It was time to do my first coolant change. I read a lot of information here,(Prius Chat) and realized that trapped air can be a real time waster to remedy. The use of an air-lift tool is the solution to a carefree job. I've never needed such tool for previous vehicles, so I was without. What to do? I was thinking about this for a couple of days, before the light bulb moment arrived. Fill the coolant from the bottom up! The air should stay on top of the new fluid, and exit out the opened radiator cap. Time to try... If successful, I would share this method... (1) Drain all fluid out of the thermos bottle petcock, making sure to have the passenger side jacked up some, as this will allow more fluid to drain. Be patient, as it takes a while for all six quarts to empty. Now leave the petcock open. (2) Now you will need a S hook, or something to hold a jug to the hood latch. A long piece of plastic tubing is needed. ( 7' long x 5/16"(8mm) inside diameter) Test fit the tubing to the petcock before proceeding. Warming the tubing with heat will soften the plastic, if needed to expand and fit properly. (3) A hole needs to be made in the bottom of the jug. I used a tapered shank to make the proper diameter hole. Go a little at a time with your tool, test fitting the plastic tubing. You want a nice tight press fit. (4) Hang the jug from the hood latch. A funnel will allow the new coolant to pour into this container. Block the end of the tubing with your thumb, and fill the jug, or hold the end higher than the funnel, then seal the end with your thumb. Now bleed all air out of the tubing before attaching to the petcock. (5) The new coolant will fill much faster than it drained, due to the height of the jug. Do not let this jug run dry, as you will have to re-bleed the plastic tubing, to remove the air that is now in it. (6) After six quarts have been added, you will see fluid cresting the radiator cap. Close the thermos petcock. Remove the jug and plastic tubing. Keep the passenger side jacked up slightly, from step #1. (7) Run the thermos pump with a test meter, or paper clip, and listen. The difference in sound between air/no air in the system is huge. I did four 5 second runs. There was a little air. (8) Shove a funnel, or something that fits tight in the radiator cap location. Squeeze the large diameter radiator hose under the radiator cap many times, and see if any air bubbles come out. When satisfied, start the engine, place car in neutral, and let the engine run for about ten minutes. Make sure to set the parking brake, along with wheel chocks. The fluid level in the funnel will rise as the fluid warms and expands. Shut off the car, and let things cool. Now remove the funnel, and attach the radiator cap. You are finished... Note: Two days of driving and all is normal. I monitored coolant temps with Torque Pro, just to be be safe.
But ya had to rig all that up . You can drop almost all in quickly . It's the last two quarts at most are the issue . Pour slooowly and have other things to do . Walk by the offending car every five min top off . Until finally it doesn't move in 5 minutes then you're full cap off top of jug and go heat on hi . Then turn heat down or off . Probably not revisiting this for a very long time afterwards unless s leak doh.
Never tried it but did propose it: Refill ICE coolant loop through drain valve under thermos? | PriusChat Sounds like it worked well. Thanks for being first penguin off the ice and into the water. One comment though, I wouldn't hang anything heavy on the hood like that. The aluminum hood is pretty flimsy and it is just held up by a not particularly stout support - on only one side. It might warp, or it could fall down. Safer I think to hang the coolant from a tree branch, under a ladder, from an engine hoist hook, or basically anything that is handy and sturdy.
Three more minor points: 1. When the fill starts it is OK if there is a continuous air bubble from the valve back up into the tube, as long as there is a solid column of coolant above that. When the valve opens that air will be pushed into ... more air, so it is harmless. 2. It would probably be a good idea to fill slowly until the thermos is full, or at least mostly so. If the fluid enters so fast that it makes a fountain that will mix air also in the thermos into the coolant. It might be possible to tell if this is happening by listening to the side of the thermos as the coolant goes in. 3. Good idea to run the heat on full for a while when filling this (or any) cooling system. Heater cores are a notorious location for air to get trapped, and in the worst case it will prevent coolant from moving through the core at all.
Tried this today using a slightly different method. Instead of poking the tube through the bottom of the bottle the tube was prefilled with coolant and then dunked into a full 1 gallon bottle of coolant. Then the coolant siphoned out when the bottle was raised to about fender height or a little more. About a foot lower, I would guess, than the OP's method. A small funnel was jammed in next to the tube which made it easy to refill and also clamped the tube in place. 6 qts came out but during the fill. However, coolant appeared in the funnel at the radiator mouth at around 4 qts. The silly drain valve under the tank decided that it wanted to drip through its threads, during the fill, much more so than the during the drain. Closed the valve once that happened (no further dripping from the drain valve). Jumped the relay pins for 5 seconds at a time resulted in a ton of bubbles over the next minute or so and a lot of fluid dropping down from the funnel into the radiator. After 15 minutes of that about 2 qts more had been put into the system and no more bubbles. Then put the car in inspection mode and turned the cabin fan and heat up. Only a bubble or two came out in the funnel. After a while lowered the passenger side (it had been raised previously) and kept it running like that. The radiator hose near the radiator bleed valve got hot but the lower one was only warm, even after 15 minutes. The radiator fans never started. Ambient temperature was mild (cloud cover most of the day). I could squeeze the lower radiator hose, maybe an inch from the drive belt for the water pump, and it was hot in that area, but not burn your skin hot. (I didn't touch the motor itself, it probably was burn your skin hot.) Put the remainder of the coolant in the funnel into the overflow tank (just a hair above the center point I marked there years ago) and the radiator cap back on. There were a few small spills along the way, but it looks like at least 6 qts went back in, in the end. I didn't mess with the radiator bleed valve at all. Squeezing the top radiator hose while the relay step was going on pushed a few bubbles out and then I guess it was full. Squeezing the lower hose didn't make any bubbles at that point, probably already full of coolant. Odd that the OP had no air in the tank and 6 qts went in and this car had a ton of air and only 4 qts (ish) would go in during the gravity feed. My car had not been driven for four days (12V battery was changed, there were complications). It had been started and moved a few feet up and down the driveway, but that was it. Maybe the 3 way valve was in a different position? I am a little concerned that the radiator fans didn't come on after 15 minutes. There was a procedure somewhere for monitoring multiple temperatures in Techstream and plotting them to see if a "normal" warm up occurred. Anybody got a link to how to do that? Thanks.
Found it. It wasn't on PriusChat but here starting on page 5: https://www.automotivetechinfo.com/wp-content/uploads/2020/09/Mastering-the-Toyota-Gen-2-Prius-Engine-Cooling-System.pdf
if you have an air compressor you can buy a vacuum type coolant fill kit from amazon for $30 and be done with it really quick. It can be used in other cars too. It does 2 major things, check if you have a leak (it will not hold vacuum) and bleed trapped air.
I have the tools for that, and did that on a Prius once, but didn't find it had any strong advantage over just filling the way the manual says. It's the kind of procedure where all of the details you have to get right are in the setup. Make sure the source of coolant is above, not below, the coolant loop, and you've pre-filled your filling apparatus with no trapped air and all your connections are leak-free, and hook up your compressor to the vacuum venturi and open the right valves and let 'er rip. If you got all the prep details right, you just watch the magic happen and you get a good fill. If you get a partly-successful fill, you can't use the vacuum-fill kit to salvage it (the big hoses collapse and you end up spewing coolant out the venturi). So you either fully drain and try again, or just finish filling the same way the manual said to in the first place.
This is the method I used for this bottom up refill. For whatever reason it left a lot of air in the heat storage tank but not elsewhere. Supplies: 3x1 Gallon water bottles with screw tops, empty and dry. (In this instance all 3 were identical distilled water bottles and had not had anything else in them.) 2x1 Gallon Toyota OEM SLLC jugs. (Here jug 2 had been opened previously and a small amount used, while jug 1 was still sealed. Both were bought from the parts department at a Toyota dealership.) 8 ft of 5/16" clear vinyl tubing. (In retrospect it would be helpful to straighten it out before use. Here it was used straight from the store and had a strong tendency to coil back up.) Something to lift a corner of the car. (The jack from the trunk is adequate.) Tight fitting funnel for radiator. (Here Harbor Freight 58423 "No-Spill Radiator Funnel Kit" ) Small funnel. (Fits into top of water bottle along with vinyl tubing.) Tiny funnel or syringe. (For prefilling the tube.) Screwdrivers, socket set. (For removing radiator tray and front of fender liner.) Piece of wire or multimeter with leads. (For jumping the heat storage tank relay socket to run the pump.) Small drain pan. (Coolant drain valve drips when open and/or accidents happen.) Something to hold one water bottle vertical on the ground and also at a height above the high point of the radiator. (In this case I used my son. If working alone the water bottle would have to be held firmly by something or it could fall over from the tubing pulling on it.) Method: Vinyl tubing is not rated for the 180F fluid that may be normally in the heat storage tank. Here the car had been parked for several days for unrelated work, so the coolant was not hot. If the coolant is hot let the car cool off for a while (dropping the temperature outside the tank), then start the car, wait for the tank pump to finish, then shut it off and wait another while (for the ex-tank fluid to also cool off). Or, just drain it all into a big enough drain pan and don't use the tubing for the initial drain step. Park car (flat would be ideal, here driveway has a slight slope and the car pointed uphill), transmission in P, car off, rear wheels chocked. Remove tray over radiator. Jack up driver's front wheel at jack point until just off the ground. Remove 2 screws and 2 push fasteners on front of fender liner and let it hang down. Unplug wiring to pump for heat storage tank, located on the side of the tank facing the wheel. Push one end of the 5/16" vinyl tubing onto the drain nipple, put the other end into one of the empty water bottles and push the small funnel in to hold the tubing in place. The tubing wiggled onto the nipple pretty easily, it might not on a cold day, in which case warm it up a little first. Lower the driver's side of the car, jack up the passenger side until the radiator cap is significantly raised above the other end of the radiator. Stand up an empty water bottle as far downhill (if there is slope) as possible. Place the drain pan under the valve to catch any drips. Open the drain valve. The coolant will be sucked out of the overflow tank. Once that is empty remove the radiator cap and place it somewhere it won't get dirty. Keep an eye on the water bottle and be prepared to close the valve before it overflows. (Here it wasn't far enough down the driveway and stopped filling before reaching the top. Closed the valve, moved the tube to the 2nd water bottle, opened the valve, collected enough to top off the first bottle. Closed the valve, top off the first bottle from the second, open the valve, complete draining into the 2nd bottle. It had to be tilted at about a 45 degree angle or the water level in the bottle was higher than in the car. When the fluid stops coming out pour the drips from the valve into the 2nd water bottle. This part is optional. I wanted to measure how much liquid went in and out. Having a nice 50 pound digital scale on hand, weight was used. Empty water bottle 66g, 1st water bottle 4170g, 2nd water bottle 2194g. total (fluid only) (4170g + 2194g -132g) = 6232g First SLLC jug 4212 g, second SLLC jug 4116g, total 8328g (including fluid and jugs). Place a funnel tightly into the radiator neck. Fill the 3rd (empty) water bottle with a little less than 1 gallon of SLLC from the 2nd jug (here already open) and set it on the ground. (Allow some unused space so that it doesn't overflow when the tube is introduced.) Take the outer 4 ft. or so of the tubing, hold it up in a U shape, and drip SLLC into it until the U is full. Tap it to get any air bubbles out. Put a finger over the end of the tube and then rapidly plunge it into the water bottle with the fresh SLLC, all the way to the bottom. Jam the small funnel in next to it and then lift the water bottle until it is at least as high as the fender. It will immediately begin siphoning into the car. The air ahead of the liquid won't cause bubbles, it is just air going into a space already full of air at that point. Keep an eye on the funnel at the radiator neck and on the water bottle. When the water bottle SLLC level drops to around 2 quarts fill it up again from one of the SLLC jugs. (Because it is important not to suck air into the tube! One advantage of the water bottles for this is that they are transparent, whereas the SLLC jugs are not, making it hard to judge the amount of remaining fluid in one.) Here the funnel at the radiator neck had SLLC in it after only about 4 quarts had been introduced. (Differs from the OP's experience.) Whenever this happens, close the drain valve. Pour the leftover new SLLC from the water bottle into the Toyota SLLC jug which still has fluid in it. Pour the drips from the valve into one of the water bottles with the old fluid. Here it wasn't a lot of fluid, maybe 50 ml? Remove tubing (Here it was difficult, it held on tenaciously and had to be worked off slowly for fear of cracking the plastic on the valve). Thoroughly clean drain nipple, around drain valve, and fender liner, so later if dried coolant is observed it will be clear it is new and not something left over from this procedure. Reattach electrical plug for drain pump. Burp tank as described thoroughly elsewhere. In short, remove the appropriate relay and jump the designated two pins with a wire or multimeter leads, only running the pump for short intervals. Here initially 5 seconds of the pump running was followed by a minute of bubbles and significant amount of fluid dropping into the radiator. Top off funnel as needed. After about 15 or 20 minutes no bubbles appeared even after 20 seconds of the pump running. Roughly 2 quarts were added this way. Put car in inspection mode. Full cabin fan, temperature to MaxHot. Let it sit like that for 15 minutes. Only a few small bubbles were observed at the beginning and heat into the cabin was, well, hot. No gurgling sounds (when the cabin fan was turned down to low so that they might be heard). Give each of the big radiator hoses a few squeezes. (A little air out of the one near the radiator bleed valve, nothing from the other.) Lowered the car back to the ground near the end. The radiator hose near the bleed valve was hot at this point, the other radiator hose was not. (Ambient temperature was around 65F by this time.) Transfer the remaining SLLC fluid from the funnel into the overflow tank. If needed add enough fluid to reach the midpoint. Here the transferred fluid reached just a little over the midpoint dot previously marked on that tank. Put the radiator cap back on. Reattach fender liner. Unchock rear wheels. Reweigh SLLC jugs. First jug 1994g, Second jug 138g (now empty). Total liquid (8328g - 138g - 1994g) = So 6196g fluid into the car vs. 6232g fluid out. Drive car a little and park to sit overnight. In morning add SLLC from second jug to raise level to midpoint dot. Drive car normally, park to sit overnight. In morning check level (here, no change). Reinstall tray. Reweigh SLLC jugs. First jug 1918g, second jug 138g (empty). Total liquid (8328g - 138g - 1918g) = 6272g fluid into the car vs. 6232g out. Consistent with the small volume lost to valve drip and no air bubbles left in system. Done Ever wonder what the density of SLLC is? For yucks that was calculated too. A full SLLC jug was 4212g - 138g empty = 4074g of fluid. 1 Gallon = 3.78541 liters = 3785.41cm3. So measured SLLC density is 4074g/3785.41cm3 = 1.0762 g/cm3. This is 100% fluid from the previously unopened first jug. That is, however, not the density this MSDS claims, it says 1.115g/cm3. https://www.msdsdigital.com/system/files/Toyota_super_long_life_coolant.pdf That MSDS is from 2013 though, perhaps they reformulated since then? Here is another one MSDS from 2015: https://www.oil-club.ru/forum/applications/core/interface/file/attachment.php?id=119952 which gives a specific gravity of 1.08. Since this is relative to water (1.0g/cm3), it is consistent with the density calculated above.
