Radiator flush

[esse10]

Can anybody who is familiar with coolant flush and refill answer this question? How can you refill back the engine block back with coolant after you drain the complete block by opening the engine block drain cock??? When you put coolant back into the system the thermostat by the lower hose is closed and you fill up at the radiator cap? thermostats do not work normal with just heat it needs liquid heat temperature. has anybody done a complete drain and refill of their coolant system and what experience did you see? Seems like the block would be without coolant for a while until the thermostat opens but by then you could have done damage to your engine block. HMM?

Any past experience help , tips would be appreciated folks

thanks......

[CTScott]

Can anybody who is familiar with coolant flush and refill answer this question? How can you refill back the engine block back with coolant after you drain the complete block by opening the engine block drain cock??? When you put coolant back into the system the thermostat by the lower hose is closed and you fill up at the radiator cap? thermostats do not work normal with just heat it needs liquid heat temperature. has anybody done a complete drain and refill of their coolant system and what experience did you see? Seems like the block would be without coolant for a while until the thermostat opens but by then you could have done damage to your engine block. HMM?

Any past experience help , tips would be appreciated folks

thanks......

When you refill, leave the back drain open until water flows out of it and then close it and continue to fill via the radiator cap. The thermostat has a bypass hole that will let the water through and let it push the air up as the water fills the block. There will still be air pockets, so once it is full you start the engine and run it with the cap open. You will keep adding fluid as the bubbles make their way out, and once the thermostat opens quite a bit more air will come out.

[esse10]

Hey thanks, I didn't know that the thermostat has a bypass hole. I have not done the job yet but looked at a few thermostats online for this particular car and didn't see any bypass holes. I have heard of some thermostat having a hole and some don't. keeping the block drain cock open until i get coolant come out is agood Idea, i'll try that.

one more question ctscott since you seem to have lots of experience with these yaris cars, Is it a common failure for the Radiator to develop cracks on the upper section? on these cars I mean? Poor quality part from toyota or previous owner just put a used cheap radiator? The car is only 4 years old and I would think a radiator would last longer than that....hhmm?

[CTScott]

Hey thanks, I didn't know that the thermostat has a bypass hole. I have not done the job yet but looked at a few thermostats online for this particular car and didn't see any bypass holes. I have heard of some thermostat having a hole and some don't. keeping the block drain cock open until i get coolant come out is agood Idea, i'll try that.

one more question ctscott since you seem to have lots of experience with these yaris cars, Is it a common failure for the Radiator to develop cracks on the upper section? on these cars I mean? Poor quality part from toyota or previous owner just put a used cheap radiator? The car is only 4 years old and I would think a radiator would last longer than that....hhmm?

I don't think it is common for the upper radiator to crack. On my (now) 4 Yaris I have only had one issue with a leaky top.

my 09, which was purchased new has not had any issues. Crashy (the snowplowing Yaris), still has its original radiator, which survived complete front end devastation. Crashy2 (the red one) has a junk yard replacement, only because the overflow tank was damaged (but the original radiator was still fine even with its front end collision).

The only one with a leaky top was my latest acquisition of the one that I am parting out. It does have a leaky top end, but it also had the entire front frame section pushed 4" to the left and 3" up.

[esse10]

k, thanks YOU THE MAN ! :thumbsup:

[Mittelklasse]

Alternatively, this is how I did:

1. Engine off and cold, drain the expansion reservoir.
Then, flush it several times with tap water till the water becomes clear.
Refill the reservoir with tap water.

2. Unplug radiator inlet (top) hose. Place a bucket beneath to catch the toxic coolant.

3. Run the engine. When the thermostat opens and coolant flows out of the block,
top up the reservoir with tap water. Let it flush the block until the outlet water is clear.
(You guys with heater might need to turn it on too, for a complete flush)

4. Stop the engine. Drain the reservoir again. Fill it with your coolant of choice and (preferably)
distilled water, up beyond the FULL mark. Don't plug the radiator inlet hose in yet.

5. Run the engine again. The coolant will push the previous tap water out of the block.
Top up the reservoir when the coolant level falls below the middle point.
(To prevent air from entering the system)
Keep an eye out on the color of the outlet water, and be ready to plug the hose back in.

6. Let it circulate good. 'Massage' the hose to push out any residual air bubbles.
Top up the reservoir if necessary.

[esse10]

Alternatively, this is how I did:

1. Engine off and cold, drain the expansion reservoir.
Then, flush it several times with tap water till the water becomes clear.
Refill the reservoir with tap water.

2. Unplug radiator inlet (top) hose. Place a bucket beneath to catch the toxic coolant.

3. Run the engine. When the thermostat opens and coolant flows out of the block,
top up the reservoir with tap water. Let it flush the block until the outlet water is clear.
(You guys with heater might need to turn it on too, for a complete flush)

4. Stop the engine. Drain the reservoir again. Fill it with your coolant of choice and (preferably)
distilled water, up beyond the FULL mark. Don't plug the radiator inlet hose in yet.

5. Run the engine again. The coolant will push the previous tap water out of the block.
Top up the reservoir when the coolant level falls below the middle point.
(To prevent air from entering the system)
Keep an eye out on the color of the outlet water, and be ready to plug the hose back in.

6. Let it circulate good. 'Massage' the hose to push out any residual air bubbles.
Top up the reservoir if necessary.

So you had no concern with putting regular tap water in the coolant system? I thought that was a big NO NO cause you won't get it all out.
I don't think the reservoir is connected directly in the coolant loop, well not in my car it ain't.
on mine it is connected to the pressure cap on the upper flange and only opens under pressure or or suction from the coolant system I believe.
One more dumb question, So the coolant circulating loop is that the coolant go's into the engine block from the bottom when the thermostat opens and then comes out back into the radiator through the top hose? is that correct?

[Mittelklasse]

So you had no concern with putting regular tap water in the coolant system? I thought that was a big NO NO cause you won't get it all out.
I don't think the reservoir is connected directly in the coolant loop, well not in my car it ain't.
on mine it is connected to the pressure cap on the upper flange and only opens under pressure or or suction from the coolant system I believe.
One more dumb question, So the coolant circulating loop is that the coolant go's into the engine block from the bottom when the thermostat opens and then comes out back into the radiator through the top hose? is that correct?
It seems water quality varies greatly from place to place.
My rule of thumb if that it's good if it's safe enough to drink once in a while.

Also, it seems I've caused some confusions.
What I did mean was, there are 2 coolant reservoirs: one is the expansion tank, and another is in the radiator.
Sorry, English is not my mother tongue. :biggrin:

You're correct on that one. If the coolant level drops past the top hose, the lowermost hose will still be able to feed the water pump.

[jcboy]

So you had no concern with putting regular tap water in the coolant system? I thought that was a big NO NO cause you won't get it all out.


You are right on. You should only use distilled water and not any other. Mineral water and any other type (even those okay to drink) have minerals which can clog (eventually) the hoses, coolant lines in the engine, the radiator, and so on.

Ok, so here's how i refill the radiator. and it has worked for me for a little under 2 decades.After the car sits about 30mins after use:
1. Drain radiator using drain plug. Reinstall the plug.
2. Refill radiator with distilled water.
3. Run engine with 2 cycles of radiator fun turning on and off.
4. Do steps 1-3 twice more. This should clean the cooling lines.

5. (as Scott mentioned) Run engine with rad cap off and be prepared with distilled water to pour on the radiator mouth after water overflows with fan turning on (do it while water seeps down).
6. Do step 5 twice more. This should completely bleed the cooling system of any bubbles/air.

HTH

[esse10]

Thanks folks for y'll input. It's a done deal and the car is running OKIE-DOKIE.
I thought Toyota made quality parts? the Raidatior is made of hard plastic and aluminum. Well at least it was cheap online...LOL :biggrin: IF this happens again i'm spending the extra $ and putting a pure solid all aluminum radiator.

I learned a few things for next time; No reason to drain the engine block with the small drain cock in the back, very little comes out. Another option which I found helpful is that You can fill the engine block first by putting a 3/8 tubing hose directly into the block and with a small funnel pour some coolant in just to make 100% sure the block has coolant when you start it up again.