I just put in a heavy duty aluminum radiator, water pump and 180 thermostat. No leaks. I drove the car for about 25 min, and came back to the house, when the radiator was overflowing from the insert by the cap. whats that mean? any help. I checked the thermostat is correct. and installed right. anything else?

 

"Insert by the cap"?? Explain

Is the system purged of air?

 

there is a small rubber hose by the lid that leads to the overflow tank. but I dont have a overflow tank. so the pressure and coolant flows out when hot.

 

Sounds like you got an air pocket in it. Did you fill it, run it up to temp, (when the therm opens) and fill it the rest of thee way? If not, that's what you need to do.

 

That is totally normal. Your radiator is designed to work with an overflow. This will allow the coolant to expand and run into the overflow. When it contracts it sucks it back in.

Your present set up is expanding, which is normal, and falling onto the ground. It tried to suck it back in "from a bottle" but yours is disconnected.

If you insist on running it without a bottle like they did in the 50 years ago in the 60's. Then you need to run the coolant level not filled to the top to allow for expansion.

 

Make an over flow bottle out of something, pretty easy to do. You might replace the radiator cap too if its been on there awhile.

 

You can't run at a drag strip without a coolant overflow can. They're funny that way, about people getting greasy antifreeze all over the track.