How do I drain the engine cooling system?

Prius 30k Service

 

100K maint - 5

 

I would suggest that you not flush the engine coolant system with water because it is hard to get all of the old coolant out. Since SLLC is premixed, by using water as a flushing agent you will end up with an antifreeze/water mix where the antifreeze proportion may be as low as 33%. Also, when you drain the old SLLC, you will probably find it is quite clean, no debris to speak of within.

Just measure the amount of drained old coolant and do not consider the job done until you have replaced with an equivalent amount of new coolant. Six quarts is about right.

It is a lot of work to remove the engine thermostat, if you don't plan to actually change it. See my thread below which also has a pointer to another thread discussing how to replace engine coolant given the presence of the coolant heat recovery system.

How to replace engine coolant pump and thermostat | PriusChat

Finally, I would have to say the Haynes manual is worthless if it doesn't even explain how to perform basic maintenance like engine coolant replacement.

 

This is the less expensive tool that you'll need to purge air out of the cooling system;



This would be the professional tool like the ones used by Toyota dealers.

 

The funnel allows you to raise the level of the coolant above the heater core. I have never used one as I have the air lift, but it seems easier and certainly cheap compared to the air lift.

 

Yes, if you start by draining from the CHRS canister (leave the radiator cap and overflow reservoir cap on during this process, so the reservoir fluid will be sucked out via vacuum) that will result in draining out ~95% or more of the total fluid. Then you'll find when you open the engine drain plug, a tiny amount of fluid will come out. When you open the radiator drain plug you probably won't see any more fluid.

The Lisle funnel allows you to establish engine coolant level a few inches above the radiator neck. That additional fluid pressure works very well to help get air out of the system. I have used that funnel and it works great.

Don't forget the radiator valve that can be opened to get air out of the top of the radiator. Use a 6 mm hex key.

 

I have and use both.

The UVIEW system requires an compressor and is faster.

The Lisle funnel takes a little longer, but it works just as well.

 

Here's a less expensive one with more features of the same Lisle funnel.

 

This caught my eye for sure. I have read everything that Patrick Wong has written here on this subject. After reading a bit about the above tool, it makes me wonder if the "average joe" should invest in one of these.

I do admit it seems expensive, however if it will do the job quickly without a lot of effort it seems like it be a worthwhile investment for a DIY Prius owner.

If anyone on this board has used this product on their Prius, I would appreciate feedback concerning it.

To me, it seems like a no brainer. But to others it may be a different story.

 

1. You will need access to an air compressor.

2. Considering that the Prius engine coolant needs to be changed for the first time at 100K miles; then 50K mile intervals after that, you might think about whether it is worthwhile to spend $100+ for that tool when other alternatives exist.

 

It certainly works better than trying to do it without one, but you have to buy extra coolant in order to keep the pickup submerged in fresh coolant and/or transfer the coolant into some other type of container, because the hoses curl and you don't always know if the pickup is submerged once the container gets low. Also, it's not perfect, I have had to "drive with the heater on high and refill" at least once to get the last little bits of air out. The hoses are not really long enough to make it easy for one person to use, one hand holds the stopper in the radiator, the other hand is balancing the fresh coolant container. If you have a helper it would make it easier.

While this setup can be used on other vehicles, the only type that I've needed to use it on is the Prius.

For next time, I'm going to try one of those big funnels and see how that works, if that tells you anything.

 

That helps a lot. I have a compressor, so that is not a big deal. And yes, it does make sense that you would have to have extra coolant.

I am surprised to hear that it did not get all of the air out as Joe wrote above.

With all that said, I would tend to believe that the Lisle Funnel that Patrick has wrote about would be the best option for the DIY guy if you are working on a Prius.

Thanks for the feedback guys. It is definitely appreciated.

 

The "coolant control valve" on my genII prius started throwing DTC's a few weeks after I had the inverter coolant pump changed under recall. I decided to change the coolant control valve and associated coolant myself to ensure the job was done right. I spent several days trying to patiently work air out of the heater core to no avail. After I found this thread, I bought the Lisles funnel, and the air was successfully purged within 15 minutes. Works great. Highly recommended.

 

I am getting ready to change the engine coolant in my 2009. I jacked the car up last weekend to get the lay of the land and I could not see a drain valve on the radiator. I see the drain valve that is next to the heat storage tank, but nothing on the radiator itself. The descriptions that I have read mostly seem to refer to a drain under te radiator---- Am I missing something? Will the drain by the heat storage tank drain the engine and radiator?

Any insight appreciated

Steve

 

As a matter of fact, the drain at the coolant heat recovery canister is the best choice of the three potential drains that you could use. If you open just that one drain, you will drain about 98% of the coolant that could be removed by also opening the engine block drain (~ 2% incremental) and the radiator drain (0% incremental). Of course, you will then need to refill the coolant heat recovery canister which requires manually running the CHRS pump.