How to Tell if a Fan Clutch Is Bad

December 8, 2020Car Care and Revamp
Jane Davis

Apart from being a freelance writer and moving expert, Jane is also an art and museum lover.

Another day, another car problem to fix. But the truth is, as long as you use something, it’s going to break at some point. Everything comes with an expiration date, which is why today we will help you find out how to tell if a fan clutch is bad. And don’t worry. In case you were not even aware your vehicle has one or what’s its purpose, we’ll explain where it is located and what is doing over there, so you know all about it before you call your car shipping company.

Cars are complicated things, and although they keep adding more buttons and screens to them, somehow, no button can resolve a problem. Or diagnose it. Sometimes you need to go from one mechanic to another until someone finally figures out what’s the actual problem. So, if your dad or uncle didn’t explain to you how to check a fan clutch, we’re here to help.

What Does a Fan Clutch Do?

Before we get to the fun part, let’s see what this thing actually works and what its purpose is. This is not something you’ll find among driving tips for beginners or learn about in car racing games. So if you skipped an episode or two of your favorite car TV show, we are here to help you get all the information you need.

This is a thermostatic engine cooling fan that can work at lower temperatures when cooling is not necessary, which allows the engine to warm up quicker and relieves the unnecessary load from it. Once the temperature goes up, the clutch engages, and the engine power drives the fan. It is moving the air and cooling down the engine. It is usually located in front of the water pump and consists of the following components:

  • Fluid chamber,
  • Bi-metal thermostat,
  • Sealed bearing,
  • Fluid reservoir,
  • Mounting flange.

What Temperature Does a Fan Clutch Engage?

The majority of them engages when the air temperature goes around 170°F, which means that engine temperature is around 180-190°F. Usually, they can reduce it by about 20°F before disengaging.

Faulty fans can lead to many problems
Check out our guide to find out everything you should know about these fans

Are There Different Types of Fan Clutches?

Depending on the type of vehicle, there are three main types that you can encounter. So pay attention to that if you’re looking to buy some of the best import cars or buying a car from a dealer.

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2 Basic Types of Fan Clutches: Thermal and Non-Thermal + the Electronic One

Before we get to the main part, here is everything you should know about different types of fans:

  • Non-thermal – this model operates solely on the shaft speed of the water pump. At a higher speed, the silicone fluid can’t transfer the energy, and it almost free-wheels and removes its load off the engine. It provides a steady flow of cooling air, but it is always engaged, which means that it does not save fuel as much as thermal models. But on the other side, this is a more affordable option, so that is something to keep in mind.
  • Thermal – this model works in correspondence to the underhood temperature. When the hot air blows across the radiator, it starts heating a mounted thermal spring. When the spring is heated enough, it starts turning, and by doing so, it opens valve ports. A silicone fluid from the reservoir then goes through those ports and comes into a clutch’s working area, engaging it and driving the fan. The speed of spinning depends on the exact type of thermal clutches. For example, a standard-duty one starts turning at 60-70% of the water pump shaft speed when engaged.
  • Electronic – this model operates pretty much the same as thermal ones, but there’s an ECM/PCM signal that controls the level of engagement of EV clutches. In this process, the following manufacturer-specific input variables are used: Coolant Temperature, Intake Manifold Temperature, Engine Oil Temperature, Transmission Oil Temperature, and A/C Pressure. So it is not modulated directly by the temperature, but it relies on various sensors that point out when to engage or not.
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How to Tell If a Fan Clutch Is Bad? Signs That Show Its Failing

Before embarking on a road trip along the most famous routes in the United States, you might want to know how to tell if your fan clutch is bad. Now, this is not something that should make you experience driving stress or road rage. It is not like you put the wrong gas in your car. But still, it is good to know these things whether you’re alone on the road or driving in New York City or driving in Los Angeles. You can spare yourself from trouble if you know how to check a fan clutch and notice on time when something is wrong. So, here are the most common signals or red flags you should not ignore.

Engine Overheating

This is one of the most common symptoms that points out that you should check what’s going on. When cooling fans performance drops or fails when the clutch can’t engage properly, which leads to overheating first, but it can trigger much more serious issues if it is not treated on time. Many drivers can tell that they have a problem with overheating, but they can’t detect what’s the cause, so they try adding water to the radiator, but it is safer to call someone who is an expert and knows how to recognize the real problem.

Lack of Performance

Another common signal that something is wrong is the lack of power, a drop in acceleration, and reduction of fuel efficiency. When there is a problem with the clutch, it results in a permanently engaged fan, which causes excessive drag on the engine.

Excessive Loud Noise

When there is a problem, and the fans are stuck in the operating position, that means they are working even when they shouldn’t. In those situations, the engine can produce a loud noise that can be audible all the time, whether the engine is hot or cold. It can also damage the radiator if the blades disintegrate or flex excessively.

Air Conditioning Problems

Air-condition systems can also suffer in situations like these. Defective fans can cause numerous problems from burning smell and lukewarm air to overheating when idle.

Use our tips to help you find out if everything is running smoothly
Use one of these methods to test the performance of this component

How Do You Diagnose a Bad Fan Clutch? Test Your Car in 3 Steps

Diagnosing car problems can be tricky if you are not familiar with how things work. Maybe you don’t know how to tell if a thermostat is bad or how to add brake fluid, but you have to start somewhere. That is why today, we bring you the best method that will help you do a proper inspection and notice any flaws on time.

How to Test Fan Clutch – the Best Method(s)

Whether you’re thinking about shipping a car cross country or you’re buying a used car, it is good to know a few tricks and be able to perform some simple check-ups by yourself. So here is how to check fan clutch:

  • While the engine is off, thoroughly inspect the blades, make sure they are in good condition and well secured,
  • Pay attention to the surrounding area to see if there are any signs of oil leakage because thermostatic and fluid-coupling clutches are filled with silicone-based oil. So if you see any signs of leakage, it is time for replacement,
  • Try to move the entire assembly back and forth with your hands. If you notice excessive play, it could be due to the water pump, but if it is not the pump, then you should replace the clutch,
  • Try to spin it with your hands. It should show some resistance because silicone-based oil is thick and viscous. But if the blades start spinning easily or they are too hard to spin, you will need to replace it,
  • Another thing you can do is to turn on the engine and let it idle. If your model is thermostatic, search for that thermostatic spring in front, the fan shouldn’t start turning before the engine reaches operating temperature. So if it starts rotating when you turn on the engine, but also if it’s not rotating 5 minutes after the operating temperature has been reached, it is time for a replacement.

Take a Look at This Video for More Testing Ideas

If just the thought that something might be wrong with your car is giving you driving anxiety and you’re not feeling comfortable, take a look at this video to see how you can perform this simple standard test that will answer all of your questions.

YouTube video

How Long Do Fan Clutches Last?

Everything has its expiration date, and sooner or later, things break or wear out, which is why you should pay attention to every aspect of your vehicle, and not only it’s exterior. However in this case, there is no such thing as a set mileage at when this part might stop working correctly. And there’s not much you can do except to pay attention to some signs and symptoms we mentioned that signalize that something is not working properly. Also, you will rarely be in a situation to repair clutches. In most cases, they need to be replaced, and that is an excellent occasion to also inspect the radiator and cooling fan, which your mechanic will probably do.

When’s the Right Time to Replace It?

Many mechanics say that you should replace it together with the water pump when it fails. They both age at the same pace, so if one fails, the chances are high that the other one won’t survive much longer. Keep in mind that if you can switch to thermal if you have a non-thermal, but not vice versa. Anyways, if you’re planning to relocate, inspecting these parts should be an essential part of preparing a car for shipping.

Your car should be looking good, inside and outside
Don't focus only on the exterior of your car. Its components require special attention and regular check-ups

Inspect Your Clutch Before Booking Door to Door Auto Transport

Whether you opt for enclosed auto transport or an open trailer, it is always good to ensure everything is in good condition and working, so you don’t have to deal with mechanics and experience any unpleasant surprises. Also, whether you’re up to off-road driving or city driving, it is your duty to check everything. Knowing that everything is in order will help you enjoy the journey and be at peace. So try to learn as many tips and tricks as possible, and you’ll be OK.

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