Replacing the faulty thermostat in a 2017 GMC Acadia is a critical DIY repair to prevent engine overheating. The process requires draining the coolant, swapping the thermostat housing, and meticulously refilling the system to restore proper engine temperature regulation and avoid costly damage.

Learn How To Change A Thermostat In A 2017 GMC Acadia

Hey there, fellow DIYer! So, your 2017 GMC Acadia is running a bit cool, or maybe it’s taking forever to warm up on those chilly mornings. You might see the temperature gauge dancing around more than it should. Before you panic about a huge repair bill, let me share a secret. The culprit is often a simple, inexpensive part called the thermostat.

I remember the first time my Acadia had this issue. I was driving the kids to school, and the heat just wouldn’t kick in. The gauge was stuck in the blue. A quick call to the shop had me bracing for a big bill. Then, a mechanically-inclined friend asked, “Have you checked the thermostat?” A few hours and a surprisingly small amount of money later, I had fixed it myself. The feeling of accomplishment was fantastic, and I saved a ton of cash.

Changing a thermostat in your 2017 GMC Acadia is a very achievable project for a weekend warrior. It requires more patience and care than complex mechanical skill. This guide will walk you through every single step, from diagnosing the problem to tightening the last bolt. We’ll talk tools, tips, and tricks to make the job smooth. So, grab your coffee, put on some old clothes, and let’s learn how to change a thermostat in a 2017 GMC Acadia together.

Key Takeaways

• Disconnect the battery: Prevent electrical shorts and ensure personal safety first.
• Drain coolant completely: Avoid messy spills and system contamination during removal.
• Use the correct thermostat: Ensure a proper fit with an OEM or equivalent part.
• Apply new gasket sealant: Create a tight seal to prevent future coolant leaks.
• Refill and bleed system: Eliminate air pockets for optimal cooling performance.
• Test for leaks and operation: Confirm the thermostat opens at the correct temperature.

Recognizing the Signs of a Failing Thermostat

Before you grab any tools, it’s smart to confirm that the thermostat is actually the problem. A faulty thermostat typically fails in one of two ways: stuck open or stuck closed. The symptoms are pretty clear once you know what to look for.

Symptoms of a Thermostat Stuck Open

This is the more common failure mode and often the easier one to deal with. When the thermostat is stuck open, coolant circulates through the engine all the time, even when the engine is cold.

• Poor Heater Performance: The most noticeable sign, especially in winter. The engine never reaches its optimal operating temperature, so the air blowing from your vents is lukewarm at best.
• Low Temperature Gauge Reading: Your dashboard temperature needle will stay low, often not moving out of the bottom blue or “C” zone even after 15-20 minutes of driving.
• Reduced Fuel Economy: Your engine’s computer runs a “rich” fuel mixture to warm up a cold engine. If it never warms up, it stays in this inefficient mode, burning more gas.

Symptoms of a Thermostat Stuck Closed

This is a more serious issue that needs immediate attention. A closed thermostat blocks coolant flow, causing the engine to overheat quickly.

• Rapid Overheating: The temperature gauge will climb into the red zone very quickly after starting the engine, often within 5-10 minutes of driving.
• Steam or Coolant Smell: You might see steam rising from under the hood or smell the sweet scent of coolant as the overheated system builds extreme pressure.
• Warning Lights: The “Check Engine” light and the high-temperature warning light on your dash will almost certainly illuminate.

If your 2017 GMC Acadia is showing signs of a stuck-closed thermostat, do not drive it. Severe overheating can cause catastrophic engine damage. Have it towed or fix it on the spot if you’re able.

Gathering Your Tools and Parts

Success in any DIY job starts with having the right gear. There’s nothing worse than being halfway through a project and realizing you’re missing a crucial socket. Here’s your checklist for learning how to change a thermostat in a 2017 GMC Acadia.

Essential Tools for the Job

• Basic Socket Set & Ratchet: You’ll need metric sockets, primarily a 10mm and likely an 8mm or 13mm for various clamps and brackets.
• Screwdrivers: Both flathead and Phillips head for hose clamps and electrical connectors.
• Pliers and Hose Clamp Pliers: Needle-nose pliers are helpful. Spring-type hose clamp plliers make removing those tricky clamps a breeze.
• Drain Pan: A large, clean pan to catch the coolant. A disposable aluminum roasting pan works perfectly.
• Funnel: For refilling the coolant system.
• Shop Towels or Rags: Coolant is messy and sweet, which attracts animals. Clean up spills immediately.
• Safety Glasses and Gloves: Protect your eyes from splashes and your skin from hot components and coolant.
• New Thermostat Gasket or O-Ring: This almost always comes with a new thermostat. Never reuse the old seal.

Choosing the Right Parts

For your 2017 GMC Acadia, you’ll need a thermostat designed for your specific engine. The most common engines are the 3.6L V6 and the 2.5L I4. Double-check your owner’s manual or the old part. You also need the correct coolant.

Coolant is Critical: The 2017 Acadia uses Dex-Cool coolant, which is orange/pink in color. It’s crucial to use the right type. Mixing different coolants (like green and orange) can cause a chemical reaction that turns into a gel, clogging your entire cooling system. When in doubt, buy the pre-mixed 50/50 Dex-Cool from your local auto parts store.

A Step-by-Step Guide to Replacing the Thermostat

Alright, the moment of truth. This is the core of learning how to change a thermostat in a 2017 GMC Acadia. Set aside 2-3 hours, work patiently, and follow these steps. Remember, the engine must be completely cool before you start. A hot cooling system is under high pressure and can cause serious burns.

Step 1: Draining the Coolant

You can’t open the cooling system when it’s full. Locate the radiator drain plug at the bottom of the radiator or, more easily, place your drain pan under the lower radiator hose where it connects to the engine or radiator. Loosen the hose clamp and carefully pull the hose off. Catch the coolant. It’s also a good idea to open the coolant pressure cap on the overflow reservoir to help it drain smoothly.

Step 2: Accessing the Thermostat Housing

On the 3.6L V6 engine, the thermostat housing is typically located on the front of the engine, connected to the upper radiator hose. You may need to remove an engine cover (just pulls off) and possibly move an air intake duct out of the way. Trace the upper radiator hose from the radiator back to the engine—it will lead you right to the thermostat housing.

Step 3: Removing the Old Thermostat

Once you have clear access, use your socket set to loosen the bolts holding the thermostat housing in place. There are usually two or three. Loosen them evenly and slowly. As the last bolt comes out, the housing will loosen. Be ready for a little more coolant to spill out. Lift the housing off. The old thermostat will be sitting in its seat, often held in by friction or a small clip. Note which way it’s facing—the spring side goes into the engine. Take a rag and thoroughly clean the mating surface on the engine where the gasket sits. Any old gunk left behind will cause a leak.

Step 4: Installing the New Thermostat

This is the easy part. Take your new thermostat and place it in the engine housing seat in the exact same orientation as the old one. Place the new gasket or O-ring onto the housing. Some gaskets use a bit of sealant—follow the instructions that come with your part. Carefully set the housing back in place and hand-tighten the bolts. Then, using your ratchet, tighten the bolts in a criss-cross pattern to ensure even pressure. Do not overtighten! These are often small bolts going into aluminum, and they can snap easily. Snug is perfect.

Step 5: Refilling and Bleeding the System

Reconnect the lower radiator hose and any other hoses you disconnected. Close the drain plug if you opened it. Now, with your funnel in the coolant overflow reservoir, slowly pour in the new Dex-Cool coolant. Pour until the coolant level reaches the “Cold Full” mark on the reservoir. Start the engine with the radiator cap still off (or the reservoir cap off). Let the engine run, and you will see the coolant level drop as the thermostat opens and the system fills. Keep adding coolant slowly to maintain the level. Once the level stabilizes and the upper radiator hose feels hot (meaning the thermostat has opened), you can put the cap back on. Top off the reservoir to the “Cold Full” line.

Thermostat Options and Coolant Specifications

When buying a new thermostat, you might see a couple of options. Here’s a quick breakdown to help you choose the right part for your 2017 GMC Acadia.

Feature	Standard Thermostat	Fail-Safe or High-Performance Thermostat
Opening Temperature	Typically 195°F (90°C) – The factory specification.	May be the same temp, but with a different design.
Key Difference	A standard mechanical wax pellet design.	Designed to fail in the open position to prevent overheating if the mechanism breaks.
Best For	Direct OEM replacement for standard driving.	Added peace of mind for those concerned about overheating risks.
Coolant Type	Dex-Cool (Orange/Pink), Pre-mixed 50/50 or Concentrate. The 2017 GMC Acadia cooling system capacity is approximately 10-11 quarts, but you will only need to replace what you drained (usually 1.5-2 gallons).

Post-Installation Check and Troubleshooting

You’ve buttoned everything up. The real test begins now. A proper check ensures you did the job right and helps you spot any potential issues early.

The Essential Test Drive and Inspection

Start the engine and let it idle. Watch the temperature gauge closely. It should slowly rise to the midpoint (around 210°F) and stay there steadily. Feel the upper radiator hose. It should stay cool for several minutes, then suddenly become hot as the new thermostat opens. This confirms it’s working! Take a short drive, then park on a clean piece of cardboard or your driveway. Check for any drips or leaks around the thermostat housing. Also, verify your heater is now blowing hot air.

Common Issues and Simple Fixes

Even with care, small hiccups can happen. Don’t worry, they’re usually easy to fix.

• Air in the System (Overheating): If the gauge spikes, you likely have an air pocket. Let the system cool completely, open the reservoir, and start the engine again. Let it run with the cap off, adding coolant as needed to burp out the air.
• Leaking Housing: A small drip from the housing means the seal isn’t perfect. You may need to slightly tighten the bolts in a criss-cross pattern (again, don’t overtighten). If it persists, you may need to re-clean the surface and install a new gasket.
• Check Engine Light: It’s possible for the light to come on if the engine ran too cool before. Use an OBD2 scanner to clear the code after the repair. If it comes back, there may be another issue, like a faulty coolant temperature sensor.

Maintaining Your Acadia’s Cooling System

Replacing the thermostat is a great time to think about overall cooling system health. A little preventative care keeps your Acadia running smoothly for years and avoids future breakdowns.

Simple Habits for Longevity

Coolant doesn’t last forever. GM recommends changing Dex-Cool coolant every 5 years or 150,000 miles, whichever comes first. Mark your calendar! Also, make it a habit to visually check your coolant level in the overflow reservoir every month or two when the engine is cold. It should always be between the “Min” and “Max” lines. A slowly dropping level can indicate a small leak you can fix before it becomes a big problem.

When to Call a Professional

While learning how to change a thermostat in a 2017 GMC Acadia is very doable, know your limits. If you discover significant corrosion, broken bolts, or persistent leaks you can’t fix, there’s no shame in calling a mechanic. It’s cheaper to have them fix one issue than for you to accidentally create another.

Conclusion: Enjoy the Warmth and the Win

And there you have it! You’ve just successfully diagnosed a common issue, gathered your tools, and replaced a critical component on your 2017 GMC Acadia. More than just fixing a car, you’ve gained confidence, saved a significant amount of money, and gained a deeper understanding of how your vehicle works.

The next time you get into your Acadia on a cold morning and feel that warm air blasting from the vents within minutes, you can smile knowing you made that happen. The steady temperature gauge on your dashboard is a testament to your effort. Remember, the key to any DIY job is patience, the right information, and taking pride in the work. Enjoy the drive, and the satisfaction of a job well done.

Frequently Asked Questions

What are the symptoms of a bad thermostat in my 2017 GMC Acadia?

The most common signs include the engine running colder than normal and the heater blowing lukewarm air, or conversely, the engine overheating. You might also notice erratic temperature gauge readings or a check engine light related to coolant temperature.

Where is the thermostat located on a 2017 GMC Acadia?

The thermostat is housed inside a plastic housing connected to the engine’s upper radiator hose. On the 3.6L V6 engine, you’ll typically find it on the front of the engine, making it relatively accessible compared to some vehicles.

What tools do I need to change a thermostat in a 2017 GMC Acadia?

You’ll need basic sockets and wrenches, a drain pan for coolant, and a new thermostat gasket or housing assembly. It’s also smart to have new coolant and a funnel ready for the refill process after you complete the thermostat change in your 2017 GMC Acadia.

How long does it take to change a thermostat in a 2017 GMC Acadia?

For a DIYer, expect the job to take 1 to 2 hours. This includes time to safely drain and capture coolant, replace the thermostat, and refill the cooling system, which is the most time-consuming part.

Is changing the thermostat on a GMC Acadia difficult for a beginner?

It’s considered a moderate DIY job. The steps are straightforward, but it requires careful handling of hot coolant and precise refilling and bleeding of the cooling system to prevent air pockets, which can lead to overheating.

Do I need to drain all the coolant to change the thermostat?

Yes, you must drain a significant amount of coolant from the radiator to a level below the thermostat housing. It’s not always necessary to drain the entire block, but you will lose several quarts and should be prepared with fresh, Dex-Cool compatible coolant for refill.