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Why would coolant level drop from max to min but then stays at a steady level ?

I replaced the coolant expansion tank about 1 week ago, I bought a used one from car salvage shop , cost the same as brand new one but needed it there and then so just got it.
Old one was leaking I think as there was water underneath it and I could see trail of water from car, also when I re filled old bottle it would be empty within minutes,

Now I have put replacement expansion tank on and I can no longer see water trials from the car.
Question is, when I topped it up I topped it above maximum line, then 2 days later I check and it is a minimum line and it has been on minimum for around 1 week with no further drop, it just seems once I add water past maximum the water level seems to fall to minimum, but then stays steady at minimum with no further water loss ?

Somebody said it could just be the expansion bottle getting rid of excess water,but my old bottle held higher amounts of water before it began leaking and it stayed steady ?

(edited 8 years ago)

Reply 1

Talon

Probably just air in the cooling system that has now been forced out as the pump has pushed the water round. Also, don't fill beyond the maximum, fill up to it, and top up later after running the engine (if required).

Reply 2

I love life

Original post by Talon

thank you

Maybe that is the problem, will have to wait and see, I actually filled it to max line for the second time a few days ago and it dropped to minimum.

any ideas ?

ty

Reply 3

JC.

Leaking system didn't pressurise.
New system is capable of pressurising so ejected what it didn't need out the overflow.
Now it ejects and sucks back in what it doesnt need / needs into the expansion tank like it's supposed to.