1995 chevy camaro Z28 overheating
 

Hi, I have a 1995 chevy camaro Z28 it fills the overflow tank very fast is no leaks at all and I change thermostat, radiator, hoses and still doing, I check compression leaks and nothing.

Did you replace the radiator cap?

Hi, thank you for reply, yes I did replace the radiator cap radiator, hoses I try with thermostat and with out and the problem persist I did pressure test and no leaks I did combustion leak test and nothing.

There is a steam/coolant return hose and reservoir hose that can get mixed up. Make sure they are in their proper place. Return hose goes in 2nd port below rad. cap and reservoir hose connects to port directly under the rad. cap. If you know those two are in their proper place then there is a good chance you have a blown head gasket. You can rent a coolant system pressure checker from any auto parts store. Put no more than 19psi into the system and watch the gauge to see if you're losing pressure. If you are, take the plugs out, do the test again, rotate the engine by hand with the plugs out and see if coolant starts pouring out of one or more of the plug holes. You can also check the spark plugs to see if any one of them looks cleaner than the rest which is a direct result of it/them being steam cleaned during the combustion process.

Hoses are in a correct place and yes I did the pressure test and check the cylinders is ok

Have you followed a step-by-step guide to bleed any trapped air from the system? How long does it take to overheat, and does it do it when the vehicle is stationary, when it's driving or both?

Yes I did several times to bleed and it gets hot as soon as the light for coolant gets on because is low and fills the overflow reservoir tank

How dirty is your cooling system?

Do you have the part number for the thermostat you used?

are the coolant fans coming on on the first stage

Hi, is not dirty at all I even check the heater core and is clean this car is making me crazy, I can't find nothing wrong but still overheating

The cam driven waterpump on the LT's is a pain to get to, is it pumping enough coolant at idle?
Does the car cool down/stay cool going down the road?

Yes is pumping enough coolant I try with out thermostat to check and yes is pumping good, I live running at idle for like 30 minutes and then I drove like 18 miles and the light for low coolant gets on I wait to cool down and check and the overflow tank is full radiator empty.

The cooling system is very simple. If your reservoir is overflowing then the coolant is taking the path of least resistance propelled by pressure. So, either the hoses on the tube/reservoir into the radiator are switched around, or your radiator cap is weak, or the cap is fine, but gives way due to the coolant becoming too hot because it is not being properly cooled down, or you have a blown head gasket and excessive pressure is being built in the cooling system and radiator cap is giving way and coolant is escaping into reservoir.
Checked your oil lately? If it's a chocolate milk-like color then almost guaranteed you have a blown head gasket or cracked heads/block, however the path where a head gasket can fail may only find its way into a cylinder and not into the oil.