Car Smells Like Burning Rubber When Heater Is On – 6 Reasons

Besides keeping you and your passengers comfortable, your car’s heater sometimes helps protect the engine from overheating. 

But what does it mean when the car smells like burning rubber when the heater is on? The burning rubber smell in your car when the heater is on can mean many things, including a leaky heater core. It could also mean the cabin air filter is clogged or the drive belt is worn-out. Sometimes, the smell could be due to

• Blocked radiator, leaking valve cover gasket, or damaged resistor

So then, what is the solution to this problem? Read on to find out this and much more. 

Causes Of Car Smelling Like Burning Rubber With Heater On Table

Here is a quick summary of why your car may smell like burning rubber when the heater is on and the solutions. 

Causes	How To Fix
Leaking heater core	Seal the leak with a sealant add-in
	Replace the heater core and add coolant
Blocked radiator or radiator fan	Clear the blockage using radiator flush and water
Bad blower motor resistor	Install new resistor
Clogged cabin air filter	Clean or replace the filter
Leaking valve cover gasket	Replace the gasket and spark plugs
Worn-out serpentine belt	Replace the belt immediately

Why Does Car Smell Like Burning Rubber When the Heater Is On?- In Detail Discussion

Below, we will look at why your car may smell like burning rubber with the heater on and the solutions in detail. 

1. Leaky Heater Core 

The heater core is a small radiator designed to warm your car’s cabin using engine coolant. If the heater core is leaking some coolant, the coolant may burn and smell somewhere between burning plastic and rubber.

In most cases, you may smell the burning rubber only when the car is idle. And one of the symptoms of a leaky core heater is a damp carpet on the passenger side.

Additionally, some parts of the heater core made of plastic materials may melt, causing the burning rubber smell.

Solution

The best and most effective solution would be to replace the entire unit and top off the coolant if it is low. However, if the leak is minimal, you could fix the leaking with a sealant add-in. This is easier than doing the replacement.

2. Clogged Radiator or Radiator Fan 

Your vehicle’s radiator and the fan may get clogged up with debris or dust over time. Due to the clogging, your car’s radiator may have difficulties circulating the coolant. If the radiator fan is clogged, it will not push the hot air out of the engine.

As a result, the coolant will boil over, causing your car to overheat and produce a burning rubber smell. This smell usually comes from the sizzling coolant.

Solution

• Drain the radiator and pour some radiator flush inside
• Then, start the engine and allow it to run for at least 15 minutes
• After the engine has cooled off, connect a water hose inside the radiator, fill the cap and run water through your car’s cooling system. This should clear the blockage.

3. Faulty Blower Motor Resistor

The blower motor resistor is made of a combination of plastic and metal materials. Typically, this resistor controls your vehicle’s fan speed.

This resistor may occasionally overheat due to mechanical obstruction, debris, and water. Unfortunately, when the resistor gets too hot, it may burn and smell like rubber.

Solution

The only solution here is to replace the blower resistor in the compartment housing the AC and heater.

4. Clogged Cabin Air Filter 

Typically, you should replace your car’s air filter between every 15K and 30K miles. This is because the filter is prone to clogging up debris, dust, and dirt.

When this dirt build-up gets heated, it may cause a displeasing smell, including that of burning rubber. The burning rubber smell could also be due to the insulation on the wires burning or melting.  

Solution

You can either clean or replace the cabin air filter if it is made of carbon or cloth. To clean the filter, gently blow air through it or use low-pressure water. But if it is made of paper, you will have to replace the cabin air filter. 

5. Leaking Valve Cover Gasket

Over time, the valve cover gasket closer to the firewall may crack or break, or the bolts may become loose. This happens due to exposure to heat, dirt, and other elements.

As a result, the gasket may start leaking oil, and you may sometimes see smoke coming in from the vents. The leaking oil may eventually drip on the heat shields from the passenger side of your vehicle’s engine. And when you turn the heater on, the oil may cook up, producing a burning rubber smell.

Solution

You will have to replace the valve gasket cover with a new one. Also, you must change the spark plugs if the leaking oil from the gasket is pooling around the base of the plugs. 

6. Worn-Out Drive Belt

Your vehicle’s drive belt, also known as the serpentine belt, is primarily made of rubber materials. Its main job is to transfer power to various components of your car, including the engine cooling fan and AC.

If the belt becomes loose on a pulley, it may slip, leading to heat build-up from too much friction. Because of the excessive heat, your car may start smelling like burning rubber.

Solution

Replace the worn-out belt, which is easy and relatively inexpensive. Watch this video and learn how to change the serpentine belt: 

Tips To Prevent Burning Rubber Smell When Heater Is On

Now that you know what causes a burning rubber odor when the heater is on, how do you prevent it? Check out these tips.

• Always check your vehicle’s coolant level when the engine has cooled down. It should be between full and low marks.
• Inspect the engine regularly to ensure the gaskets, belts, and hoses are not worn out.
• Always look for any oil and coolant leaks around the engine compartment.
• Make sure to clean and change the air filter regularly, depending on your driving conditions.
• Check the radiator and radiator fan regularly for any dirt, debris, and dust build-up, and clean if any.
• Drive your car regularly. This will help keep the engine and all components adequately lubricated. 

If you’re dealing with a burning rubber smell in your car when the heater is on, you may also be interested in our articles on why your car AC smells like vinegar or why your car smells like rotten eggs. Our article on car AC smells like vinegar explains the possible causes of this smell, such as a dirty air filter, mold growth in the AC system, or a refrigerant leak. Meanwhile, our article on why your car smells like rotten eggs discusses the common causes of this odor, such as a catalytic converter that’s not working properly, a malfunctioning fuel pressure regulator, or a sulfur buildup in the engine. If you’re experiencing any of these smells in your car, our articles can help you identify and fix the problem

FAQs

Without further ado, let’s look at commonly asked questions regarding cars smelling like burning rubber with the heater on.

Bottom Line

Regardless of your car model or brand, you may occasionally experience a burning rubber odor when the heater is on. This may be due to the heater core leaking coolant or a clogged air filter and radiator fan.

Whichever the cause, the best solution is usually to replace the damaged component. That said, you should be pleased to know there are several ways to prevent this problem from occurring in the first place.