Coolant overflow tank

[helper_learner]

Overflow means the expansion tank fills up and then extra coolent come out?

[helper_learner]

If it happens the only possibility it that you have change radiator with a larger radiator...

[frozennova]

I'm seeing some liquid on top, but coolant level keeps dropping slowly too.

[frozennova]

Yes I've seen it near full with extra coolant outside overlfow tank, then when car cools the level decreases slightly more than last time it was cold.

[Xulfiqar]

This phenomenon is called evaporation.

its normal, I believe you are only adding 10 or 20 ml at max. which you dont need to. The level between cold and hot has more than enough capacity to take up these slight variations.

what mix ratio of coolant to water are you using?

[helper_learner]

Yes it is but he is saying

"I fill it between max and min line"

I dont understand why there is so much expansion...

I think he should keep very very low level in expansion bottle
And @frozennova there is no need to change bottle it is perfect...

[frozennova]

50 50 Aisin coolant.

On my first drive I've had no spillage since changing bottle, it has a slightly different cap than the last one, otherwise the same.

[Xulfiqar]

the level should be kept at the "low" mark on a cold engine. it should rise up to the full mark with hot engine.

[frozennova]

New bottle and cap seem to be good. First drive and no spillage, I guess time will tell.

[Xulfiqar]

you bought 50/50 coolant, but how do you know that you have a true 50/50 in the engine/heater/radiator system if the system was flushed with water earlier.

This is why I advise to buy concentrated coolant.

[helper_learner]

Hmmm

[Xulfiqar]

mhmm

[helper_learner]

Hoping that it works fine...

[helper_learner]

Update?

[frozennova]

Didn't leak when filled to about middle of tank, so I added some more to experiment and it started leaking.

I think it's better than previously though.

[helper_learner]

Good to hear thar now you poblem is solved...

Don't fill above middle if it is working there ..

[fusion.alive11]

Does a minor leakage like a pin hole in the cooling system cause the reservoir bottle to overflow?

I do understand the theory that it could suck in air which causes pressure and air bubble/pocket to form, what I don't understand is the coolant system is pressurized when engine is warm/hot so instead of sucking in air it should push the coolant/water out of that pin hole instead of sucking in air so how does that contribute to overflow of reservoir bottle?

[helper_learner]

When the coolant overflow and after cooling is there less coolant in radiator?
I think I you case it is not...

what I don't understand is the coolant system is pressurized when engine is warm/hot so instead of sucking in air it should push the coolant/water out of that pin hole instead of sucking in air so how does that contribute to overflow of reservoir bottle?

It never sucks air when it is hot ... when coolant is hot it expands and causes the coolant to go in coolant bottle...

and then coolant cools down then it contracts creating vacuum and then it suck air from pin hole leak if any....

If coolant is less in radiator then there could be leak else not...

[Xulfiqar]

If a minor pin hole leak exists, it will seep out too, and will cause air to be sucked in when system cools down as air is lighter than water.

[helper_learner]

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