well i finally got my car to sit and idle today (new 350) well i had it idleing for like 10 minutes and i look over to see the over flow tank for the raitor starting to bulge, well then froth starts to pour out of it and starts to boil. what is my car heating up so hot, i dont have the theromastat in yet, and i dont have the temp gage hooked up since i tookk off all the cencors. thanks

 

Belt driven fan?

 

Check and see if your waterpump needs replaced

 

Check and see if your waterpump needs replaced

 

Live long enough and you hear and see it all. Why in the world would you not hook up the temp guage on a new engine? If you are expanding the recovery bottle system pressure is way high. What belt setup are you using, remember with serpentine the pump is reverse rotation. It sounds like the coolant is not circulating. Another possibility is the system has a lot of air, make sure it's bled. I would make darn sure I found the problem, that's no way to break in a new engine.

 

Take it to a shop that can fill the system with a vacuum pump. That is to say (like the previous post), it will eliminate any air pockets from the water fill up.... Which it sounds like is a possibilty in your (and mine) case.