Where is my coolant going?



99 dodge Neon, 130,000 miles, 4cyl Single Overhead cam, stickshift

I have been checking my coolant levels every other day and the coolant in the Resevoir Tank keeps going down.

I had it pressure checked by two different shops and they both said it was fine. Nothing wrong that they could see.

Any ideas why it is losing coolant? I am afraid to let the coolant drain all the way from the Resevoir Tank in order to see if it over heats (then take it in to a shop saying it is overheating. thinking that could help figure it out.)


It is possible the resevoir tank has a crack in it and the coolant is slowly leaking out. It could be spraying out under the car as you drive so that you do not see the “puddle” under the car when you stop. They probably pressure tested the radiator and eng. block but not the Resevoir. Check the level in the resevoir in the evening…mark the level on the outside of it. Then check it the next morning to see if it has changed any. Or if you can remove the tank from the eng. compartment you may be able to see the crack visually.


Agree with the reservoir comment, also check or maybe change the radiator cap and also check the tubing between the radiator and the overflow reservoir.


[b]Have you kept an eye on the oil to make sure there isn’t a head gasket leak?

Pull the oil dipstick out to make sure the oil looks normal.



I had a new head gasket put on 2 years ago. It blew and i got a new head as well.

what does a pressure test do? why is the radiator ruled out? and what makes you all think it is the resevoir tank itself? i am just trying to learn here and see why you all rule out major problems.



Don’t look for major problems until you eliminate the minor ones. The radiator cap (the one on the radiator, not on the fill tube or bottle) can fail to hold pressure and the coolant can boil away easily. You might even hear it after you turn off a hot engine. Don’t take it off, just listen for bubbling noises. It’s easy to replace, cheap and available everywhere.


so the only way to tell if its the cap is if it sounds like it is boiling? does it always do that? or are there other symptoms??

i can buy one of those for like 5 bucks i think at autoparts store.