnel. The coolant's right at the top of the radiator, which is perfect. Reinstall our radiator cap. Wipe up any spilled coolant. The job is complete.

Thanks for watching. Visit us at for quality auto parts, fast and free shipping, and the best customer service in the industry.

Tools needed for replacement:

    General Tools

  • Funnel
  • Jack Stands
  • Drain Pan
  • Floor Jack

  • Materials, Fluids, and Supplies

  • Rust Penetrant
  • Paper Towels

  • Pliers, Cutters & misc Wrenches

  • Needle nose pliers

  • Ratchets & Related

  • Socket Extensions
  • Ratchet

  • Screwdrivers & Related

  • Flat Blade Screwdriver

  • Sockets - Metric

  • 10mm Socket

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