1987 300zx non-turbo over heats
 

hi im new here and cant figure out why my car overheats quickly and is always empty on coolant after i fill it and let it run or sit for a while. so far i've checked the radiator and checked for cracks.

go to autozone and rent one of there cooling system pressure testers and try that and if the cooling system dosen't hold pressure then you know whats up just make sure you do it dry so you can look for wet spots

If your always out of coolent it has to he leaking somewhere. I would have to say your water pump is no good.

Great. Another idiot who can't use punctuation and grammar. Seems to be an endless supply of them lately. And notice they all seem to have heating/cooling issues?

Stay in school.
Pay attention in English class.
Learn to post intelligent looking posts with punctuation. You'll get more/better help that way.

If you're losing coolant and you can't find the leak, I'd suspect a blown head gasket.

Z31 overheating
 

My overheating problem went away once I replaced the radiator, added a thermostat, engine flush, etc. I am a happy camper even though it cost me $400.

I replaced everything on my 88 related to the cooling except for the head gaskets. Could be leaking out of the thermostat as well. It's very hard to tighten all of the bolts up for the thermostat unless you have a universal joint/knuckle. Maybe (and I don't know much about the history of your car) the tech/person who replaced the thermostat (or it's never been replaced) didn't get it all the way tight.

have you gone to autozone and got the pressure tester yet? and for az-zbum's suggestion does your oil look like chocolate milk(bubbly)? cause if it does then it's the H/G

if you don't see it leaking on the ground then it is going out the tailpipe by way of a blown head gasket. leaking water pump you will see it on the ground (under the car if you haven't figured out gravity yet)

You most likely just need to bleed the cooling system. Probably need to check the fan clutch too.