so i was bored,, looking into buying a 4th gen as well, and i read some cooling issues,, heres the question on my iroc-z ive been loosing coolant out of the resivior for 4years now,, no white smoke, no visible leaks, no foamy brown water in oil,, only thing when i start it i get some burnt oil just a quick second,, where the hell is the coolant going lol,, she sat from october till this month driven twice!! filled the whole damn bottle back up wierd!!!

 

Is your rad filled up all the way? Could be that your cooling system wasn't full up all the way, and sucked coolant from your reservoir to fill it up.

 

its been doing this for 4 years now??? has to be losing it somewhere

 

The coolant resevoir is not air tight. Water evaporates. Add those 2 factors + time and you have your "coolant leak". In reality, its most likely the water very slowly evaporating off, and concentrating the coolant mixture.

 

you want to open radiator when car is cold,fill it up and let it run until thermostat opens keep it full until it opens atleast three times then put cap on and refill overflow then see how that does.
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85' IROC 305 tpi stock (for now)

 

if the water is really evaporating out, get a hydrometer and check the freezing point or boiling point of the mixture, i wish i could remember the freezing point of pure coolant