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Lexus IS: How to Flush Radiator

The radiator in your Lexus IS regulates your engine's temperature. By flushing your radiator every 12 months, you will protect your radiator from rust or debris build-up that can lead to a clogged cooling system, which in-turn could cause your engine to overheat.

By Bart Kempff - November 11, 2014

This article applies to Lexus IS 250, IS 350 (2005-2014).

The radiator is one of the most important parts of your Lexus IS because it helps to keep your engine running at the correct temperature, especially in hot environments. Over a period of time, rust and other debris can get into the radiator causing it to work less efficiently. When the radiator is blocked or not working at its optimal rate, your engine can overheat, causing serious problems with the performance of your Lexus IS.

Tools Needed

  • 2 disposable radiator pans
  • 2 gallons of Toyota Super Long Life Coolant
  • 3/8'' piece of tubing
  • Bucket
  • Safety goggles
  • Protective gloves

Pro Tip

Before starting, make sure the Lexus IS has not been operated for at least 2 hours. The engine retains a lot of heat, so that should give it enough time to cool down. Draining hot coolant (or oil for that matter) from an engine is a second-degree burn waiting to happen.

Step 1 - Open hood

Open the hood of the Lexus IS, and make sure that it is properly secured.

Figure 1. Open and securely prop up the hood.

Step 2 - Drain radiator and engine block coolant

Locate the radiator drain plug at the bottom of the radiator. This plug is typically white. Center the radiator pan directly below the drain plug, which some vendors and manuals may also call a "petcock". Make sure you put on your safety goggles and protective gloves before pulling the radiator drain plug, letting the antifreeze drain into the disposable pan. Wait for the radiator to completely empty out. Then cover the pan and put it in a safe place. Draining the radiator will only clean out some of your coolant. To complete the job, you'll have to drain the coolant from the engine block, too.

  • Figure 2. Coolant bung diagram.
  • Figure 3. The port leaking pink fluid is the coolant drain. Remove the plug for this on each cylinder bank.

Pro Tip

Please bear in mind that antifreeze is very harmful and potentially deadly to children and animals. After all of the antifreeze has been drained from the radiator, make sure the disposable pan is properly sealed, and return the used antifreeze to a local auto parts store for proper disposal.

Step 3 - Attach hose to drain coolant from block into bucket

Take a 3/8" piece of tubing and connect it to the coolant drain port. This way, the coolant will flow out of the block and into a bucket.

Figure 4. Cleanly drain the coolant to a bucket by using a hose.

Step 4 - Refill with coolant

Replace the radiator drain stops, and then remove the radiator cap. Fill your IS with Toyota Super Long Life Coolant until it reaches the full line.

Figure 5. Use Toyota Super Long Life Coolant only.

Step 5 - Burp coolant system

There will likely be air in the coolant system at this point, which is not ideal. To fix this, squeeze the radiator hoses a few times by hand. Check the coolant level and add more. At this point, you should have enough coolant in your engine to turn it on. Run the motor until the thermostat opens (your temperature gauge will stop moving). Keep the engine speed at 2,000 rpm or so for a few minutes before turning it off and letting the car cool down. Check your coolant level one more time and add more if necessary.

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