Why is my radiator fan so loud

Q: I have a 2016 BMW 528i. The fan motor is very, very loud. BMW tells me they have had problems with some of the 5 Series fan motors. Since this noise doesn't come up on an error code they won't fix it. Now when my car is idling in warm weather it sounds like a junk car. I am thinking of just getting rid of the car. Shame on BMW for knowing about this problem, but refusing to address it. — R.M., Chicago

A: This sounds like your fan might be running at maximum speed in an attempt to prevent overheating. If your coolant temperature is normal, there may be a problem somewhere in the cooling system giving the control module bad info. It could be a coolant temperature sensor, a water pump sensor, air conditioning command for more airflow, or even a failing water pump. Leave diagnosis to a trained professional technician.

Q: My 2002 Dodge Caravan has trouble starting, mostly after the car has been standing overnight. It may require two more attempts until it starts the motor. I'm being told I need a new starter motor, which is expensive for the part and for the installation. I have been willing to put up with this difficulty, especially when it only shows up on the first start of the day. Someone advised me to tap on the starter motor with a heavy tool and it works. I have put up with this for several months now and though it is annoying, I can live with this as long as it does not get worse. Are there any fixes other than a complete replacement of the starter motor? — S.W., Morton Grove, Ill.

A: There are no fixes other than replacement. When the starter motor stops spinning, it comes to rest on a dead spot on the armature. Rapping on the starter nudges it just enough from that position. Eventually, you will either tire of whacking the starter (winter is approaching, ugh) or the starter will quit responding to your persuasion.

Q: In your recent response about bleeding tire pressure you recommended starting the day of a trip to the inflation pressure on the door placard. What about the situation where you are traveling across the country from the Midwest to the Southwest in the winter? On a recent trip to Scottsdale, Ariz., from Chicago my tire pressure went way up in warmer temperatures. Does it make sense, if you don't have access to an air compressor, to inflate your tires a bit more than the inflation placard in the evening and then recheck and bleed if necessary the next morning before driving the car? — G.R., Chicago, Ill.

A: Tire pressure increases or decreases by about 1 pound per square inch for every 10 degrees of change in the ambient temperature. That is why it is important to make adjustments from season to season, or in your case, from latitude to latitude. Tire pressure should be checked and adjusted when the tires are cold, after the car has been sitting overnight or several hours. It is OK to drive about 5 miles or so to the nearest station if you don't have an inflator.

Send questions along with name and town to Motormouth, Rides, Chicago Tribune, 435 N. Michigan Ave., Fourth Floor, Chicago, Ill. 60611 or .

Radiator fans come in many shapes and sizes and are used in different applications. However, radiator fans can break which will cause different kinds of noises depending on the type of radiator and the problem. 

Radiator fans can cause noise when they are not working correctly. This can occur for several reasons, including a broken or loose fan blade or a motor that needs to be replaced or repaired. It is necessary to determine why the radiator fan is making noise to fix the problem. 

In this article, I will explain some common causes of radiator fan noises and some noises to watch out for. I will also give you tips on how to fix the issues and when to take the car to a mechanic.

6 Causes of Radiator Fan Noise

A few different things can cause noise from a radiator fan. However, the most common problem is the fan wearing out. 

If the fan has any problems, it may cause it to run louder than usual or make other strange noises. Another possible cause of the noise is something wrong with the wiring of your car’s electrical system. 

For example, if the fan is damaged or worn, it may scrape against the radiator shroud or housing. This can result from wear and tear or damage caused by an object such as a rock striking a fan blade. Sometimes, loosened bolts can cause a fan to vibrate in its mounting system and create noise. 

Here are the common causes of radiator fan noise: 

1. Loose Fan Clutch

The fan clutch controls the speed of the radiator fan by turning it on and off as needed so that it is not running all of the time. The fan clutch can wear out over time and begin to make a rattling noise when it fails. It is recommended to replace your radiator fan clutch every 80,000 kilometers (49,710 miles). 

Read: Radiator Fan Replacement Cost

2. Broken or Damaged Radiator Fan Shroud

The radiator fan shroud is designed to keep the air flowing through your radiator fins. When the fan shroud or any part of it becomes broken or damaged, it can cause your radiator fan to become unbalanced and make a rattling sound. It is recommended to replace your radiator fan shroud if there is any damage or missing parts. 

3. Worn Bearings

Radiator fans are mounted on bearings or bushings, allowing the fan to spin freely without making much noise. Over time these bearings can become worn out, causing them to chatter and become noisy and should be replaced as needed. When the fan bearing is worn out, it causes metal to metal contact. This will make the fan very noisy. 

4. Broken Fan Blades

A clunking noise usually means one of the fan blades is broken. This is probably because the fan blade is made of plastic and has snapped off through fatigue. Driving with a broken fan blade can be dangerous, so you should replace the blade right away.

5. Loose Fan Motor Mounting Bolts

If the fan is loose on the mounting, it can vibrate against the radiator and possibly rub on other components such as the fan shroud or hose. If your fan is vibrating or shaking violently, you should tighten the mounting bolts holding the fan motor in place. 

6. Bad Fan Motor Brush Assembly

If your fan makes a low hum and does not spin at all, it is probably due to a broken motor brush assembly. The motor brush assembly is the component that conducts current between the wires and the moving parts of the fan. The only solution to this issue is to order a replacement assembly.  

Read: Why Radiator Fan Is Not Working?

Two Types of Radiator Fans

There are two types of fans: 

• Mechanical. Mechanical fans have belts that run off the engine’s crankshaft and cause the fan to turn. They have been used for decades but have been phased out, favoring electric fans, which are quieter, more reliable, and more efficient. 
• Electric-driven. Electric fans use an electric motor to turn on and off, and are most common in modern cars and SUVs because they save fuel. However, electric fans can cause noise when they are not working correctly. 

Read: Why Radiator Fan Always On?

Identifying Noises From an Electric Radiator Fan

The noises from an electric radiator fan vary from mechanical fans. However, the difference is dependent on the problem with the fan. 

It is essential to know what kind of noise is coming from your car. Here are some common problems and their noises: 

Rattling or Clicking Noise

A rattling or clicking noise signifies that the bearings are worn out in your electric radiator fan motor. It may also mean there is debris between the blades on your electric radiator fan blade, which is a common issue in any fan. 

Squealing Noise

Squealing noises are unique to electric fans and sound similar to a failing tensioner pulley system. This means that the pulley or belt on your electric radiator fan motor needs to be replaced or re-adjusted. 

This can also mean that you need a new engine cooling system because there is no refrigerant left in it, which causes friction between metal parts. The metal parts can wear out fast because they rub against each other when running an engine through cold weather conditions like snow blizzards. 

Radiator Fan Noise Repair

To repair the radiator fan, you will need to remove the fan and fit a different one. If you’re removing a viscous-coupled fan, you will also need to replace the viscous coupling. 

Noise from a radiator fan can also be resolved by repairing or replacing the engine cooling system components. A certified mechanic should repair or replace these parts for you. 

However, if your cooling system has failed along with the fan, simply replacing it is not enough to keep the car’s engine running normally again. For this, it’s highly recommended to take your vehicle to a professional who can safely replace your car’s cooling system. 

The Job of the Radiator Fan

The radiator fan is located in front of the radiator and blows hot air out of the engine compartment. The job of the radiator fan is to circulate air over the radiator to help cool the engine. 

While your engine is running, the coolant circulates from your engine through the radiator at the front of your car where it is cooled off by air flowing through the fins on top of and beneath the radiator. The temperature of this coolant can determine whether or not your car overheats. If the coolant gets too hot, you run the risk of damaging internal engine parts, such as your pistons. 

When airflow through the radiator is not enough to keep it cool at idle or low speeds, the fan comes on to help cool down the system. 

The radiator fan has two main functions: 

• To assist in cooling off the radiator when the car is moving slowly or stopped. 
• To draw in the fresh air that carries away heat from the condenser when the air conditioning is on. 

Read: Why Radiator Fan Goes ON and OFF?

Fan Has Stopped Working

If your car is overheating and the radiator fan has stopped working, there is a good chance that your problem is electrical. Radiator fans turn on when they get a signal from their respective temperature sensors, either coolant or air temperature.

If the fan isn’t working, it could be a blown fuse, bad relay, or a broken fan motor. 

Read: Why Car Overheats?

Conclusion

Radiator fans can fail without appearing to be damaged. Electric and magnetic forces can cause the fan to move or vibrate, which can make a noise. 

Loose screws and bolts may cause the radiator to make a rattling noise. The noise may simply stop once the fan is no longer in contact with any wires or other parts. 

Additionally, your fan may have a broken blade or a worn bearing causing it to make noise.

However, if the issues are more severe, a full replacement will be needed.