I was on the highway at about 3 pm . It was like 94 degrees out and sunny. I was getting on it pretty good showing a golf what my car can do. Well when I got to around the end of third gear i looked at my water temp gauge and it was almost to the red. So I pulled over and let it cool down and looked in the engine bay. My coolant reservoir was boiling like crazy. After a few minutes I started to drive it back home about 4 miles away. It seemed to be alright when I was moving but when i would stop it would get really hot. And when I was driving the temp would go up and down pretty fast. It was fluctuating a lot. Well I let the car sit over night and figured I would mess with it in the morning. This morning I looked at it and the reservoir was empty and there was all kinds of greenish brown slime in it. I cleaned the reservoir out and I filled it up and took off the pressure cap and started her up. I added some water while it was idleing and I revved it a little and added more water. I just got back from taking about a 6 mile test drive in it and it didnt get hot at all. I guess I am going to flush it out and see if that helps it. Maybve it was just because I was getting on it pretty hard on the highway. I was boosting a little to get the temp up on my test drive but I guess its working OK now because I didnt see it get hot at all.

ya might have something wrong with your radiator FAN. if it's getting hot when you are sitting and cooling down when ya are moving, I'd check to see if the fan is comming on. And also check your antifreeze/water ratio, it shouldn't actually boil over and shit like that if you have a good 50/50 ratio of antifreeze and water.
I'm thinking you could also try and check to see if you have a clog in your coolant system.. perhaps it's just clogged enough that when the water pump is reved up, it doesn't have enough power to push enough water. <-- that last thing is just a guess.. I'd look at the first thing first.

I 2nd that checking your water to coolant ratio. I fucked that up once and not only did it overheat the damn water boiled and evaporated til I didn't hardly have any in there. The fans should be obvious already if they aren't coming on, if your temp is in the red they should be on. Also wouldn't hurt to have your radiator checked for clogging. If your radiator is hot on one side or one area and cool in another you might have a clog. I did and got it snaked for about $100+ or so including labor to take the radiator off.

When my radaitor was clogged it did the same thing: temps cooled down once I got into motion, sometimes got a little hot while stationary. Good guess on the last one.

I'd also boost the piss out of it in the higher gears to test if it's gonna overheat. Mine with my bad headgasket only overheats when I boost it hard in third or fourth gears. Make sure your not pissing antifreeze out of your overflow. Keep us updated...I'm sure it's just something little :)

water to antifreeze ratio? I doubt that would do it in the summer time.... Cause I dont use antifreeze till the winter... I just run pure water and a bottle of water wetter.

it could be the thermostat going bad...did you check that?

>water to antifreeze ratio? I doubt that would do it in the
>summer time.... Cause I dont use antifreeze till the
>winter... I just run pure water and a bottle of water
>wetter.

Trust me it can happen. With water wetter you dont need anti-freeze but they dont recommend running that way except at the track. I didn't have a thermostat in at the time which made matters even worse but pure water and not enough antifreeze without water wetter can boil off. I drove 1hr and 15 minutes with no problems. Then 45 minutes on my way back it started to boil over.

yeah.. no antifreeze in teh summer is a bad idea.. since antifreeze also helps cool the car and not just keep it from freezing. you get a good 50/50 ratio and your coolant won't boil till like 300 degrees.. instead of the 210 of water by itself (which the coolant will get to without a problem on any summer day).

water wetter is a different story since it's basicaly a better 'antifreeze' that helps with the coolants ability to transfer heat in the radiator (for cooling) and in the block (to pull the heat out of the metal).

so... in any case.. if he's just adding water everytime it's low.. his ratio is gonna have too much water and boil easy and not cool down the motor as well. especially if it's mixed with other cooling problems (like clogged pathways or bad fans).

antifreeze itself doenst cool the engine, it actually denotes cooling a little. All antifreeze is really for is to raise the boiling point of the water, higher than just plain water, which boils around 215-220 degrees I believe. In the winter, antifreeze also lowers the freezing point of water, to negative degree temps..Water wetter just gives normal watter more thermal conduction properties. So yes, no anitfreeze is bad no matter what time of year, but if you run watter wetter with plain water, that may be ok. Most antifreeze also has lubrication properites added to it, to help the water pump from over heating and siezing up.

Well I didnt flush my coolant today but I drove the car around wuite a bit. I figured out that it only starts acting crazy when I boost it really hard. I made a few hard runs today and when i boost 15-16 psi and stay on it for a while the coolant gauge will go up really fast about 3/4 of the way up thne it will dfrop instantly when I let off the gas. It moves much to fast. I dotn know how the temp can be changing that fast. There is no way it can go from 3/4 of the way hot and back to just a little under half way in like 1 second. I am going to have my friend that works at tire kingdom flush it with the machine on tuesday. I am not sure what kind of mix I have in it but I do know that the water is green so it cant be too much water. It should be just right. I only added water once. Another weird related thing with it is that my heater wasnt working when I tyried to use it a few weeks ago and now it works. I think its kinda strange that it would not work one week then all of the sudden it starts working again. I dont know exactly how heaters work but I know it uses the coolant to make it hot.

BTW...I was hitting 16.5 psi on the way home from my friends house tonight and it felt soooooo fast. Its such a big difference when its 95 degrees in the day to when its 75 degrees at night. I think I am going to have to get new tires hear pretty soon if I keep spinning the damn tires in second gear so much. }>