I have a 2005 Monte Carlo SS supercharged with the 3800 series. The problem I'm having is I just did a radiator flush then stuck a cleaner in it for 3 day's, because when I had opened up the radiator cap before I did all of this I found this brown oily thick sludge in it. I just figured that at some point some one had put some type of sealent in it. So I got everything to finally flow out clear, I then went to put water in it just to let it run at normal temp for about 10min but as i was I noticed that the radiator just would not stay full. I looked under the car and noticed that it was leaking so I thought I just hadn't tighten the drain plug all the way. I went under the car and seen that it was coming from this round hole that is on the very bottom and there is another one in the same place on the passanger side of the radiator. I have no clue what these are or how to fix this problem. Can ANYONE out there help me out please and thank you.

 

there is only one drain plug on these radiators. it might be cracked down low and the leaked water is running inside the rad support. have you removed the radiator from the car to see where the leak is? if it is in the plastic you might be able to use JB weld or quick steel epoxy to repair it. I had a leak in my old radiator that i sealed with the epoxy and it lasted for 3-4 years. i had found a good radiator at the junkyard and had it for over a year before installing it cause the repair had worked.

drain it, remove it, clean and repair leak, let dry, refill it the next day and you should be good. I liked the quick steel epoxy cause i made a big flat patch about 1" past all the edges of the crack.

either this or just find one at the junk yard and replace it.