Changing engine coolant

Just wanted to thank you guys for this info and add a bit that I think helped simplify as well.

My procedure was:
-Leave the car flat.
-Don't open the radiator cap or overflow cap.

-Remove three screws and one pop off plastic retainer(this was the biggest issue I had, it would not separate itself properly) from the front left fender liner/cover which allowed access to the Thermos bottle.

-Unplugged CHS pump connector.

-Attached 3/8" hose(I believe) to the nipple on the bottom of the thermos bottle. I think 1/2" might be a better fit, it was REALLY tight. Though that might be good given the likelihood that hot coolant will come out and possibly loosen the hose and have it come loose.

-Loosen the yellow valve on the bottom of the thermos and let the coolant flow into container.(Looks like you could remove that entire valve and drain it quicker, but messier) That took maybe 10-15 minutes. Can't say for sure, but I'd guess about 6 quarts came out. I then removed 4 retainer clips for the cover that blocks the radiator cap, angled it a bit and opened the radiator/overflow caps and nothing more came out.

-Closed the thermos valve, removed the hose.

Here's the part where I hadn't noticed anyone mentioning:
-I used a funnel which attaches to the radiator cap. I noticed my mechanic use one and thought that was a great idea and found one on Ebay I think for like $25 when I was having headgasket issues on my 03'. Essentially it comes with fittings so that it replaces the radiator cap and seals there and then you have a funnel which holds like maybe 3 quarts. That way you don't have to keep re-pouring, you can easily see when bubbles come out and it raises the level of that spot like 6 inches, plus you get the added pressure of having all that coolant up there.

Anyway, with that attached and full of coolant it immediately put about a quart into the system and then stopped. But then it started letting bubbles out, and continued doing that for maybe 10 minutes, with one pause long enough where I went to get the multimeter to run the CHS pump, but by the time I returned a couple minutes later, it was bubbling again. Waited a bit more for that and it finally got to where I could count 60 seconds with no bubbles coming out and I just touched the CHS pump for a second, could hear movement and let the bubbles work their way out. Did that a few times, then worked my way up to letting the pump run for longer periods. But really, it didn't seem to matter. A couple seconds and the air was coming out, then wait till it was done and run the pump for a few seconds. But I did run it for 30 seconds towards the end.

So by the time that was done, it was around 6 quarts back in the system. I started the car and turned the heat to max and a few minor bubbles came out, but no real change in the coolant height.

I did let it start/stop itself a few times and then held the accelerator to the floor for a minute or two, but not much change.

It's cooling of now, but I'm hoping using that funnel made it easier to get the air out without standing around waiting to dump a bit more coolant in. There was a good bit of waiting around, but it wasn't like I needed to wait and then dump in a bit more coolant since I had 3 quarts in the funnel.

-I did button the bottom cover/fender liner back in, but I'm waiting for it to cool before I remove the funnel and button that back up.


But again, thanks for the info, or I imagine this would have been a lot more difficult!

Thanks!
Levi

 

Hi Levi,

I also have struggled with that plastic fastener. I'm wondering whether anyone has come up with a simple process to remove that?

Glad to hear that the job went smoothly, and thanks to you for the funnel idea which sounds great! If you have a link to that funnel, please share it.

I really appreciate the many posters who contributed their ideas to this string. Our collective efforts will make DIY 2G engine coolant change a simple and painless process!

 

I am guessing this means turn the CHS pump on. How ?

 

Refer to Posts #56 & 57 in this thread for pics and vid.

 

Umm, here's one:
Spill Free Radiator Funnel Kit

 

Thanks, I ordered from Amazon.com today for $23.56 (free shipping).

 

I did the same last night. Should have it Wednesday.

 

Looks (or rather sounds) like it wasn't quite as simple as I had hoped. I still haven't taken it out for a drive yet, but moving it in the driveway longer enough for the engine to start I heard coolant moving. I'll take a trip tomorrow and check again.

Is there concensus that the air doesn't work itself out through the overflow, but does in fact need to come out the radiator cap? Would be nice if that dang trim panel wasn't in the way of even checking that...

Funnel is definitely handy though.

Levi

 

If you hear air in the coolant system (for example in the heater core) then I think you should work on getting that out before you drive the car on the road. Try setting the car to inspection mode, then rev up the engine repeatedly over 20 minutes (or until you no longer hear air) while the heater temp is set to MAX HEAT and the fan is blowing at a high speed. Hopefully you'll see the coolant level drop in the radiator neck so that you can fill it up. After the engine cools down, more air may come out as well.

 

Bought a new inverter at the dealers today and installed and refilled coolant resevoir and radiator. Everything went smoothly but I never was able to loosen the bleed valve, I was afraid of breaking it with too much force. It should open in a CCW direction I assume??? I ran engine for probably less than a minute. Eventually the inverter stopped lowering and stabilized at full level. I did leave the car in readyfor about 15 minutes hoping toget rid of the air in the system. Have to put evertthing back together tomorrow, mostly the PIA stuff, like the floor under the engine and 10 million screws. The new pump seems to work fine, lots of bubbles. Not having a scan guage I'm not sure about overheating. I guess I'll just check often. For anybody contemplating this work, it's a bi_ch, tight spaces and frozen hoses. Finding all drains is also FUN. I never did find a drain on the radiator overflow tank. Still have to try above procedure ( Post 69 )

 

1. Regarding the inverter coolant loop bleed valve, you should use a box wrench on the hex below the nipple, and an open-end wrench on the hex-shaped body. Then you can exert sufficient force CCW to loosen the nipple, without damaging anything.

2. If you ran the engine for 1 minute that is not enough time to get air out of the engine loop. Need to put the car in inspection mode so that the engine will continuously run.

3. If you hear air bubbles while the inverter pump is running, that is a good clue that the system is not purged of air so you need to work at it until the bubbles go away - or risk damaging the inverter.

4. The radiator overflow tank does not have a drain. The radiator itself has a drain near the bottom. However if you drain engine coolant via the coolant heat recovery canister drain, then you really don't need to drain fluid at the radiator.

5. The top of the radiator has an air vent that can be accessed via a hole on the stamped steel frame over the radiator, on the driver's side. Use an Allen wrench to open that vent, when you are working on getting air out of the engine coolant system.

 

Thankyou Pat for your very precise instructions, tomorrows work.

 

I never did follow up on that. Whatever gurgle while moving the car into the garage I heard was apparently the last of any air. I couldn't add anything after it sat again, and then I took it out for a drive and didn't hear any gurgling and again there wasn't any room for more fluid.

I really think the funnel that attaches to the radiator cap makes it WAY easier to get the air out. Just fill up the funnel periodically and when the air stops making noise, run the thermos pump for a couple seconds and repeat.

Levi

 

I bought this funnel after you had recommended it, but have not yet had reason to use it.

 

While I was filling the radiator, for each quantity of coolant I got an equal amount air out. Any spillage was from the radiator burping. On the back firewall valve I attached a plastic hose to watch it and avoid spillage. It was a very interesting phenomenon. The fluid would surge out fairly rapidly and then stop, get a breath (equalise) and then repeat the surge. Altogether I got about a gallon out. Half from the main drain and half from the firewall valve. The venting back into the inverter resevoir worked perfect. This time the airbleed vent opened easily. I forgot about that double wrench method. The inspection mode also worked quite nicely, on/off periodically, so there was no fear of overheating. I believe the job is finished, but will still inspect from time to time. " Thanks Again Pat Wong " I spoke too soon, today I drained the thermos and even tho I had driven about 45min in suburbia the coolant was not even warm. Put in some new coolant, purged and ran engine in park, then I drained some more and coolant was mildly hot. Took it for a test drive and got red triangle whenever I speeded up to about 45. Red triangle would disappear when I let off the gas. I figured it must be telling me something. I stayed in my neighborhood so I easily limped back to my garage and found the radiator was low. Topped it up with coolant and just drove the car and it seems fine. Will check level again tomorrow. What was the reason for cool temperatures out of the thermos after a 45 min drive???? ( Before draining thermos ).

 

Something to Ponder! Topped up some more today ( not a lot ) but, even after a long drive, 40 mile trip, the water in the pipe, where the radiator cap is is not even warm. I should think it would be Hot, as is the case on a normal car! Could it be that my thermostat is not opening?

 

Hi Andy,

I am a bit confused by your post #75 above: "on/off periodically". If the car is in inspection mode, the engine will run continuously and you will see the red hybrid vehicle icon flashing in the upper left corner of the MFD. If the engine turns off then the car is not in inspection mode. I also don't know what the "back firewall valve" is.

I think that your car still has air in the engine coolant system. Although it is too late now, I would have advised that you work on only one coolant system at a time, and make sure it is right before proceeding to the other system.

I suggest that you put the engine in inspection mode, set the cabin air temp to MAX HEAT, turn the cabin fan speed to the fastest speed, and rev up the engine as much as you can (which will be ~2,500 RPM). Rev engine speed up and down for 20 minutes. While you are doing that, listen for air bubbling in the cabin heater core.

You should eventually hear the radiator fan running and feel hot coolant in the hose leading from the thermostat housing. If you don't, continue to rev up the engine again for another 10 minutes. (If, after running the engine continuously for 30 minutes, the thermostat doesn't open, then you may have a problem there.)

I do not suggest that you drain fluid from the CHRS canister as a way to assess the temp of the canister. Rather, when you next start the car and hear the pump running, at that time feel the outlet hose to determine the temp of the coolant within. However note that the canister has to have a chance to fill up with hot engine coolant, which requires that 1) no air is in the system and 2) the pump has to run after the engine is shut down.

 

Hello Pat, I will try to clarfy. I have a type 3, and have never seen a ready light, in using your procedure for inspection mode, I turned the ignition ON ( foot on brake ) then 2 presses on the go pedal in each position P-N-P and it went thru this periodic engine run and shut off mode for about 6-8 times, ....really! I knew that this was not what you were describing but ,what the hell. I have been looking for that engine bleed allen screw that you mentioned. The car ran fine today but having no hot temperature at all on the radiator cap or hot coolant in the well, bothers me. I also tried inspection mode in the auxilliary mode ( NO foot on brake ) the problem there is the dashboard is not lit up so I cannot verify gear positions. Anyway it didn't work. In regards to your 3rd para. I did get the engine hot enough to run the radiator fans and maxed out the heating system, this was in P/N. I thought I burned out the inverter as I only had two red bars and was not charging even tho I had the accelerator floored! then, I remembered, the HV only gets charged in Drive. The large rubber hose from the radiator to the engine was very hot after todays drive. I'll look for the hose coming out of the cannistor tomorrow. I saved and filtered the old coolant, there were many small brown particles and some larger black particles in it. I wonder with all those particles and the rusty color of the coolant if a flush on both coolant systems around 50 K miles would be more logical. Back fire wall drain is the engine coolant drain on the rear of the engine. This is one crazy car.:cheer2: PS On IM I neglected to press power button again, toward end of procedure, try again tomorrow.

 

Checked radiator cap this morning before heading for the Casino, cool. Fluid under cap: cool. Ran car about 50 miles, in one section I did 70MPH with full high heat (10 miles) Arrived at destination and checked cap and fluid again.....cool. All systems worked fine. Large black hose going into radiator ( I presume that is where the thermostat is) was hot. Does that portion ( ie; the radiator cap ) of the engine coolant system NEVER get hot? The passenger heating system worked fine. Oh, Tried IM and engine only ran a minute or so, is this what IM is about? Seems just like a normal start-up, NO Triangle! Battery status: HV= Greeen Acc = 12.7V TRIP Home: 50 miles again. Cap and coolant just tepid, found allen bleed screw, but nothing special happened, lost a bit of coolant. The only difference in the two trips is: 48F in the morning and 68F in the afternoon

 

Hi Andy,

Please refer to the following string regarding inspection mode:
http://priuschat.com/forums/gen-ii-prius-main-forum/71580-cant-get-inspection-mode.html

If the engine turns off on its own, you are definitely not in inspection mode.

If you can drive 100 miles round trip incl. proceeding at 70 mph for 20 miles and the engine does not overheat then I think you are OK. The Prius does not generate a tremendous amount of excess heat which is one reason why its mpg rating is so high.

You may want to practice invoking inspection mode. Other than that, I think you can declare victory on this project.