Radiator flush or not??

[Patrick Wong]

Originally Posted by V8Cobrakid

then don't add 50/50... buy pure. they sell it.

Yes, you can buy red Toyota Long Life Coolant from your friendly Toyota dealer. This coolant is not premixed and consequently costs less than SLLC. However the service spec for changes using the red LLC coolant is 30K miles compared to 50K miles (after the factory-fill coolant has been replaced) for the pink SLLC.

I'm assuming you would not use a cheap aftermarket coolant like Prestone, Peak, etc. in your Prius.

[smtrader]

Just picked up some SLL coolant at Norwalk Toyota for $15 a gallon (coupon). The service guy suggested 2 since I need 1.5 to fill the radiator.

So, the discussion about distilled water flushing got me worried about not getting "all" the water out when I drain it, thus leaving water behind and diluting the already diluted SLL coolant I bought. If I drain everything in sight, will there be that much left to make a difference??

Any suggestions about changing the thermostat?? Thanks!

[Patrick Wong]

Ed's suggestion was just to drain the radiator and leave the engine block and coolant heat recovery storage tank drains untouched. He further suggested flushing the system with distilled water. His reason for suggesting that was to reduce the chance of introducing air into the system. However, as we've discussed, the disadvantage of using distilled water for flushing is that you will end up diluting the final SLLC coolant added to the system.

If you open up all three drains: radiator, engine block, and coolant heat recovery storage (CHRS) tank - then you will have done a comprehensive job and should not have to worry about residual fluid in the system. Further, my recommendation is that flushing with water is unnecessary if the drained coolant does not have sediment within.

If you open up all three drains, then you will be faced with the issue of purging air out of the system, especially the CHRS canister and plumbing. Ed recommended the MityVac tools for this purpose. I haven't done this job yet, so I don't know how tough it is going to be. My idea is to provide 12VDC to the CHRS pump as a way to fill up the canister and purge air in that part of the system...

If you decide to proceed with this work, I suggest that you take some photos, especially of the CHRS system, so that other owners can see how easy or hard the job will be.

Yes, I suggest that you change the thermostat while you are at it, and inspect the radiator hoses. Don't forget to get a new O-ring for the thermostat housing.

Good luck...

[andyprius]

After replacing coolant, wouldn't a prolonged engine run-up with radiator cap off cause the trapped air bubbles to float to the top?

[Patrick Wong]

Hi Andy,

Not necessarily, since the Prius engine coolant system is more complex than most. You will need to run the heater at max temp for an extended period, to get air out of the heater core. It should be possible to hear air bubbling around in the heater core, so this will allow you to determine when the air is gone.

The coolant heat recovery pump only runs for a few seconds upon engine startup and shutdown, so it is unlikely that air will get purged out of that part of the system unless you take active measures.

[andyprius]

Originally Posted by Patrick Wong

Hi Andy,

Not necessarily, since the Prius engine coolant system is more complex than most. You will need to run the heater at max temp for an extended period, to get air out of the heater core. It should be possible to hear air bubbling around in the heater core, so this will allow you to determine when the air is gone.

The coolant heat recovery pump only runs for a few seconds upon engine startup and shutdown, so it is unlikely that air will get purged out of that part of the system unless you take active measures.

Always, reliable answers, Thanks Pat

[smtrader]

Thanks for your answers, Pat. How about some suggestions about changing the thermostat? Where is that thing anyway??

[Patrick Wong]

Originally Posted by smtrader

... How about some suggestions about changing the thermostat? Where is that thing anyway??

The thermostat is hiding behind the water inlet housing. One of the radiator hoses leads to the water inlet housing, and the engine oil dipstick is nearby.

The water inlet housing is attached to the engine block with two nuts and the tightening torque is 80 in.-lb. When installing the new thermostat, the jiggle valve should be at the top. Don't forget to install a new O-ring gasket.

[smtrader]

Patrick,

This ongoing thread radiator is VERY informative but also getting a bit scary for a novice like myself (I have only changed my own oil!). Since I live close to Orange County, and chance I can meet up with you for some hands-on guidance? (e.g. point out what is what??) Would much appreciate your time!

Let me know please...Brian 562-857-1829

[plantz]

Originally Posted by rumpledoll

Toyota switched to a long life antifreeze using a Hybrid Organic Acid Technology, and like all Japanese manufacterers they use no silicates and they do use phosphates. The Toyota Pink is good for 100,000 miles/10 years and 50,000 miles/5 years afer that.

Rumple

This is a little unclear to me.

I let my dealer "flush" the coolant at 30,000 miles. (It's a long story. In summary, I (stupidly) let them sell me a super service. On the plus side, when I complained to the service manager, he gave me $250 credit toward future service, which they have honored without complaint.)

Anyway, does your 100k then 50k statement mean that once it's changed, it should be done every 50k after that? I'm inclined not to do it again until at least 100k (70k after the first flush at 30k).

Bob