Hello,
This is my first post here. I am totally confused and I need some help diagnosing the problem. I would greatly appreciate any suggestions that you might find applies to my situation.
First I would like to qualify myself as a low-end DIY auto mechanic. I am a computer tech and my hobby is woodworking. I can handle minor repairs competently but if a job requires special diagnostic tools or advanced skills, I do not hesitate to defer to a pro and pay for the service.
That being said, this 1983 camaro z28 has been in my posession for 4 years and I have sunk a lot of cash into keeping it running.
I suppose that the readers of this post can relate to that.
It has been sitting for about 6 months because I believe that I could perform the repair if I knew what to replace. Plus I need to save cash if possible.

Here is what I know.
Motor = 305 Cu. In. Overheats very quickly. Within 3 miles even cold weather.
Replaced so far:
Clutch Fan
Thermostat
All fan belts
Upper radiator hose

Known issues:
Does not pull fluid from reservoir
Small crack in radiator on top (about 1/2 x 1/32 inch)
When the engine is running, I pull off the cap and add water, it seems to pulse or ebb and flow inconsistently.

Water pump does not squeal.
Belts do not squeal.

I hope that I have provided enough information here to give anyone an idea what is wrong.
I will check back here regularly to respond to any questions.
Thanks in advance for any help.
G

 

check the Thermostat to see if its functioning properly ...
you could remove it and see if the car still over heats .... or get the thermostatt to operating
temperature and see if it opens

 

Okay, I will do that first thing tomorrow.
Let you know what I find.
Thanks!

 

The crack in the radiator prevents the system from building the pressure required to keep the coolant from boiling. Boils, blows coolant out of the system. As the system cools down, if there was no crack in the radiator, a vacuum would develop and pull replacement coolant out of the reservoir. But, the crack prevents the system from building a vacuum.

Fix the radiator.

 

The water pump has a 'stamped steel' impeller, and are known to rot away, so no flow of the coolant. Also, as Injuneer stated, the cracked radiator aloow's the coolant to leak out and air sucked back in when cooling. Get a new one, they can be had for $100 at your local Advance or Auto Zone store. Water pump's are cheap, too.