Coolant water storage tank- can't find it!

Hi David,

The UK models did not have the coolant thermos system, so It's possible that your version does not have it.

Regards,

Phil

 

The engine coolant heat recovery system is a North American 2G feature, like the fuel tank with the flexible bladder within. Be glad your car has neither of those features.

 

I believe you are correct. To drain the engine coolant, just open the two drain cocks: one on the engine block, on the side facing the firewall; and the other at the radiator. (North American models have a third drain cock at the coolant heat recovery system canister.)

Please keep track of the amount of drained coolant, and post. You also need to know the amount of drained coolant so that you'll know how much new coolant you need to add to the system before you can declare victory.

If you leave the radiator cap on while the engine coolant is being drained, that should create a vacuum which will suck the coolant out of the overflow reservoir.

The radiator has a valve on the top which you can open to let out trapped air, as you are adding new coolant. It requires a 6 mm hex key to open. After you remove the black plastic cover over the radiator, look for a hole in the sheet steel covering the radiator. That should be the location of the valve.

 

Would this be a good method to determine if the system is full? Many have a problematic seeping water pump (not knowing of course) this can reduce the level of coolant and if the removed coolant is the measuring method, it may be off when you refill.

 

The OP should consider he is blessed by not having the thermos bottle. It just creates more havoc when changing the coolant as he is doing. Only needed in USA to meet EPA spec's IIRC.

Agree with Patrick, measure out how much coolant comes out. You should refill with the same amount. Don't forget to bleed the air out of the system. Otherwise it will overheat.

Good luck to you davidls and Welcome to Prius Chat.

Ron (dorunron)

 

"...if the removed coolant is the measuring method, it may be off when you refill."

It is true that this assumes the radiator and the overflow container are both full, to start. If they are not, this should be accounted for when filling with fresh coolant.

Open the radiator cap as the first step, to see whether the radiator is full. Then replace the cap before draining coolant, so that the old fluid from the overflow container will be sucked out during the drain process.

 

I may be opening myself to ridicule, both for my ignorance and for being a Prius v interloper, but I am also a former GII owner. I never had any problems with the coolant themos and wonder why there seems to be such antipathy towards it. I have wondered why my v does not have this, as I thought it a nice feature that helped me have a warm engine asap each morning. Was it unreliable or just a pita when doing coolant changes without going to a dealer?

 

I must admit the thermos tank is something that baffles me. "luckily we did not get them on the UK Prius".
If the coolant in the thermos is hot or warm at first making the Prius ready, and it is pumped into the engine that means the cold coolant in the engine block must pushed back into the thermos. When you turn off the Prius the hot coolant in the engine is pumped into the thermos pushing the cold coolant in the thermos back into the engine "cooling the engine prematurely" If the car is then started after a short period the coolant is swapped again serving no useful purpose "in fact the engine would be warmer if the system had not changed the coolant. Further I cannot believe that after say 12 hours of being parked apart from in the very hottest of climates that there is any even warm coolant in the thermos.
If the car heats the coolant in the thermos while running that would be twice as much coolant to heat making the warm up longer. I can see there are situations where the warm up would be quicker, "say after a couple of hours after the car was turned off" but then you still have the downside of carrying round the extra weight of say 1 gallon of coolant, the thermos, brackets,and pipework, the pump, and control valve.
Am I missing something in the system as not having it on our Prius I am not able to examine it.

John (Britprius)

 

I don't think it worked that way exactly, although I'm not sure. It was my understanding that when emptied, the thermos was exactly that, empty. So all that is happening is that the warm coolent is pumped into and out of the engine when starting or stopping. I'm not really sure why they would need to, or want to for that matter, exchange coolant rather than just move it.

The benefit I saw was that the engine was up to temp much, much faster at the end of the work day (9 hours) and quite a bit faster in the morning (14 hours.) I saw no benefit at all that I could detect after a day off (38 hours) or longer. Again, if no one else noticed a benefit it may have been placebo, although I kind of doubt that. I could certainly buy that it was a mechanical complication that was no longer needed to meet a mandate, especially if it was a feature that no one valued.

 

I am not saying your wrong as I have no way of checking one way or the other, but the US coolant capacity is near double that of the UK system. Further emptying the engine of coolant could give rise to many problems with air locks and problems with hot spots "cylinder head" if the coolant was removed say on a hot day after a steep clime.

John (Britprius

 

1. The coolant heat recovery system canister is kept full of coolant at all times. While the car is in operation the engine ECU will open the engine coolant valve as necessary to route hot coolant either to the heater core or to the canister or both. When the car is made IG-OFF the CHRS pump will run, presumably to give the canister a final shot of heated fluid. When the car is first made READY the pump will run to circulate the heated fluid from the canister to the engine while the cool fluid moves from the engine into the canister.

2. The canister holds ~3 quarts and the capacity of the entire system is ~9 quarts so having 1/3 of the fluid relatively hot does provide some advantage to warming up the engine, although I personally think the complexity of the system outweighs any benefit.

3. US owners get the faster warmup benefit and pay for that benefit with increased engine coolant system complexity, potential failure of the coolant valve (which has been reported fairly often) and a noisy CHRS pump (which continues to function, but is just noisy.) The engine coolant system is not easy to purge air out of because of the CHRS system.

4. California 2G Prius owners and other owners living in states that follow CA emissions standards are the winners because the CHRS system is part of the advanced technology equipment that qualified the 2G Prius for AT-PZEV rating and as a result, the longer 10 year/150K mile hybrid system warranty.

 

Patrick thanks for the summary of the thermos system. I take it from your avatar that you live in a hot climate, and this must help. I wonder how how much heat is left in the thermos say in a Canadian winter after 9 hours outside in -20 and lower. I think the gen3 exhaust heat recovery a much better system, but obviously this is later thinking by Toyota.

John (Britprius)

 

Thanks for the info. I guess I was just lucky that on my Gen 2, I never had an issue with it for >$160k miles.