I have a 95 XJ 4.0. Whenever I check the coolant overflow tank, the level is all the way at the bottom... there's just a 1/2 inch or so, well below the "min" mark. I'll fill up with 50/50 to the top of the reservoir, and the next time I drive and park, coolant is spilling out of the tank like crazy. Once the coolant gets back to its low low mark, that stops. I never overheat.

So it seems like my jeep does not want any more coolant than what covers the bottom of the reservoir -- any more and it spits the extra out, even if the extra isn't even up to the proper mark on the tank. Does that make any sense to anybody? Should I ignore it?

 

Is there a mark on it that says hot level on it,you are not suppose to fill them to the top,there has to be room for exspansion as the engine gets warm. When it is warm the level will rise,and cold the level should drop. I would just add a little each day until you find where it wants to be at without overflowing.

 

get a new cap

 

I assume you mean a new radiator cap -- but do you mean reservoir cap?

Thanks for the help folks.

 

no, just find the level where it wont overflow after you drive it, i did this once, it should say where t o fil it to on the resivior bottle

 

I fill it to the correct mark on the reservoir bottle; the lower mark is the cold mark, but I'll fill it up to the hot mark in case. After I drive awhile, the level is well BELOW the cold mark (even when hot), but I can't find any leaks and the car does not overheat or appear to suffer any of the effects of low fluid. I can drive it a month after it reaches that low point where the coolant barely covers the bottom of the tank, and it drives fine. So it seems to hold onto coolant, but not enough coolant to make the mark. That's what's confusing me.

 

A bad radiator cap will cause your over flow bottle to over flow. Replace your radiator cap.

 

On my way to get a radiator cap. Thanks again

 

yes radiator cap