Coolant/Radiator Flush Question

[1985usa]

Hi fellow ToyotaNationites!

I'm new to this forum. I just purchased an 05 Corolla S with 95k. Lord only knows what maintenance has been done so I've decided to change all the fluids and replace a noisy blower motor. To cut to the chase, I've run into an issue with flushing the radiator and coolant out of the block.

I drained approx 3 quarts (I think), but I didn't measure it because I drained the coolant and then flushed water through into the same container. I only realized the problem after I could only put about 3 quarts of 50/50 antifreeze in. Below is the exact process that I followed.

1. Jacked up car and removed radiator cap
2. Drained radiator using radiator stopcock
3. Then emptied the block using the drain and 10mm bolt at the back of the engine block
4. Then replaced the radiator drain stopcock
5. Inserted hose into radiator through rad. cap area and filled radiator
6. Started car and turned heater on high.
7. Began flushing water through radiator and engine until fluid draining out of the engine coolant drain on back of block became clear.
8. Turned off water and allowed both radiator and block to fully drain.
9. Replaced engine drain bolt on back of block as well as radiator drain plug.
10. Filled radiator (approx 3 quarts only with 50/50 antifreeze)
11. Started car and allowed to run with heater on high again

Here's the problem...no more antifreeze would fit into the radiator after running the car. What should I do? Any ideas on what went wrong?

Thanks for the help.

[John Anthony]

Hey 1985USA, I have a 2004 Corolla LE. I replaced my radiator fluid about a month ago using pretty much the same procedure as you (except that I did not use tap water through a hose--I used several gallons of distilled water). The Corollas were initially filled at the factory with 6.9 quarts of radiator coolant (not quite 1 3/4 gallons). I too noticed that I could not fill it with 6.9 quarts even after draining from both the radiator draincock and the engine drain bolt in the back of the engine. I was able to fill in about 3 1/2 quarts. The conclusion to which I came was that draining from both the radiator draincock and the engine block drain does NOT drain all the coolant. Therefore, your pre-diluted 50/50 fill will leave you wil LESS than a 50/50 ratio because the water you used to flush the system is still partially in the system. I used straight non-diluted Toyota coolant mixed with distilled water. I figured out based on a full system of 6.9 quarts that I should use 3.45 quarts of straight coolant and the rest with distilled water. This got me pretty darn close to a true 50/50 ratio. Technically you have some tap water in your system and it could leave mineral deposits. My suggestion is to not use a hose, but to use distilled water until it runs clear, then use straight coolant and distilled water to achieve the correct 50/50 ratio. It's a pain in the rear, but I feel good knowing I did it correctly. Also, keep an eye on your overflow container over the next few days. It only took me 2 days of slightly topping it off to get it to the full mark after driving it a long time (it wasn't that far off anyway). If yours is full after driving several times, then the system should be full.

[Woodyg]

I started to do this yesterday on my 1zz and I could not find the engine drain. Do you both have the 1zz? I wonder where the rest of the coolant is. Some is probably in the heater core. I think I will try and figure it out before I start. The Stealership near me only carries the 50/50. I think I need the concetrated one. Thoughts? Has any one seen Mikered?

[Woodyg]

Originally Posted by 1985usa

Hi fellow ToyotaNationites!

I'm new to this forum. I just purchased an 05 Corolla S with 95k. Lord only knows what maintenance has been done so I've decided to change all the fluids and replace a noisy blower motor. To cut to the chase, I've run into an issue with flushing the radiator and coolant out of the block.

I drained approx 3 quarts (I think), but I didn't measure it because I drained the coolant and then flushed water through into the same container. I only realized the problem after I could only put about 3 quarts of 50/50 antifreeze in. Below is the exact process that I followed.

1. Jacked up car and removed radiator cap
2. Drained radiator using radiator stopcock
3. Then emptied the block using the drain and 10mm bolt at the back of the engine block
4. Then replaced the radiator drain stopcock
5. Inserted hose into radiator through rad. cap area and filled radiator
6. Started car and turned heater on high.
7. Began flushing water through radiator and engine until fluid draining out of the engine coolant drain on back of block became clear.
8. Turned off water and allowed both radiator and block to fully drain.
9. Replaced engine drain bolt on back of block as well as radiator drain plug.
10. Filled radiator (approx 3 quarts only with 50/50 antifreeze)
11. Started car and allowed to run with heater on high again

Here's the problem...no more antifreeze would fit into the radiator after running the car. What should I do? Any ideas on what went wrong?

Thanks for the help.

I id a little research on this topic and the consensus seems to be that around 2.5 quarts stays in the heater core and other plumbing. so I came to the conclusion that I will use the above method except I will not start the car. just run water though the system until it comes out clear at the drain plug. I then will drain the radiator and refill with the 50/50 coolant. if my theory is correct. I should not change the coolant ratio much at all as long as I don't start the car.....oh and I found the drain plug my reaching my hand down between the brake reservoir and the exhaust manifold at the back drivers side of the engine. I think I can get a ratchet in there from the top......thoughts

[John Anthony]

I have the 1zz engine. The other engine is the 2zz (I think) and that is only on the Corolla XRS from what I understand. Yes, I see that if you drain radiator fluid without starting the car that it makes it easier to keep the 50/50ratio, however you will be cycling through used fluid when you drive the car eventually using the heater and it will contaminate the new fluid you put in. Kind of like draining tranny fluid and refilling but not actually flushing all the fluid out. Do it often enough and I guess the "contamination" will be mostly weeded out. I still prefer to flush out all the radiator fluid.

Also, I found it easier to access the engine block drain by jacking up the car and crawling under the car and reaching up to access it. It was much easier to see it and reach it that way, but maybe you have long arms and can access it from the top, lol.

[Woodyg]

Originally Posted by John Anthony

I have the 1zz engine. The other engine is the 2zz (I think) and that is only on the Corolla XRS from what I understand. Yes, I see that if you drain radiator fluid without starting the car that it makes it easier to keep the 50/50ratio, however you will be cycling through used fluid when you drive the car eventually using the heater and it will contaminate the new fluid you put in. Kind of like draining tranny fluid and refilling but not actually flushing all the fluid out. Do it often enough and I guess the "contamination" will be mostly weeded out. I still prefer to flush out all the radiator fluid.

Also, I found it easier to access the engine block drain by jacking up the car and crawling under the car and reaching up to access it. It was much easier to see it and reach it that way, but maybe you have long arms and can access it from the top, lol.

I agree that it would be best to flush out all the coolant, however no one has been able to tell me how to do that. I guess I could pull the alternator remove the t-stat, reinstalled the alternator, buy gallons of distilled water and run the water though the car until it is all clear. then any water that would be left in there would be distilled. I then would get the concentrated coolant and mix in the appropriate amount after i removed the alternator and reinstalled the t-stat and put the alternator back in.........if there is another way to do that please let me know!

[John Anthony]

Removing the thermostat does help you do it much more quickly, but to me it isn't worth all the labor. If you are patient and let the engine get completely warmed up, the thermostat will open up anyways. Then you turn on the heater and let everything cycle through. You repeat this a couple of times and you will be able to get out all of the old radiator fluid without having to remove the thermostat. Professional mechanics like to remove the thermostat because they are pressed for time and doing it that way is faster than waiting for the engine to get hot and repeating the cycle a couple of times. If removing the alternator and thermostat is easy for you, then you can do it that way. I did it without doing that (but it took longer, of course). I bought several gallons of distilled water and repeated this procedure until it was just water in the system. Then I used the concentrated coolant and figured out how much to use (3.45 quarts) to obtain a 50/50 ratio in the system. So, you have a choice to make. I suppose either way would work.

[Woodyg]

I just did the simple procedure that midered30 had.....I used the petcock it was easier for me. a ran a little garden hose water though the rad just to rinse it out. I was able to undo the petcock from the top with a rathect and 10mm socket. I undid it some and did not seem to be getting much coolant just a trickle. I had already drained the radiator. I bolted it back in before I took it out so far that it came out..in the end I removed about 3.5 quarts of pink coolant and put about 3.5 quarts of new pink coolant. I will do the same thing again before the winter..... for a diyer this is an easy job and maybe it is not perfect but it will not hurt and will give the coolant system some new lubricants...