check your coolant elbows, known to fail and slow leak,replace with aluminum elbows,also flush that " death cool" **** outta there with real green antifreeze! dex-cool is Bad!!

 

Your intake gaskets may very well be leaking now. Mine were leaking and the water never hit the ground for a long time. It would pool on the engine and burn off before hitting the ground. It would leak enough that my coolant level would go low and I couldn't figure out why. But after searching hard enough, I found the reason.
I changed the gaskets myself and it was a pretty in depth job but I took my time and it got done, saving me a ton of cash.

 

Hey man, if you know your water pump is still good then you need to buy some radiator flush and get all that brown gunk flushed out of your cooling system before you get that new radiator hooked up. It's rust from your old water pump and your cooling system was never flushed all the way out. Please trust me when I tell you that stuff really needs to come out as best as you can get it out of there. You might need to use a couple bottles of that radiator flush. They sell the Prestone brand at Wal-Mart. Plus, since you just put a water pump on not too long ago, it will wear out prematurely with all that rust going through it. The cooling system on your Monte can be a pain to get all the air out of too. I followed the procedure in the How To Burp Your GM Car thing you were talking about earlier in the thread and it worked pretty good for me. Also, GM v6's are really bad about blowing intake gaskets. If you get 100k miles out of one without replacing intake gaskets you're doing pretty good.

 

Well guys good and bad news..

Everything went fine with the flushing the system and replacing the parts.
Thermostat was definitely stuck open.

Bad news... Coolant elbows are shottttt... Leaking pretty bad. and actually squirts out at high rpms.

We were revving the engine to warm it up and get the coolant flowing. Then we noticed coolant shooting out at around 3,000rpms. From this elbow. http://img109.imageshack.us/img109/2044/dscn1126v.jpg

Gonna get the Dorman aluminum elbows to replace them.

 

I've got an '03 LS with the 3.4 and I don't recall ever seeing that fitting on my engine. Is it only on the SS 3.8's?

 

I don't think you have them. Lucky lol cause apparently almost everyone with the 3.8 v6 is having this problem. There's a bunch of forum posts and youtube videos about this problem.

Search up top for "coolant elbows" then go to page 8 out of 10. There's a thread about 4 down called "00 3.4 coolant elbows"

I tried posting the link but it didn't work.