Jeep Wrangler Thermostat Problems

Why is my Jeep Wrangler overheating? Every Jeep comes with a thermostat and a valve that controls the engine temperature. When a Jeep’s engine is cold, the thermostat stays closed. This blocks the flow of coolant to the radiator allowing the engine to warm up faster. Once the engine hits a certain temperature, the thermostat opens up. This allows the flow of coolant into the radiator to keep the engine from overheating.

When your thermostat is working as it should, the temperature gauge will be steady. However, when it moves up and down, then it’s a sign there is a problem. Failure to fix the problem quickly could result in more expensive damage.

In this post, we cover Jeep Wrangler thermostat problems.

Why Is My Jeep Wrangler Thermostat Failing?

Weakened Springs

A Jeep Wrangler’s thermostat is usually located where the top radiator hose meets the engine. As aforementioned, it opens and closes in response to coolant temperature. One reason why your Jeep Wrangler’s thermostat fails is that it has become too weak – weakened springs.

When this happens, it can become stuck closed. A closed thermostat is an immediate problem that you need to resolve. The radiator relies on coolant to keep the engine at an optimal temperature. Without the coolant circulating, the engine temperature will quickly build up. This may cause major damage to the engine and other components.

Build up of Grease and Dirt

A thermostat can also stay stuck open due to a buildup of grease, dirt, debris, or corrosion. As such, it prevents the thermostat from closing properly. The normal operating temperature of a Jeep Wrangler’s engine is between 194 F (90 C) and 221 F (105 C). If the thermostat stays open, the engine temperature will drop below normal when driving.

This is true especially if driving on the highway in cold weather. When this happens, there is a lack of heat in the engine, and you may see the check engine light come on. Lack of heat to the engine will result in increased fuel consumption. Additionally, you’ll find higher amounts of carbon buildup in various components of your Jeep Wrangler’s engine.

Leaks Near Thermostat Housing

Another reason why your thermostat may be failing is there are leaks near the thermostat housing. A leaking thermostat housing leads to a low coolant level. In turn, this results in an inoperative heater. This is because the distribution of coolant throughout the engine is severely compromised.

With no or reduced coolant flowing to the radiator, your Jeep Wrangler’s engine is vulnerable to excessive heating. Usually, you’ll notice high readings on your temperature gauge when this happens.

What are the Symptoms of a Bad Thermostat

Sympoms of a bad thermostat include:

• Overheating
• No heat
• Blown head gasket

Overheating

The most common sign of a bad thermostat is overheating. When your engine starts to overheat, the temperature gauge will spike. If it goes past the red line, you should take immediate steps to resolve the issue. The first step is to stop your car and switch off your engine. The next step is to allow your radiator to cool before you check your thermostat.

If you allow your Jeep Wrangler’s engine to overheat, the metal will get hot, and a piston will weld itself into the cylinder. Once this happens, your engine is damaged.

Also read: jeep wrangler 4 vs 6 cylinder

No Heat

If you detect no heat in your Jeep Wrangler, the thermostat may be stuck open. An open thermostat means the coolant will constantly circulate through the engine. No heat means higher fuel consumption which means you’ll spend more money.

Blown Head Gasket

If your Jeep Wrangler runs too long without coolant circulating through the vehicle’s engine, the head gasket will blow. Signs of a bad head gasket include a lot of white smoke from the exhaust, rough idle, and bad fuel mileage.

Can I Drive With a Bad Thermostat?

If your thermostat has issues, the first thing you may notice is a spiked temperature gauge or warning light. If you notice this, get off the road immediately and shut down your Jeep Wrangler. You should shut off an overheating engine immediately, then call your local mechanic or towing service to tow your vehicle to a repair shop.

If the thermostat is stuck closed, coolant will not flow through your engine and may cause engine failure. If the thermostat is stuck open, engine failure may not occur, but you may notice poor performance, bad fuel economy, and an ineffective heater. If you notice these signs, have your thermostat checked and replaced at your earliest convenience.

How do I Identify a Bad Thermostat?

If you suspect your Jeep Wrangler has a faulty thermostat, there are a few checks you can run. Before carrying out the checks, make sure the engine is always cold. Now, remove the radiator cap and start the engine.

Check if the coolant is flowing or swirling. If it’s flowing or swirling, the thermostat’s stuck open. However, if it’s not flowing after 10 minutes or more, the thermostat’s stuck closed.

Turn off the engine and replace the radiator cap. Check the temperature of the radiator hoses. Is one cooler and the other hot? If this is true, then the thermostat’s stuck closed.

Lastly, carry out the temperature test. This involves the removal of the thermostat and heating up a pot of water to the stamped temperature on the thermostat.

Then grab the thermostat using a pair of pliers and hold it under the hot water. If it opens at the specified temperature, then it’s working. Otherwise, it’s faulty.

Final Words

A Jeep Wrangler’s thermostat can fail due to weakened springs, build-up of dirt and grease, or failure of the thermostat’s housing. While the thermostat does not wear at the same rate as a tire does, it eventually fails. When this happens, take steps to have it replaced. We recommend preventative maintenance. Basically, anytime your Jeep Wrangler’s cooling system gets services, have the mechanic check the thermostat.