I have a 98 Neon DOHC 2.0L engine that overheats after about 20 to 30 minutes of perfect driving. I have replaced the water pump and radiator with new, not rebuilt, parts. I have removed the thermostat all together and bought a new radiator cap with pressure release. I removed the thermostat because it was overheating with it and I thought that might relieve some of the pressure.

What is happening is the cooling system is building up a lot of pressure and causing the water to evaporate. The car then overheats and I have to stop and flip the pressure release on the radiator cap because there is so much back pressure. Once the water blows out of the cap release, I refill the cooling system with water and it will again run cool until the pressure gets so great and the heat gauge is all the way up and I start all over again. I have tried using coolant, thought that might help but same thing happens.

I carry 2 full bottles of water if I am going to drive any distance and as long as I relieve the pressure and put in fresh water it will run perfect. But the built up pressure is so great that it blew up my previous radiator, which is what forced me to buy the new one.

I don't have any water in the oil or any smoke coming out of the exhaust. The car runs like a dream until it starts to overheat.

Any help or suggestions with what you think might be the problem will be appreciated.

 

take it to a shop and have them pressure test the cooling system. IT really sounds like you have a leak somewhere thats letting the water boil. Make sure you check the heater core hoses that are infront of the engine for any sign of a leak, the smallest hole can be a big problem.

 

one you need to add coolant to the water as it raises the boiling point as the thermostat doesnt open until it reaches 195 water boils at 212 and it also help prevent corrosion in the system second you might want 2 check your fan relay it will keep the fans from going on there is also a recall on the fan relay for certain 97 and 98 that were made in toulka(i think or someplace that begins with a T) not janesville google it

 

maybe one of the passages is cloged?.

 

You dont have a thermostat? The coolant pressurizes to a certain psi for a reason. Without the thermostat I am sure its not working right.

 

OK here is some new info on the problem - I replaced the thermostat, thermostat gasket and thermostat housing. I also added 50/50 coolant in the engine and only coolant to the reservoir. Having done all of that the car still overheats.

I did find out that the coolant is being force out of the reservoir when the car overheats. The reservoir coolant is boiling and forcing the coolant out of the overflow tube. Why it overheats I don't know. New water pump, new thermostat, new reservoir bottle, I don't know what else to do. Any ideas will be helpful?

 

like i was saying before, either take it to a shop and have them pressure test or buy your own kit and do it yourself.
http://cgi.ebay.com/ebaymotors/Stant...spagenameZWDVW

im betting its an internal leak
http://www.aa1car.com/library/coolant_leaks.htm

 

But doesn't the lack of smoke from the exhaust and the engine running good (except overheating) rule out an internal leak from the head gasket or a cracked head/block casting ?

 

water doesnt smoke

 

OK water doesn't smoke except white steam if it's a bad enough leak. I suppose the cat would reduce the vapor to a point that there would be no billowing clouds of white smoke/steam. But the oil should get contaminated also shouldn't it, if there is an internal coolant leak ? Also wouldn't the remaining coolant get contaminated with oil ? When I've encountered a bad head gasket it is usually accompanied by coffee colored milk-shake consistancy, oil and coolant. Admittedly I have not seen a Neon with a compromised seal between the engine and block and cooling system ... maybe.

This thread caught my eye because my Neon is experiencing some coolant contanimation by oil somehow, although it is not overheating ... finally. Can these engines leak one-way whereas the oil does not get contanimated with coolant but the coolant gets contaminated with oil, in the event of a head gasket leaking or a cracked block/head ?

I'll be keeping a close eye on the ATX fluid until I figure this one out on my own car.