I noticed my coolant reservoir keeps overflowing after I drive my car. It does not leak when the car is off, but after I drive the car I notice the overflow all over the area of the reservoir. It檒l overflow to the point that after driving for a bit my coolant in the reservoir will go from the max mark to below the min mark. I try to keep the coolant in the reservoir up to the max level since I believe my mechanic added coolant to the max the last time I got an oil change and I figure I should do the same. I'd like to know why this is happening and what can I do about it? If you believe the problem requires taking my car to the shop, about how much might this cost me? Thank you all for your help!Why is my coolant reservoir overflowing a lot?a bad radiator cap will cause one to do this,it lets too much of he coolant pass by the cap,and runs the over flow jug over on it,id replace that first,its also the cheapest,if that doesn't help it,check the thermostat i it,this may be going bad,if that doesn't help it have a shop look at it for you,the radiator cap may fix this though and they only cost a few bucks,at the worst it probably could be would be a bad radiator or a water pump,good luck with it.Why is my coolant reservoir overflowing a lot?When the engine is cold the level should only be about 1/2 way between the min and max marks, if you fill it to the max it will overflow when the engine heats up and the coolant expands. Also make sure you are adding a 50/50 mix of coolant and not straight antifreeze.Why is my coolant reservoir overflowing a lot?!; Max Level means %26quot;full level then engine is at or just above operating temp. Min. level means; Normal level when system is cool. only fill to this level IE; %26quot;min.%26quot;
2; does the engine get (Not hot) warmer then normal? Radiator cap could be bad (Check for rust inside of cap)
3; Thermostat could be starting to stick only half way open, easy in expensive fix.Why is my coolant reservoir overflowing a lot?I made the same mistake and found out from my mechanic you need to leave some room in the overfill for the radiator to be able to pump into, the thing is coolant expands when it heats up. Just leave to overfill for the coolant at half that way if the radiator needs it can pump into the overfill or take some out of the overfill. And the reason it isn't doing it when its sitting is your engine isn't getting hot so the antifreeze or coolant is just sitting in one spot. Good Luck I hope its just that if not it could be a bad radiator cap or overfill cap
