Balancing Act

DIY: How to Exchange the Engine Coolant On Your 3rd Gen Prius

Before you proceed with this maintenance procedure, make sure you have access to a flat and level surface area. You will also need two jack stands to support the front end of your car so you can gain access to the inverter coolant drain plug.

Toyota recommends inspecting and topping off the inverter coolant reservoir every 5,000 miles and a complete drain and replace every 100,000 miles. So I’m 20,000 miles late to the game.

My local Toyota service center charges $159.95 for this procedure. If you do it yourself, material cost is between $26.00 ~ $52.00 for two 1 gallon jugs of Toyota’s Super Long Life Coolant (SLLC), depending on where you acquire them.

I only used up one gallon jug for this engine specific service, but it’s good to have extras (2) on hand if you intend to also exchange the inverter coolant and to top off every 5,000 miles.

In addition, you’ll need a hydraulic floor jack, 2 jack stands, drain plug gasket, ratchet with a 10 mm hex bit and a drain pan. A creeper will also make the job easier and keep your back clean.

The entire engine coolant fluid exchange service takes about an hour of your time, including waiting for the old coolant to completely drain.

Tools and Materials Needed

Toyota’s Super Long Life Coolant lasts an incredibly long time and comes pre-diluted, meaning it is ready to use right out of the jug. You do not need to pre-mix it with water as you would with the traditional green stuff from the local auto supply store. You will need at least one gallon, but having two jugs on hand just in case is never a bad idea. Regardless, it’s a good idea to have an extra jug laying around in the event you need to top off the coolant reservoir.

Removing the Engine Under Cover

Because you’ll be working underneath your car, safety goggles are an absolute necessity. Do not attempt unless you are wearing a pair.

Working on a flat and level surface, place wheel chocks on the rear wheels and then jack up the front of the car. Place a jack stand on each front jack support on the chassis.

In order to access the engine coolant drain spigot, you’ll need to remove the engine under cover. This involves removing six 10 mm bolts and 13 push-pin retainer clips. If the clips are worn and brittle, this would be a good time to replace them.

Removing both clips and bolts should take you approximately 15 minutes if it is your first time and subsequently quicker. This is what the cover looks like and where the bolts (yellow) and clips (red) are located to visually help you expedite the removal process:

Since removing the engine under cover is an involved procedure in itself, you might want to consider performing these maintenance service at the same time if possible:

Doing all aforementioned services together should take you approximately 3 hours.

Exchanging the Engine Coolant

Believe it or not, the hardest part of this maintenance procedure is done. The following steps should take you approximately 30 minutes.

Step 1

Remove the cap on the engine coolant reservoir and set aside. Locate the engine coolant drainage spigot.

It is located on the driver side, close to the driver side head lamp and just behind the radiator. Reach behind the lower chassis frame until you are able to reach the yellow valve behind the engine coolant drainage spigot:

Place your drain pan directly beneath the spigot then turn the valve counter-clockwise slowly until the coolant begin to drain. Open up the valve completely.

Step 2

Let the engine coolant drain completely. This took me about 10 minutes. Once the engine coolant stops dripping from the drainage spigot, close up the drainage valve and replace the engine under cover.

Step 3

You should empty approximately a little over a jug’s worth of spent engine coolant (photo shows volume of both engine and inverter coolant drained and combined):

Step 4

Place a funnel over the engine coolant reservoir and begin filling. Fill to the FULL line and then let the fresh super long life coolant drain into the engine coolant system.

Repeat until the engine coolant remains at the FULL line.

You will probably fill and wait a total of three to five times before the coolant in the engine coolant reservoir stops draining.

Step 5

Get your car into maintenance mode so that only the internal combustion engine (ICE) is activated, disabling the hybrid drive system. You need to do this to ensure the engine coolant travels through and fills up the engine coolant lines and system. To get into maintenance mode, press the POWER button, brake pedal, gas pedal and drive control in the following sequence:

  • With the car off, press POWER twice to activate accessory mode
  • Press the GAS pedal completely, twice
  • Press and hold the BRAKE pedal while shifting into NEUTRAL
  • Press the GAS pedal completely, twice
  • Press the PARK button
  • Press the GAS pedal completely, twice

Once in maintenance mode, get the Prius into READY mode by pressing and holding the BRAKE pedal while pressing the POWER button. The ICE should start immediately.

Getting the Prius into maintenance mode forces the car to continuously run on the internal combustion engine, which only happens when the car warms itself up or if you are accelerating, therefore forcing the engine coolant system to activate and circulate coolant. The ICE will continue to run until the car is turned off.

Step 6

Let the car idle for 5 minutes then turn on the heater to HI and set the fan to full. The radiator fan should activate. Allow the system to run for an additional 5 minutes.

Observe the engine coolant reservoir to ensure that the coolant level does not drop below the FULL line. If it does, top off with additional coolant.

Step 7

Get out of maintenance mode by restarting the car. Take the car for a drive around the block to fully activate the coolant system. Park your car and take note of the coolant level in the engine coolant reservoir. It should remain on the FULL line. If it dropped, top off. Check for leaks.

7 thoughts on “DIY: How to Exchange the Engine Coolant On Your 3rd Gen Prius

  1. Ryan Will

    Thank you kindly for your post on this!
    In addition to the coolant, I replaced the water pump and thermostat, as they were fairly easy to do at the same time.

    The issue I am having now is my radiator fans never came on during the bleeding procedure. The temperature, per an OBD scanner, never topped 201°F and the coolant appeared to be circulating in the reservoir.

    Hoping it still bled the air out properly, as I have yet to take it for a test drive (just did it today as of this writing).

    Again, thank you for your time!

  2. Austin

    Very good tutorial , glad i found this answered a lot of my questions on how to change 2011 Prius fluid (DYI) and more so on putting cat in maintenance mode . thanks for posting
    Saved me $400 dollars from dealer.

  3. Mario Figeac

    I liked your instructions better than that of the mechanic on Nutz and boltz video. It helped me a lot to follow your instrucctions without a video. Great instructions

  4. John

    These are great tutorials. They should sticky it on priuschat. The inverter fluid and engine coolant are the same fluids. Do you need 1 gallon or 2, if changing both?

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.