I want to do tb bypass when i get home, i dont recall seeing **** valves on the ls1. Do i need to bleed the system after, or does this cooling system do it by itself?

 

It needs to be bled.

My old car needed to have a special procedure done to be bled and unfortunately I didn't know it. I didn't want to make the same mistake with my car, so my mech. has a special machine that bleeds the system perfectly every time.

 

My LS1 had no problem with the same method I've used for my 88, fill radiator with coolant while its running, close cap, let temp go up, let temp go down, cycle a few times, fill again if necessary when cold. Ensure your overflow has a good level of coolant.

I did the TB bypass last year and was driving it around today and temps were just like I remember when I bought the car.

Usually air in the system will cause the car to overheat a bit, my 88 is a conundrum. It takes forever for it to get to temp (forever being I could drive 20 mins and still be below operating temp)... I think I went a bit overboard in my cooling upgrade for that car lol

 

Oh god, my 94 3.4L was the same way. In the winter, forget the heater. i put in a 195 stat and it STILL would never even regester on the guage unless i let it idle for 30 min. i had an aftermarket pump, and a quality all aluminum radiator.

 

The proper way to put coolant in an LS1 is to fill it with the engine off and a TB coolant hose off. When coolant comes out of the hose, the engine is filled. Reconnect the TB hose or your bypass and fill the radiator. No need for "burping" the system. The 3400 in my wife's 01 Grand Am fills the same way as I'm sure most newer GM engines do too.

From this point, I'd run it and check the level after it has been running at temp.

Had a local shop flush my system while it was getting the oil changed. They tried it w/out unhooking my tb bypass hose like I told them. It wouldn't take much coolant. Long story short. They called a GM dealership, and were told to do it the same way I told them to do it. It cost them too, they had to replace my water pump after the dumbasses over heated my engine and it started leaking.