This is the second part in a 2-part series showing how to bleed the ICE engine coolant in Prius Gen II. If you haven't watched Part 1 yet (Burping / Getting Rid Of Trapped Air in Coolant Heat Recovery System Tank Canister), please watch it here:    • Prius Coolant Bleeding Part 1: How To...  

This video is for Toyota Prius Gen II I4 1.5L Hybrid Synergy Drive. Second generation Prius model years are 2004, 2005, 2006, 2007, 2008 & 2009. Bleeding or burping on other generations Prius might be different.

When you drain the coolant, whether for scheduled maintenance or if you have had to replace components such as radiator, hoses and pumps, refilling the coolant is only the initial stage of a complicated process. The next step is to bleed or burp the cooling system to get rid of the present of the air pockets.

"Burping" the cooling system in your Toyota refers to bleeding the cooling system and is necessary if air has entered the system. Air in the cooling system causes hot spots and subsequently overheating and serious engine damage. Failure to bleed trapped air will result in the dreaded triangle of death followed by temperature icon on the instrument cluster and dashboard display. There might, however, not be any CEL or error codes.

Other than the triangle of death icon followed by temperature icon, symptoms of air bubbles in the system are as follows: When you turned the car on, and/or while driving you can hear the sound of water travelling in the engine compartment into the heater core inside the cabin. You'll hear "gurgling" , "wooshing", or "swishing" sound coming from the middle of the dashboard inside the car, which means there's trapped air inside the heater core.

Burping or bleeding trapped air is rather complicated because Generation 2 Toyota Prius Internal Combustion Engine (ICE) cooling system has a Coolant Heat Recovery Storage Tank Canister (CHRS). So before you can get ride of air inside the heater core, you must first get rid of the air inside the CHRS.

In the first part of the video as described above, young mechanic Aiman showed you how to remove the air pockets inside the CHRS by activating its pump by using relay to force coolant into Heat Storage Tank thereby removing any trapped air there. In that video, Aiman also explained what CHRS is, how it works, why it's there, its functions and purposes. CHRS rarely malfunctioned, but its pump may, and you might get DTC P1151 if the water sender temperature sensor is malfunction.

After CHRS has been bled, the next step is to remove trapped air (or air pockets) inside the heater core. This process involved turning the engine car on without driving it (putting in in test / maintenance / inspection / diagnostic mode), revving the RPM to 3000, turning the heat to max allows the radiator fluid to circulate through the cooling system to ensure that all air bubbles are eliminated from the system. Remove the radiator cap, insert a large funnel into the neck and the fill with coolant. After the engine has reached operating temperature and the thermostat opens, open the bleeder valve and squeeze the upper and lower radiator hoses. This is what this video is all about. In this video Aiman also showed how to do it even if you have an aftermarket radiator (with different style bleeder valve) as opposed to the genuine OEM one.

In order to bleed the air out of heater core, you will need to idle the engine / keep the engine running continuously. We have a separate video on how to to do that:    • How To Put A Prius Into Maintenance |...   (How To Put Prius Gen II in Maintenance or Inspection Mode).

Keep in mind that the Internal Combustion Engine (ICE) cooling system is separate and independent of the hybrid inverter cooling system, and if you want to know how to bleed the inverter coolant, check out our video here:    • How To Bleed INVERTER Coolant System ...  

The ICE cooling system uses the same type of coolant as the inverter cooling system. Gen 2 was factory filled with Toyota Super Long Life Coolant (SLLC). SLLC pink is premixed, eliminating the hassle of mixing and the potential for error. Toyota Super LongLife Coolant (pink) is just regular ethylene glycol silicate-free premixed Phosphate-based Hybrid Organic Acid Technology (HOAT / OAT). It is Silicate, Amine & Borate free. This genuine OEM manufacturer recommended coolant from Toyota dealership is rather expensive. Alternatives such as Zerex Asian, Pentosin Pentofrost A4 or other HOAT/OAT red/pink Super Extended Life coolant from Valvoline, Peak, Prestone etc., available at your local auto parts stores such as Advanced Auto Parts, AutoZone, O'Reilly, NAPA, PepBoys and even at Walmart -- can also be considered.

Thanks for watching and please watch other DIY and auto repair, how to remove, install, replace, repair and fix it ideas, guide, tutorials, and tools review videos on this channel.

Recording Date: November 29, 2018
Video URL:    • Toyota Prius Engine Coolant Bleeding ...