How to Replace a Radiator Drain Plug

April 10, 2012

If you keep replacing coolant without spotting a rupture in the radiator, replacing the radiator drain plug should be your first course of action.

Radiator Drain Plug Replacement

Many times a leaky radiator can be attributed to a damaged radiator drain plug. Sometimes, a drain plug can be damaged when being removed or reinserted or even by a rock that strikes the plug while you are driving. Replacing a bad radiator drain plug is a simple task and can be done in a few minutes.

Tools and Materials

  • A new radiator drain plug
  • Wrenches or screwdrivers
  • A plastic bucket or container
  • New coolant

Allow Car Engine to Cool

When you get home, allow your car's engine to completely cool before working on the radiator. You should always make sure the car engine is completely cool in order to avoid a serious burn or injury when working with your car's cooling system.

Locate Radiator Drain Plug

Next, find your car's radiator drain plug. In most cases, the drain plug is located on the bottom of the radiator itself and is usually a plug with a bolt or screwdriver head that needs to be removed in order to drain the radiator. In some cases, the drain plug may be on either side of the radiator located near the bottom.

Remove the Radiator Drain Plug

Before removing the plug, put your plastic bucket in place, as the coolant in the radiator will flow out as soon as you remove the plug. Using a wrench or screwdriver of the appropriate type, remove the radiator drain plug.

Install New Radiator Drain Plug

After all of the coolant has drained out, install the new radiator drain plug. When tightening the new plug, make sure is secured tightly—but make sure not to over tighten. This may cause damage to the new radiator drain plug.

Refill Radiator with Coolant

Refill your car's radiator with a mixture of 50 percent antifreeze and 50 percent water. This is the mixture appropriate for most parts of the country. If you live in a particularly cold climate, use a mixture of 70 percent antifreeze and 30 percent water when filling your radiator.

Check for Leaks

Start the engine and carefully observe the bottom of the radiator for leaks. If there are no apparent leaks, you are finished. If there are leaks, turn off the engine and check that the new drain plug has been inserted correctly and is tightened securely.

Dispose of Old Coolant

Take the old coolant to a recycling station or local auto parts store that accepts fluids for recycling. Never pour old coolant down the drain or on the ground, as this is very harmful to our environment.

Finding the Radiator Drain Plug

Here are a few tips on how to find the radiator drain plug on your vehicle.

Look on the Bottom of Your Radiator

Many vehicles have the radiator drain plug installed at the very bottom or underside of the radiator. The radiator drain plug may appear to be a screw-in type plug, that has a screw head or a T-bolt head. This is the most common location for the drain plug on a vehicle. You'll probably have to crawl underneath the engine in order to access the drain plug.

Radiator Removal May Be Required

On some vehicles, the radiator drain plug is located on the side of the radiator near the bottom edge. However, in many vehicles that have this type of radiator drain plug configuration, the mounting bolts for the radiator may need to be removed and the radiator slightly turned at an angle in order to reach the drain plug.

What If No Drain Plug Is Available?

Some of car manufacturers choose not to install a radiator drain plug at all. If you want to drain the radiator fluid on a vehicle with no radiator drain plug, you usually need to disconnect the lower radiator hose and drain the fluid that way.

How to Replace a Radiator Drain Plug O-Ring

When replacing the radiator fluid, or having your radiator flushed, it's a good idea to replace the O-ring on the radiator drain plug as well. Over time, the O-ring can become damaged, resulting in a radiator leak.

Tools and Materials

  • A new O-ring
  • Work gloves
  • A dry towel
  • A screwdriver or wrench
  • Vaseline or silicon lubricant
  • A bucket or plastic container

Turn off the Car Engine

Before attempting to work on your car's cooling system, always make sure that the car engine has completely cooled down. It may take several hours for your car engine to cool completely; however, you never want to work on the radiator while the engine is hot because you may be seriously burned or injured.

Loosen and Remove the Radiator Cap

While wearing your gloves, place the dry towel on top of the radiator cap. Slowly turn the radiator cap counterclockwise until the spring disengages and pressure starts to escape from the radiator. Do not remove the radiator cap completely until all of the air or pressure has escaped from it.

Drain the Radiator

Place your bucket or plastic container underneath the drain plug of your radiator. Use the screwdriver or wrench to turn the drain plug counterclockwise and remove it. Allow the old radiator fluid to drain into the container and set it aside.

Remove the Old O-Ring

Apply a little Vaseline or silicon lubricant to the old O-ring and slide it off of the drain plug.

Install the New O-Ring

Apply a small amount of Vaseline or silicon lubricant to the new drain plug O-ring and slip it onto the drain plug. Make sure that you push the O-ring into place completely, and make sure that it fits in the groove for the O-ring correctly.

Replace the Drain Plug

Reinsert the drain plug into the radiator and turn it clockwise to tighten it. Make sure that the drain plug is tightened securely, but do not tighten it too much, as the drain plug may break.

Add New Coolant

Add a mixture of half antifreeze and half water to your car's radiator. Fill your radiator with the mixture until it is completely full. If you have an overflow reservoir tank, fill that with the mixture as well.

Burp the Radiator

Leave the radiator cap off of the radiator and start the engine. Allow it to run for several minutes to bleed any air out of the cooling system.

Add More Radiator Fluid

Add more antifreeze coolant and water and top off the radiator and the reservoir tank.

Replace the Radiator Cap

Reinsert the radiator cap into the filler neck of the radiator and turn it clockwise until it's tightened securely.