Should air be coming out of my radiator?

Author: Prof. Adrian Bogisich V  |  Last update: Saturday, September 6, 2025

Air pockets in the cooling system allow heat to build up causing extreme hot spots which can damage your engine. Air can get into your radiator, especially if the coolant level is too low or if you've recently drained it. Bleeding your radiator is necessary to remove the air.

Why is there air coming out of my radiator?

If your radiator isn't pitched properly, this water becomes trapped in the bottom of the radiator, and the next time the steam system turns on, steams shoots through the pipes and pushes this water out through the closest opening, which happens to be your air vent.

Should there be air in my radiator?

There is always supposed to be some air in the coolant jug to allow for expansion. As long as the coolant is filled to the cold mark when the car is cold it should be fine unless it is overheating or leaving traces on the ground.

Is a radiator fan supposed to push or pull air?

Before taking the car for a long drive, make sure you've wired the fan correctly so it is pushing air through and not pulling air out.

Why is my radiator releasing air?

If your radiator isn't pitched properly, this water becomes trapped in the bottom of the radiator, and the next time the steam system turns on, steams shoots through the pipes and pushes this water out through the closest opening, which happens to be your air vent.

How To Easily Bleed A Radiator

Is it bad if my radiator is hissing?

A faint hissing noise might also signify that your thermostatic valves are doing their job by moderating water flow into the radiator. Hissing sounds accompanied by banging, thumping, or other louder sounds are more alarming and should be checked by a heating engineer.

Why is there air in my radiator but no leak?

There are a number of reasons that cause air to build up in your radiators. Installing the pump above the supply tank. An open tank in the loft used for immersion heaters. A build-up of hydrogen in the system caused by a rusty pipe or a build-up of sludge.

How can I tell if my radiator fan is working?

There are a few ways to test the radiator fan. You can connect the radiator fan to the car battery with jumper wires to see if the fan runs normally. You can connect a low impedance lamp in series with the motor, turn it through, and see if the lamp ever goes dark, which is the most sensible way.

Should the fan pull air in or out?

You should place outward-facing fans on the warmer side of your home to blow the hot air out and inward-facing fans on the cooler side to draw cool air in, says Barry Jacobs, vice president of product development at Comfort Zone, a home environment product company.

What causes air to flow through radiator?

Air can enter your engine's coolant system through a leak in any component, including hoses or seals. See a qualified mechanic who can accurately diagnose problems with your radiator cap, thermostat, water pump, or hoses based on their knowledge and experience servicing similar parts on other cars.

How to burp a car radiator?

5 steps to bleed the air from your car radiator
  1. Turn off the engine. Your engine needs to be completely cool before you begin. ...
  2. Remove the radiator cap. ...
  3. Top up your coolant system. ...
  4. Run your engine and burp the coolant. ...
  5. Shut off the engine and top upof the coolant.

Should there be air in a radiator?

Most radiators will have a small amount of air in them, especially over time but even during the course of the heating system or radiator installation, some small bubbles of air may creep into the system. They can be created when your radiators are initially filled with water and a little air may remain in the system.

What are the symptoms of a bad water pump?

6 signs your water pump is failing ​
  • Coolant Leak. The water pump has several gaskets that can be damaged or worn out over time. ...
  • Engine Overheating. ...
  • High Pitched, Harmonic Whining Noises. ...
  • Water Pump Rust and Corrosion. ...
  • Steam comes out from under your hood. ...
  • Holes or leakage system on the dry side of the water pump.

What happens if you don't bleed air from radiator?

Over time, air can become trapped within your radiators, leading to cold spots and a less-than-optimal performance from your home heating devices. If you don't bleed your radiators, the issue will worsen over time.

Which fan direction pulls air?

The ceiling fan direction in summer should be counterclockwise to help create a downdraft, which creates that direct, cooling breeze. Your fan direction in winter needs to be clockwise to create an updraft and circulate warm air around the room.

Why is my fan blowing backwards?

Faulty Capacitor

If the capacitor isn't working, the fan won't get the boost of power it needs to start up and run, and the fan can spin backwards.

How to tell if a radiator is working?

Engine Overheating

The most obvious sign that your radiator is damaged is if your car overheats frequently. If the temperature gauge in your vehicle is rising higher than usual or if the engine warning light comes on, these are both indications that your radiator needs to be checked out.

Should my radiator fan come on?

Your radiator fan should kick in at about 200 degrees Fahrenheit. If you notice your vehicle is overheating or at the very least running hotter than it normally does, listen for the fan to see if you can hear it.

How much does it cost to replace a radiator fan?

Replacing a radiator fan typically costs between $50 and $500. Prices vary depending on brand and inclusions. You can tell a radiator fan is bad if it doesn't turn on, if the air conditioner doesn't work, or if it makes loud whirring noises.

Why is my radiator blowing air?

Common causes of air in radiators: Low water pressure, leaks in radiators, and heat pump problems.

How do I know if my air is trapped in my radiator?

Even a small amount can create air pockets which prevents proper circulation of coolant. Signs and symptoms of radiator airlock include: Overheating during normal driving. Heater not functioning correctly.

What happens if too much air in radiator?

If your central heating radiators aren't heating up as they should be, or you can hear bubbling noises, there may be a build-up of air in the central heating system. When this happens, the radiators can become much less efficient, which isn't ideal, particularly in the winter months.

Previous article
Should a fridge be silent sometimes?
Next article
Do I need an air purifier if I have AC?