i have a dodge neon high line with the DOHC i noticed that the reservoir spews out the coolant any time its hot like its got a hole i've had the tank out before and i don't remember any damage to the tank but the tank might be 1/4 full and with this problem coolant goes into the overflow and then on the ground but no coolant that is currently in the tank will go back into the engine when the coolant levels drop. the radiator cap is less then a year old so i didn't think that would be a problem what else is causing this problem do i need to create a new hole higher on the tank and seal off the old hole for the excess coolant to spew from???? any ideas or thoughts would be helpful.

 

The overflow tank itself has an overflow that indeed runs out onto the ground if the level rises above that point. When the tank reaches about 3/4 full - above the full hot line btw - it starts passing anymore then that amount on to the ground. It sounds like a busted tank, because when it cools, it should suck the fluid in the tank back, and if there is an air leak, it won't.

You may have a busted tank if you are not getting fluid levels higher then then 1/4 full before it starts dumping, BUT if your engine is truly overheating, then it may be that you are getting high levels of pressure along with the super hot fluid, and together, it is pushing the fluid out of the tank. However, when it starts cooling down, it would suck the fluid it has back unless there is an air leak - going back to the busted/cracked tank theory.

Does your temp guage show an overtemp condition when your problem occurs? Have you double checked the engine coolent temp sensor to make sure that you don't have a problem there? Does your fan kick on properly? Is it running when the overflow occurs?

Take off the tank and check it out. That is where I would start.

 

I had the same prob and changed thermo and ECT sensor before all that was getting a p0117 (volt to low) once everything was changed the P0117 cleared and then I got a P0118 (volt to high) the boiling issue stopped but now my gauge on my dash doesnt work at all....perplexed!!! and now my power streeing pump seems to be leaking on the bottom of the resevior at the preasure hose. REALLY!!!

 

im having the same problem on my 01.. it gets really hot and the overflow tank gets to boiling. i put water in there and it cools back down. it has happened twice on me in one day. would changing the thermostat help?