2004 Isuzu Ascender V8 5.3L Thermostat with Housing Assembly ACDelco 15-11057

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In this video, we're going to be working with our 2002 Chevy Suburban. We're going to show you how to remove and replace the thermostat on your 5.3L V8.

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Here are the items you'll need for this repair: drain pan, jack, jack stands, coolant, flat blade screwdriver, 15mm wrench, 15mm socket, ratchet, socket extension, torque wrench

Remove the coolant cap before draining your coolant or lowering the level, as with the cap off air can flow through and let the coolant drain faster.

Raise and support your vehicle. We're using a lift to make it easier to show you guys what's going on at home, but this job can easily be done in the driveway or your garage with a jack and jack stands. Place a drain bucket under the front driver side of your radiator. There's actually a little drain hose tucked up here nice and neat. We're going to flip that down and hold it over our drain bucket while we loosen the petcock, and allow the radiator to drain.

Loosen the hose clamp just after the mass air flow sensor. This is going to be the second one back from your air box. We'll do this using a flat blade screwdriver. Wiggle and twist the boot to release it from the mass air flow sensor. You may need to use your screwdriver to help peel it back here. These tend to get stuck on pretty good. We'll also remove the one at the throttle body. We'll need to disconnect the hoses from their clamps here. You can either try prying it out there, or there's also a little clamp at the bottom here that you should be able to compress, pop loose with a flat blade, and remove the intake runner from the vehicle.

Now, it's not 100% necessary to remove the upper fan shroud when doing this. You can get in there and do it without. However, it's going to make it a lot easier on us, and it only takes a moment. Plus, it will make it easier to show you guys what's going on. Should you remove it, we'll pop this hose clamp out with a flat-blade screwdriver. Remove the hose. Remove the two 10mm screws at the top of the fan shroud with a 10mm socket and ratchet. We're going to use our trim tool from 1A Auto to pop these up. You can also do it with a flat-blade screwdriver or a pair of side cutters. You don't have to remove the center pin fully. Just pop it up, and wiggle the rest of the pin out. There's one at the back on each side, like you saw there. Then, another one here up by the radiator. That one also has a twin on the opposite side. Pull back and lift out the upper radiator shroud.

Before removing your serpentine belt, make sure your vehicle has a belt path diagram under the hood somewhere. If this is missing or faded, you can just draw another one onto the plastic with something like a paint marker. Using a 15mm wrench on the tensioner, rotate the nut clockwise to slack the belt. Pop the belt off of whatever pulley is easiest for you to reach. Let the tension off the pulley and remove your serpentine belt.

Using a pair of pliers, and we do have a drain bucket set up underneath our vehicle here, release the clamp on the lower radiator hose at the thermostat housing and move it back. I like to wiggle the hoses, twist them, to try and get them to release. We'll just tuck that hose up and out of the way. Remove the two 10mm bolts on the thermostat housing. Do this with the 10mm socket and ratchet. We're just going to allow that to hang and drain out in a more controlled fashion. Remove the thermostat and housing from the vehicle.

Here we have our old thermostat that we removed from our vehicle and our new part from 1AAuto.com. As you can see, these parts are exactly the same. We have the same two bolt mounting location. It comes with a nice new O-ring. The thermostat is actually a part of the housing assembly here. The tops look exactly the same and have the same fitting for the bottom radiator hose. Now, the thermostat can fail and be an item that you replace on its own. Also, any time you lower the cooling level in the vehicle, because you're making a repair, we recommend that you replace these. Their inexpensive, easy to change, and it's cheap insurance. If you've overheated your vehicle to replace this while replacing the root cause of the problem, because a wax pellet in here is actually what allows it to expand and compress during temperature changes. If that pellet melts, your thermostat doesn't function and your vehicle's going to overheat again. If you're in there, it's likely this has failed. Their inexpensive, easy to change, and it will make sure that you can do the repair right the first time. This new part from 1A Auto will go in direct fit, just like our original equipment and fix you up right.

Install your new thermostat and housing assembly along with the two 10mm bolts. Torque these bolts to 11 foot-pounds. Reinstall the lower radiator hose and slide the clamp back into place.

Install the belt over the front grooves of the harmonic balancer or crank pulley. Bringing the right side over top of the pulley. We'll then go over top of the water pump and loop under the power steering pump, over the alternator, under the idler pulley. I'll keep this piece in my hand. Make sure that everything is seated because this one's kind of tight and you're going to want the room. Using my 15mm wrench, we'll take the tension off of the tensioner pulley, slide the belt over, double-check that our path is right, all of the belt is properly seated, and then let the tension back on.

Lift up on the upper radiator hose and reinstall the upper fan shroud. There are two little pins, one on each side, that'll help you align everything. Then, we'll reinstall our four plastic clips by popping the base in, and then locking the center pin down. Reinstall the two 10mm screws at the top. Tighten them down with a 10mm socket and ratchet. Reinstall the hoses back into their clips.

Reinstall the intake tubing. It's easiest to set it onto the throttle body. Reengage the hoses into their clips. Then, get the boot over the air box. Then, tighten down both clamps with a flat-blade screwdriver.

Refill your coolant. This vehicle uses the orange coolant Dex-Cool. Make sure that it is either pre-diluted or if you buy concentrated full strength that you mix it 50/50 with distilled water. We'll fill it up as much as it'll take, and then back our vehicle outside to finish bleeding the system while it's running. Don't be afraid to overfill it, because once our vehicle runs and gets up to temperature the thermostat will open and that fluid will all go into the engine block.

Set your vehicle with the fan on the lowest speed, set to hot in the vents so you can feel the warm air coming out of the vehicle. This will also open any bypass valves that prevent coolant from entering the heater core when shut off. This is another place that air pockets can build up. Now we'll let our vehicle run up to temp, and keep the coolant topped off in the process.

Now we just had to add just about a gallon of coolant to the vehicle once it got up to temp. Now we'll keep an eye on it, wait for it to finish bubbling, our heat to get hot, and the level to stabilize before we'll finally top off our fluid and take our vehicle for a test drive. Once your fluid is finished bleeding, and it's topped off reinstall your cap and test drive your vehicle.

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