ok, let me fill you in on whats going on here. was driving home yesterday morning from work. about a mile into the trip i noticed that the low coolant light had come on. so naturally, my next reaction was to glance down at the temp gauge. at that point i noticed that it was starting to heat up way past normal temps. especially for just being started in such cold weather. so i stop the car and checked the coolant overflow container, was running a little low so i decided to do a quick turn around and run back to the fire station that i work at. it got up to 3/4 on the gauge at which point i was about to shut her off when i noticed that the car started cooling. at the same time, my passenger friend observed that the defroster was now blowing warm air (it wasnt previously with the rising temps). i slowed down for a minute and contemplated the return trip home when the car made the decision not to for me. it had started heating up again and the defroster was again blowing ice cold air. after a couple stop and goes, i made it to the station and made the decision to pull the thermostat. although i knew that that shouldnt have been effecting the defroster, was the only thing i could think to do. took about twenty minutes and started it back up and was running extra cool (for obvious reasons) but would have to do until i got back home and do some inspecting. i also took the time at the station to top off the radiator and overfill container. after 30 miles of driving, i had to drop my friend off at his house before i could get home. as i was backing out he noticed that there was a little bit of water in the driveway. the engine was still cool, so i just decided that it was possibly water overflow from the resevoir. until about a minute later when the engine started heating up all over again. back in his driveway, i pulled the cap to the radiator to find that it was low again. so we filled it back up and let it run in the driveway for approx. 20 minutes while watching the temp and watching for anything leaking underneath. not a single leak was discovered and temp stay in normal idle levels. got the car home and was a little low on coolant again. so, one of the obvious answers here is that i have a leak. but from where? (obviously you wont be able to answer this, unless someone has a suggestion as to where a covert leak could be hiding.) and why did the car at one point start cooling itself off again and the heat returned to the defroster? sorry about a long post, but felt it very necessary to be thorough. also, quick add: the radiator is no more than 4 months old and heater core is approx. a year old. no signs of leaks in either. could this possibly be a bad water pump? wouldnt makes sense if it was. but i'm totally baffled. let me know if you need any more info . any help would be appreciated. thanks guys.
dave
97 TA 6sp 125k miles (40k on replacement stock motor)

ps- i also checked the oil and exhaust for any signs of a water leak inside the engine. oil looks perfect and no discoloration in the exhaust gases.

 

Head gaskets...you are burning the coolant in the cylinders.Getting air pockets causing the cold and hot air in the defrost.Good luck.Also,I wouldnt drive it anymore til its fixed.you will cause more damage.

 

ok the answer for the heating up and cooling down is an airpocket. an airpocket has gotten in the system causing the system to not flow properly and causing it to heat up till the pocket moves allowing it to flow again. it usually results in the overflow tube filling up then overflowing to realese some of the air. The cause for the airpocket is two things. One you have a leak in the system. since you did not see any visible leaks i am almost sure it is a head gasket. if you open your oil cap and it looks kinda milky that is a good sign that it is a head gasket. There are a couple of other things it could be but i would first try to bleed the system then let it sit at idle to see if it stays at opperating temp. if that does not solve the problem i would start looking at the coolant system itself...making sure your cap is still good to checking on your thermastat to the waterpump itself. I would suggest trying not to drive it if possible only b/c you can cause major damage but i drove around for 6 months with a blown head gasket just make sure it never gets too hot

 

what about fans? mine did the same thing when the fans were cutting off....

 

Mine did the exact same thing almost.

It got to where it would be fine if I let it cool off and started it, but hot starts required me to purge the system.

It was a BLOWN HEADGASKET. On the back of the drivers head leaking into number 7.

I never got any smoke or any of the obvious signs, execpt what you are seeing.

I replaced everything trying to track it down, even pressure tested the system and it checked out fine . Nickel and dimed me to death between thermostats, rad. caps, cleaning radiator, and blah blah blah.

Let us know what ends up happening.