Engine Coolant Replacement Interval and General Information for DIY Discussion

12295 Views 31 Replies 12 Participants Last post by Tazio Nuvolari, 2 mo ago

Urmil

Discussion Starter · Jul 20, 2021

2

I've been reading a lot of different information about when one should change the engine coolant. After much research, below is what I've found. I'd love some constructive feedback from anyone who has experience with DIY engine coolant changes. This information may also be helpful to others when it's time for them to have their coolant replaced.

Interval: First change should be at 100,000 miles or 5 years (whichever comes first), after that, every 5 yrs. or 50,000 miles (whichever comes first)

Coolant: I'll be using Toyota OEM 50/50 Prediluted super long life antifreeze/coolant (pink cap)
OEM Toyota Coolant

Now for the questions I have....

1. Does anyone know how much coolant is needed for the Rav4H? The coolant is sold in 1 gallon jugs and I'd like to know how many I should have on hand before starting the process.I believe the car will take approx. 2 gallons.

2. I believe to drain the old coolant, we have to locate the radiator draincock which is typically found on the bottom of the radiator. I believe on the Rav4H it's actually connected to one of the hoses. Below is a picture of the draincock I believe needs to be opened to drain the old coolant. Can anyone confirm this?

3. Under the hood, there's two reservoirs nearby. As per the owner's manual (page 572-573), the one on the left is the engine coolant reservoir, and the one on the right is the power control unit coolant reservoir. Once I drain the coolant, do I need to add new coolant to both of these reservoirs or can I just add it to the engine coolant reservoir and it'll flow into the power control unit coolant reservoir as it fills?

4. Is there anything else I should know about engine coolant changes? I'm a newbie but I do know that you should never open the coolant cap on a hot or recently driven vehicle.

P.S. I've found "The car care nut" youtube challenge extremely helpful since the host is a master toyota mechanic. Below is a link to his video on coolant that I based this thread on.

Youtube: How to maintain your Toyota Part 2 Engine coolant and Transmission fluid

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Tazio Nuvolari

· #2 · Jul 20, 2021

IDK if hybrid radiator is identical to the ICE gas engine radiator, but on the gas engine there is a metal radiator cap on the radiator distinct from the plastic reservoir bottle. When refilling I would fill the radiator directly from this and top off the reservoir later. Also IDK what the bleeding procedure is to get air bubbles out of the Dynamic Force engine and what the procedure is to drain, flush and refill the heater core.

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NameofUser

· #3 · Jul 21, 2021 (Edited)

It behooves you to get the factory service manual, so the information is correct and you will have torque specs for the fasteners. Most importantly, you’ll know what you are doing and not rely on the Internet/YouTube which may have partially correct info.

This person figured out a way to convert the CHM file format on TIS (Toyota’s Technical Information System),to a PDF format. Time consuming, but worth it due to the info in the Factory Service Manual.

priuschat.com

Toyota TIS download tips

How to download repair manual from TIS The toyota information system contents toyota vehicle repair manual which used to be PDF links, it's now chm...

priuschat.com

All Toyota hybrids and PHEV have TWO INDEPENDENT cooling loops:
ICE (Internal Combustion Engine) and Inverter (power control unit).
BOTH loops are independent of each other and cooled by the radiator; the radiator is split into an upper and lower chamber. If you drain one loop (ie ICE) you need to refill and purge air for the ICE loop only.

1st ICE coolant drain and fill should be at 10yr/100k miles, then every 5yr/50k miles.
1st Inverter coolant drain and fill should be at 15yr/150k miles, then every 5yr/50k miles.
I would just change both loops at the same time: 10yr/100k miles.

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Melwig

· #4 · Jul 22, 2021

Coolant change on the dynamic force engine is not like an old school engine where it is simply out with the old and in with the new. The coolant flow in this engine is controlled by coolant valves and an electric variable speed coolant pump. This system requires a very specific bleed procedure to ensure all air is out of the system. You definitely want to get your hands on the procedure in the service manual before attempting it.

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Jack Daniels

· #5 · Jul 22, 2021

Melwig said:
This system requires a very specific bleed procedure

If you still want to DIY the coolant replacement, you can open the drain valve on the lower radiator when the motor is cold and let it start to trickle out. Then refill with new fluid at the top while the motor runs. Old and new will mix together and you may end up with about 50% new fluid after the job is done depending on how much fluid you want to buy.
If enough fluid is used, the result could be >80% new fluid.

JFox562

· #6 · Jul 22, 2021

Who else has heard of the aspirin in the thermostat to keep it partial open while filling an empty system with new fluid?

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Jack Daniels

· #7 · Jul 22, 2021

Never heard of that one.
Most 4 cyl. Motors I have changed more or less bleed themselves while driving, cornering and centrifugal force helps. No need for aspirin or other foreign additives.

NameofUser

· #8 · Jul 23, 2021

JFox562 said:
Who else has heard of the aspirin in the thermostat to keep it partial open while filling an empty system with new fluid?

Unbelievable.

Who or whatever told you that, STOP listening to their beyond STOOOOOOOOOOOOOOPID advice.

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RENE65

· #9 · Jul 23, 2021

With all the electrical in the cooling system ( water pump, thermostat, heater coolant valves etc ) are you sure you can do better than the dealer ??? HOLD MY BEER AND WATCH THIS LOL . What can go wrong ?

Urmil

Discussion Starter · #10 · Jul 23, 2021

RENE65 said:
With all the electrical in the cooling system ( water pump, thermostat, heater coolant valves etc ) are you sure you can do better than the dealer ??? HOLD MY BEER AND WATCH THIS LOL . What can go wrong ?

No, I do not. If it’s a complicated process I wouldn’t want to DIY and risk damaging something.

I still have a few years before needing to do this so I’ll see what information is available regarding this topic in the upcoming years. Worst case, I don’t mind paying the dealership to do this since the change interval is not frequent.

NameofUser

· #11 · Jul 23, 2021

RENE65 said:
With all the electrical in the cooling system ( water pump, thermostat, heater coolant valves etc ) are you sure you can do better than the dealer ??? HOLD MY BEER AND WATCH THIS LOL . What can go wrong ?

1) I can do better than the dealer! Many stories of overpaid dealer service techs f'n it up on the Gen2 Prius (20004-2009). Ehh. The Gen2 Prius cooling system is still the MOST complicated and a PITA to purge air due to the "thermos". A design that was eliminated on Gen3 Prius and all other Toyota hybrids in USA and CAN that followed.
2) The techs learn somewhere, as they weren't born w/ that knowledge. Sometimes at a trade school (not necessarily on a Toyota Hybrid). Many times they will learn doing it on your car the first time! Doesn't this fact make you feel good knowing you are paying a shite ton of $ for someone to learn by doing it on your car?
3) If OP gets the Factory Service Manual, he can see the step by step procedures listed and determine if he is comfortable to DIY.
4) W/O even seeing the service manual, I forsee the coolant refill process on a RAV4 hybrids w/ an elec water pump actually being a lil easier! How/Why? The elec water pump will likely be activated to force coolant movement, and w/ that, air bubbles. The heater control valves and heater pump can also be manually activated too. The manual activation will likely be accomplished w/ Techstream software (via min VCI cable, available from Amazon/fleaBay) or a service caliber OBD2 code reader.

Many postings about Techstream and miniVCI cables over at ToyotaNation. W/ Techstream, you will have the same dealer capacity to read ALL Codes and perform vehicle specific maintenance procedures that require activation via Techstrram or other service caliber OBD2 machines.

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JFox562

· #12 · Jul 23, 2021 (Edited by Moderator)

NameofUser said:
Unbelievable.

Who or whatever told you that, STOP listening to their beyond STOOOOOOOOOOOOOOPID advice.

Please explain why this is beyond stupid (yes it's spelled with a U not O's).

I thought it was a brilliant idea since I had a ton of problems purging the air from a 94 Chevy Cavalier. 1/4 of an uncoated aspirin holding the thermostat open just enough to allow for the upper radiator hose to be filled with the engine off. Once you start the car, the pill dissolves and isn't enough to cause any issue with the coolant.

Dr. Dyno

· #13 · Jul 23, 2021

Okay guys you're starting to give me a headache so I deleted the ramping up rants and closed the thread.
Take an aspirin and DON'T call me in the morning.

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Dr. Dyno

· #14 · Jul 24, 2021

For the benefit of others having the same questions as the OP I'm reopening this thread.

But we don't need some members jumping down the throat of another one who mentioned a rather unorthodox method to hold the thermostat partially open for venting (which would probably work). In the case of only replacing the coolant it isn't too practical since one would have to do some disassembly to get to the thermostat.

Back to the OP's initial post. In his case I'd advise paying the dealer to do the job ... five years down the road.
My '18 Accord Hybrid has the same dual cooling system. One reservoir for the ICE and a second for the electric motor drive .
I'm sure that's because the gas engine wants to warm to its optimal temperature for most efficient running and to produce cabin heat. I'm not completely sure what temperature the electric drive is happiest at but it must be lower. That explains the two independent systems.
Yeah, I could change the coolants myself 4-5 years from now but I may have the dealer do it ... but by then labor will likely be $300-400/hr!

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SeanBeanDiesInTheEnd

· #15 · Jul 26, 2021

Here's a few docs courtesy of another user on the coolant for hybrids.

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Urmil

Discussion Starter · #16 · Jul 26, 2021

SeanBeanDiesInTheEnd said:
Here's a few docs courtesy of another user on the coolant for hybrids.

@SeanBeanDiesInTheEnd : Thank you very much for sharing this information. It appears to outline the process step-by-step. Personally, after reading this material, I'm not comfortable doing the coolant change at this time (nor do I need to). Hopefully, as the hybrid vehicle ages, I'm sure someone will post a youtube video showing the process. That might give me the courage to attempt this when the time comes.

Tazio Nuvolari

· #17 · Jul 26, 2021 (Edited)

SeanBeanDiesInTheEnd said:
Here's a few docs courtesy of another user on the coolant for hybrids.

Thanks for the pdfs. The coolant replacement procedure in the first two appear to be for the gasoline engine coolant. The others relate to hybrid components. Assuming the ICE gas engine RAVs use the same procedure as the hybrid gas engine, for the gas engines this is really a simple and straightforward job. Nothing exotic that a DIY guy could not do. Simply drain radiator and engine and refill. Only unusual thing is the rigamarole about "engine coolant filling mode" which seems to simply involve revving the engine while in park -- though it does not explain how this would remove air bubbles unless they just get "burped" into the reservoir while you rev and hold at 3000 RPMs. These instructions though strangely don't say anything about the heater core on the gas models I assume because the hybrids use a different heating system? I think that in a couple years there will be a bunch of YouTube videos showing the procedure. The 5th gen RAVs are too new for anyone to have changed the coolant unless they use their car as a taxi.

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Jack Daniels

· #18 · Jul 27, 2021

Tazio Nuvolari said:
"engine coolant filling mode" ... seems to simply involve revving the engine while in park

I'm skeptical to to this though I guess this method is cheaper for a workshop as the mechanic can bill for other work while the car is unattended.
Some workshop manuals specify putting a tool/plank on the gas pedal and holding 2500 rpm for 30 min. I prefer to just take the car for a drive where gravity, centrifugal force and using all the heater modes does the job.

RENE65

· #19 · Jul 27, 2021

We have an electrical water pump , how does reving the engine help ????

Melwig

· #20 · Jul 27, 2021 (Edited)

This engine has computer controlled coolant valves that control the passage of coolant through various parts of the engine. The engine reving procedure instructs the computer to open all coolant control valves for the purpose of getting an effective purge of all air from the system. It is not the same as just driving it around for awhile.

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