Fan Clutch Not Disengaging? Keep Reading to Get This Issue Addressed Correctly!

While many contemporary automobiles employ electric cooling fans to keep the engine cool, many older vehicles still require a mechanical fan clutch. The fan clutch is a temperate device, which means that its functioning is temperature dependent, and it is often positioned on the water pump or another belt-driven fan pulley.

Fan clutch not disengaging or the fan clutch spins freely until a particular temperature is reached, at which point it fully engages, allowing the fan to operate at optimum efficiency. Because the fan clutch is a component of the cooling system, any problems with it frequently result in overheating and other problems.

Why Fan Clutch Not Disengaging

Sometimes it’s overlooked. Check that the hub’s bolts are not mechanically locked. If you have a horton, there are two bolt holes in the front where you may thread 2 3/8 bolts to manually lock the hub in the event of clutch failure. Also, with the engine off and the key off, the hub should be locked; yet, when the key is switched on, the hub is normally unlocked. 

The second reason why your fan clutch doesn’t disengage is when the engine is turned off and no air is supplied to the fan, the clutch disengages and I may spin it manually.

With the engine turned off, activate the clutch fan, engage the I/E spring, and apply air to separate the clutch and free wheel.

What you need to do is obtain an air compressor and shoot air straight into the fan hub to see if that releases it. If not, your air sel in the fan hub is faulty. Then you have two options: buy a super kit and rebuild it (which comes with instructions but requires a mechanically inclined individual) or just buy a remnant fan hub and replace it.

How Does Fan Clutch Work

A fan clutch is a temperature-controlled linkage between the water pump shaft and the fan that allows the fan to run at low speeds while being disengaged at higher speeds. By eliminating the burden that the fan exerts on the engine, it can run more efficiently.

So, how exactly does it work?

It is entirely dependent on the sort of fan clutch you select.

Non-Thermal Fan Clutches

Non-thermal clutches work only on the water pump’s shaft speed. The clutch allows the fan blade to spin at almost a 1:1 ratio at low and idle speeds. 

At high speeds, the silicone fluid within the clutch loses its capacity to transmit energy from the shaft to the fan clutch body (and hence the fan), allowing the fan to practically free-wheel and thereby eliminating its burden from the engine.

Non-thermal clutches produce a constant flow of cooling air but are constantly engaged, resulting in lesser fuel savings than thermal-style fan clutches. Non-thermal clutches, on the other hand, are a less expensive choice than thermal clutches.

Thermal Fan Clutches

The thermal fan clutch responds to temperature changes beneath the hood. As hot air passes over the radiator, it warms a thermal spring located in front of the clutch. As the spring heats up, it twists, allowing valve holes within the clutch to open. Silicone fluid stored in a reservoir is permitted to travel via these open ports and into the clutch’s operating region. This engages the clutch and causes the fan to spin. When the engine cools, the thermal spring returns and seals the valve ports, disengaging the fan.

Electronic Fan Clutch 

An electronic fan clutch performs comparable duties to thermal and torque-limiting versions, although it is not directly regulated by temperature or speed. Instead, the engine control module (ECM) or fan control module uses various sensors to determine when to engage the fan clutch, such as when the engine is idle, when the vehicle is moving slowly, when the air conditioning compressor is engaged, or when the engine temperature exceeds a certain threshold.

Fan Clutch Bad Symptoms

The fan clutch is the most crucial part of the cooling system. A properly operating fan clutch is crucial to the correct operation of your engine, as it helps to keep the temperature within a safe range.

There are a handful of signs that the fan clutch is failing. A defective fan clutch usually causes a few signs that warn the driver of a possible problem. Understanding the signs of a damaged or failed fan clutch is critical because it will help you avoid engine damage.

A faulty or failing fan clutch can potentially leave you stuck with costly repair fees, so pay attention to the indications listed below to see whether your fan clutch is damaged or failing:

Vehicle Overheating

An overheated engine is frequently the first indicator of a damaged or failed fan clutch. Most drivers notice when their engine overheats, but they don’t immediately suspect the fan clutch is to blame.

The fan clutch regulates the functioning of the cooling fan, and if it fails, the fan may not engage correctly or at all. As a result, it will stop the fans or prevent them from operating at optimal efficiency, resulting in engine overheating and other serious problems if left untreated.

INSUFFICIENT HEAT IN WINTER is another prevalent issue caused by opposing fan clutch failure. When the fan clutch is seized, it remains engaged all of the time, overheating the engine.

Loose and Wobbling Fan 

A failing fan clutch can cause the engine fan to become loose and unstable. The wobbling of the fan can occasionally be noticed when driving, especially at high speeds such as on the interstate.

To see whether the fan is loose, start the engine when the car is parked, open the hood, and look for wobbling as the fan rotates. Oil leaking from the clutch hub is another symptom that the engine fan is loose.

Excessively Loud Cooling Fans 

Excessively noisy cooling fans are another sign of a defective or failing fan clutch. If the fan clutch becomes locked in the engaged position (which is not unusual), the fans will completely engage even if it is not safe for them to do so. This can occasionally result in an abnormally loud engine due to the fan operating at full power. When the engine is cold or hot, the sound may be present at all times.

A Decrease In Acceleration, Power and Fuel Efficiency

Another sign of a defective fan clutch is a reduction in performance. A faulty or failed fan clutch keeps the fan constantly engaged, resulting in a loud engine and reduced performance. More significantly, a jammed fan clutch can generate excessive, unneeded drag on the engine, resulting in a noticeable loss in acceleration, power, and fuel economy.

Read more: How Long Can You Drive A Car With A Knocking Engine? (Explained)

How To Check The Fan Clutch 

When the engine is turned off, you may do the following checks on the fan clutch:

  1. Spin the fan – While electronic fan clutches may freewheel, most fan clutches should spin with little effort. If the fan spins more than three times, you may have a faulty fan clutch, and if the fan does not spin at all, the bearing may be seized.
  1. Wiggle the fan – by moving it forward and backward. If it clicks or wobbles more than a quarter-inch, it might be a worn bearing.
  1. Inspect for leaks – The fan clutch’s heavy silicone fluid or oil is essential to its operation. Because silicone oil’s viscous characteristics allow for gentle engagement to drive the fan, if it seeps out, the clutch would weaken and finally fail.
  1. Check the fan speed – It is audible when the fan clutch engages, accompanied by a blast of air. A thermal fan clutch should activate at a specified temperature as engine temperature rises, and torque-limiting fan clutches should disengage at certain engine speeds.
  1. Scan tool – To troubleshoot electronic fan clutches and the sensors used to determine fan engagement, some basic understanding of a scan tool as well as electronic testing may be necessary. If you lack this information, we at Diesel Components, Inc. can assist you in fixing your fan clutch quickly.

The internal combustion engine creates a lot of heat, and the engine cooling system, including the fan clutch, is primarily responsible for controlling it. A little heat is beneficial since it improves performance, fuel vaporization, and fuel efficiency while also warming up the cabin in the cold.

On the other hand, excessive heat can render lubricating oil ineffective and melt non-metal engine parts. An overheated engine may also weld itself into scrap metal.

You now understand that the fan clutch is one of the key cooling system components and is critical to the engine’s correct performance. When it fails, the engine faces significant damage from overheating. Replace your fan clutch as soon as possible if it is damaged or fails to prevent engine damage.


Turbo fanatics, as well as non-specialists, are aware that their vehicle’s radiator relies on steady airflow to spread coolant. Without sufficient airflow, the air surrounding the radiator becomes stagnant and overheats, preventing the engine from cooling. Fan clutches are an important part of this cooling system because they govern the functioning of an engine cooling fan by transferring energy from the engine fan belt to the fan and allowing it to revolve at a specific speed, therefore cooling the engine.

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