Fun Fun Fun at the Dealer: Engine Coolant Flush

The Prius can be difficult to fully bleed the air out of.

I checked my All Data and it does appear the inverter and engine are separate loops.

For the engine, you're supposed to use the Toyota scantool to command the coolant transfer pump to run, to assist in bleeding air

The inverter loop is easier to bleed. The shop manual suggests running a clear plastic hose from the inverter bleed screw into the inverter coolant tank. Slowly add coolant to the inverter tank until the coolant in the clear plastic tube matches the level in the tank

This is the old fashioned way of making a level

For the inverter, the manual suggests a few power on/ power off cycles until the pump noise is smooth. The manual also states the pump may sound very rough at first, as air is forced out

Regarding chemical flushing, there are machines out there that will inject cleaning solution and soft water into the cooling system to remove rust, scale, etc, then properly refill with fresh premixed coolant

These machines are pretty expensive though. It's like transmission fluid exchange machines, most dealerships don't have them. For a conventional automatic, they'll at most do a pan drop. If the trans fails, they see $$$.

 

It ought to go faster in winter, assuming that you use the cabin heat, because then the heater core gets circulated also. Top off as needed, obviously using only the correct Toyota fluid.

 

Hopefully. Keep an eye on the level in the coolant tank

 

The inverter/transaxle coolant loop is definitely separate from the engine coolant loop.

My post #6 in the following string explains a DIY method to purge air out of the engine coolant loop. Persistence is required especially with 2G NA vehicles that have the coolant heat recovery canister and the pump that only runs at startup and shutdown.
http://priuschat.com/forums/care-maintenance-troubleshooting/58814-preventative-maintenance.html

Since the 2G maintenance schedule indicates that the first coolant service is at 100K miles, my guess is that most Prius techs don't have much experience performing this service on 2G. How else to explain why so many posters report air in the engine coolant system after having this work done at a Toyota dealership.

 

There simply is no reason to return a car to the customer scratching your head wondering if you got all the air out of the radiator when there's so many tools available to do just that:

MityVac - Automotive Vacuum Pump Kits - Radiator Adapters - Cooling System & Pressure Testers Kit - Fluid Evacuator

I cannot believe there's a Toyota dealer on the planet that doesn't have one of these tools. This ain't rocket science. Unfortunately your dealer failed that test on a very simple procedure and I would not let them get my hands on my Prius again. They just simply suck.

Now your car. Backyard fix is to elevate the front of the car..jack it up....take the rad cap off and let it run for a while with the heater on. Eventually the air will will forced out by gravity. Its the height of the motor above the rad that airlocks you.
Good luck.

 

That's a problem with a lot of newer vehicles in that with the vehicle on level ground, the motor is a bit higher than the radiator. Almost impossible to properly bleed the Old Fashioned Way

Yep, there are tools that assist with bleeding air. Scary to realize that a Hybrid "certified" Toyota dealership can't figure this one out

 

DH never used a vacuum refill tool on a prius either. he's got one, just never put it on a prius.

 

The capacity of the NA 2G engine coolant system is ~9 qt. However after opening all three drains I was able to get 6 qt out. If you refill with SLLC, run the engine for a while, then drain the coolant out again, this will replace ~90% of the original coolant. Since you were charged for 3 gallons of coolant, my guess is that your tech used a similar process.

I don't think you would want to flush using water, because if you did so you'd end up with a substantial amount of water in the system at the end of the day (since SLLC is premixed with water.)

To encourage coolant flow and get air out of the system, it is helpful to rev up the engine (speed is limited to 2,500 rpm in inspection mode) and to open the vent on top of the radiator (near the driver's side.)

Yes, you might think that the dealer techs should be able to do a better job than a DIYer since they have access to the correct equipment and training. The difference is that the DIYer presumably cares about the vehicle in question and is motivated to do a first-class job since his/her personal safety depends upon that work. Sometimes its not obvious that the dealer techs possess a similar degree of motivation.

 

Last paragraph: Exactly to the point

 

Here is the tool I use and is used by many shops to bleed the air from the radiator. You will also need an air compressor to provide the air for the tool.http://www.amazon.com/dp/product/B0002SRH5G?tag=priuschatcom-20