Ok, so i have been reading through all the overheating threads and couldnt seem to fins a problem like im having....so heres my problem, sorry about the length,

Its a 1995 Z28 w/150,000 miles:

My car has been fine, cooling system wise, bright green coolant, filled to the top. Just recently when i was driving while sitting at a bank-line, my temp. jumps up to 250 degrees. The weird thing is that when i turned the heat on to cool it off some, the interior became full of steam and coolant smell. Most of it comes from the vent on the top of my dash-pad. There is no smoke or steam coming from under the hood AT ALL. So i went to a gas station, took the rad. cap off and I was about empty of coolant. Looked under the car and there were no leaks or anything. For the last two days I kept driving it for short trips trying to find the problem. It heats up to the 250 deg. after about 10 min. of driving w/heat on high but no overheating from under the hood, just inside, but keep losing coolant somewhere, somehow??? Car does not smoke out exhaust, has full power and seems to be ok. I was told my WP might be bad but doesnt seem to be leaking anywhere, could it be the WP....Any help or advice on this I would greatly appreciate, especially since I have started taking it apart already today. By the way, after draining the fluid, the coolant was rust colored and full of dirt and tiny pieces of hose, so i kno i need a good flush but my main thing is whats with the leaking and high temp all the sudden??? Thanks again 4 any help what-so-ever!

**Also, not sure of any tune-up or maintenance work done as I just recently bought the car about 6 months ago.

 

Sounds like your heater core may be leaking. Is the carpet damp in the passanger seat area?

 

+1 for this suggestion too
my car would start to over-heat, and it was a blocked heater core. you could have a hole in a line somewhere

also, check ur thermostat

 

heater core is leaking, not too hard from what i understamd

 

I did not even think about that, will definently be the first thing I check out in the morning, got to have light. Hopefully thats all it is. **Does anyone have a diagram or something showing me where and how to replace it. or can you just tell me. Prob really easy just have never done it before, thanx again

 

i know on mine, we just had to pull out the glove box, and undo the airbag so it wouldnt go off, and there was a little cover over it, not too hard. theres a write-up on here somewhere, or google "lt1 heater core"

 

Yep, the heater core was leaking and also SOAKED the inside of my car. Thanks for the much needed info, but i had one more question....after i put the new heater core in, i let the car run and the temp. gauge still keeps climbing to the top??? No smoke, leaks and heater core isnt leaking i dont think because there is no more steam coming through the vents either. Just temp wont stay down. Also put in a new thermostat when i was doing it and its the stock 180' stat. Just scared to drive it with the temp. jumpin like that after only sitting for a few minutes. N E ideas?

 

ALL FIXED!! Everythings good now, i guess the thermostat that i got from the parts store wasnt the right one, just didnt look right either even tho it was listed as a 180'. Put back in the old thermostat and bleeded the coolant system and everythings great now!

Thanks again for the help everyone...i'll be sure to help out when i can