It's possible to test the thermostat in your 2.0L, 2.4L Chrysler vehicle to see if it's stuck open or stuck closed without having to take it out from the engine and I'll show you how to do it.
As you're probably already aware, when the thermostat stays stuck closed, your vehicle will overheat. When it stays stuck open, the engine will never warm up and your heater will not work. Well, whether the thermostat is stuck closed or open, I'll take you through the whole process in a step by step fashion.
In this article, I'll also show you how to check that the electric fan (or fans) are coming on at the appropriate coolant temperature.
To help you navigate this article, here are its main points:
- Important Suggestions and Tips
- Symptoms of a BAD Thermostat
- TEST 1: Thermostat Operation
- TEST 2: Fan Operation
- Thermostat Basics
- Other Tips and Suggestions
- More Test Articles
Important Suggestions and Tips
TIP 1: To take advantage of the test info in this article, you'll need a scan tool that has Live Data capability... since you'll need to check the coolant temperature with it. A simple code reader can't do this.
You don't need the factory scan tool or an expensive professional technician level scan tool. A generic scan tool will do great and I've written this article with this tool in mind: Actron CP9580 Scan Tool Review.
TIP 2: To test the thermostat, the engine has to be started and it has to warm up as close as possible to its normal operating temperature. This means the coolant will get very hot (but not overheat) and so you should not open the radiator cap under any circumstances or you run the risk of getting burned by the hot coolant.
Opening and/or removing the radiator cap with a warmed up or hot engine can cause you severe burns. Your safety is your responsibility... be careful, use common sense and think safety all of the time.
TIP 3: It is super important that you start out with a cold engine to successfully test the thermostat.
If you have been running the engine for an extended amount of time... let it cool down completely. This is important for safety reasons and for the accuracy of the thermostat test.
Symptoms of a BAD Thermostat
The thermostat in your 2.0L or 2.4L equipped Chrysler car or minivan will fail in one of two ways: It will either stay stuck at its open position and let coolant circulate all of the time or it will stay stuck closed. When it stays stuck closed... your car or mini-van will overheat.
Here are some more specifics:
CASE 1: If the thermostat is stuck open, you'll see the following symptoms:
- BAD gas mileage.
- If it's winter time, the heater will not work.
- If your vehicle is equipped with a temperature gauge (and not just a temperature light), it will always show you a low reading or none at all.
- Won't pass the State Emission's Test.
Most folks are usually surprised to find out that a stuck open or missing thermostat wreaks such havoc with gas mileage but it's true.
CASE 2: If the thermostat is stuck closed, you'll see the following symptoms:
- The engine will overheat.
- cooling fans come on, but the engine does not cool down.
- If your vehicle is equipped with a temperature gauge, it will max out.
- If your vehicle is equipped with a temperature light, it will shine nice and bright to let you know that an engine meltdown is occurring.
OK, let's get testing...