Coolant flush question

[91merc]

Had to do multiple flushes to my rusty cooling system after I got an air bubble and had to add a bunch of water in an emergency. I was wondering the best way to make sure all of the air is burped out of the cooling system, I put 2 gallons of the total 3.5 gallon capacity back in so far

[Tiggie]

A ton of it stays in the heater core and block, even if nothing else comes out of the radiator.

I've never had a problem with these taking coolant. I can usually get 80%+ of what came out back in. I drive it around for a couple miles, let it sit overnight, and check it again the next day to add any additional. I do use thermostats with a hole in them to potentially prevent those air bubbles.

[91merc]

A ton of it stays in the heater core and block, even if nothing else comes out of the radiator.

I've never had a problem with these taking coolant. I can usually get 80%+ of what came out back in. I drive it around for a couple miles, let it sit overnight, and check it again the next day to add any additional.

Well right now the heater core is bypassed due to it leaking, and I probably just didn't get enough back in it the first time chasing leak after leak

[91merc]

A ton of it stays in the heater core and block, even if nothing else comes out of the radiator.

I've never had a problem with these taking coolant. I can usually get 80%+ of what came out back in. I drive it around for a couple miles, let it sit overnight, and check it again the next day to add any additional.

Well right now the heater core is bypassed due to it leaking, and I probably just didn't get enough back in it the first time chasing leak after leak

[91merc]

Ugh, my internet is sucking and I end up with double posts

[Kodachrome Wolf]

Ugh, my internet is sucking and I end up with double posts

Might be the forum. I've seen several double posts in threads.

I've usually just filled the radiator to the top of the core, ran the car with the cap off while maintaining that level until the thermostat opened, then topped off the radiator and overflow tank appropriately. Then effectively do what Tiggie said, follow all that up with a test drive and overnight rest and check level in the morning.

[jaywish]

Normally it would call for about 1.7 gal of straight coolant so I would add maybe 1/2 Gal more of straight coolant before adding any more water.

[91merc]

Another question, how exactly does it draw coolant out of the overflow tank? Does it draw a vacuum or something when the cooling system pressure goes back down after being hot?

[jaywish]

Yes you are correct. When it is hot it blows into the overflow and it sucks when it cools.

[gadget73]

the trick there is the cap must be good, and the hose to the overflow tank can't be cracked or have a bad fit to the radiator otherwise it just sucks air instead of coolant. There are two seals on the cap, the lower one seals to the pressurized part radiator, the spring above that is your pressure regulator, and the top seal is what forces coolant to move in and out of the overflow tank. If the lower one is bad it doesn't build pressure, if the upper is bad it doesn't burp properly.


but yeah I haven't had any particular issue getting air out of these either. If you still have the EGR cooler hoses hooked up, remove one of those while filling the radiator. When coolant starts to come out, put it back on. That will eliminate a whole lot of the air.

Another trick, if you have one of those fail-safe thermostats with the little hole, put the hole at the top of the thermostat. Or just drill a 1/16" hole in a standard one. Same idea, it will let air come out of the block instead of trapping a bubble at the top of the engine until the thermostat opens.

[gadget73]

the trick there is the cap must be good, and the hose to the overflow tank can't be cracked or have a bad fit to the radiator otherwise it just sucks air instead of coolant. There are two seals on the cap, the lower one seals to the pressurized part radiator, the spring above that is your pressure regulator, and the top seal is what forces coolant to move in and out of the overflow tank. If the lower one is bad it doesn't build pressure, if the upper is bad it doesn't burp properly.


but yeah I haven't had any particular issue getting air out of these either. If you still have the EGR cooler hoses hooked up, remove one of those while filling the radiator. When coolant starts to come out, put it back on. That will eliminate a whole lot of the air.

Another trick, if you have one of those fail-safe thermostats with the little hole, put the hole at the top of the thermostat. Or just drill a 1/16" hole in a standard one. Same idea, it will let air come out of the block instead of trapping a bubble at the top of the engine until the thermostat opens.

[sly]

And yes... the forum was having host issues yesterday creating all the double posts. I had to delete one of my own and figured out I could cancel the leave page and then refresh to see my post and that would keep it to one instead of two posts. Happens. We are on a shared host and when maintenance is being done, or other users on the same machine we are hosted on are hogging resources, we have this issue.

Edit: Still having issues. Host may be dealing with a DDOS mitigation. Lots of that been happening across the net lately.