Gearhead6s

Just got my turbo 355 LT1 car started yesterday for the first time in 2 years, man I am happy. One of the few small problems I encountered was the overflow of coolant out of my overflow can. I have a Griffin radiator and a summit catch can that does not reserculate. I "T"ed the head steam pipe and the overflow into the radiator neck nipple. I was wondering if it is at all possible to delete a catch can/overflow all together and just run a closed system with the steam pipe directly to the radiator? I understand that the pipe on the heads bleeds the steam out but if you ran a closed loop would it not just fill with coolant and run like rest of the system? If I could bleed all the air out of the system at the screw on the water neck would this work?

Evil Eric

if the steam pipe flows (is t'd) into the catch can you will eventually pump your coolant system dry.

Gearhead6s

That's what I learned last night, when I had to open the valve on the can to get the coolant to the bottom of the car instead of under the hood. So do you think I can run the steam pipe straight to the radiator and be okay?

OBE1 95Z28

On my 95 the steam pipe does connect directly to the stock radiator as it has to in order to pressurize the system to 18 psi. Only the overflow line goes to the catch can which is vented to atmosphere through the holes in the screw on cap.

Gearhead6s

I only have one nipple on the radiator and no other way to run an overflow/vent tube other that they way I have it set up. I am curious of the negative affects if i were to delete the overflow/vent all together.

Injuneer

The "steam" pipe does not flow "steam".... it may occasionally allow air bubbles or small steam bubbles to leave the back of the heads, but normally it flows coolant. I have a temp sensor in the line, and the coolant is the same temp as the other two sensors in the system.

The 93-94 cooling system is routed with the "steam pipe" going directly to a connection on the passenger side radiator tank. The 95-97 cars route the steam pipe to the throttle body first, then to the connection on the end tank. See Shoebox's online routing diagrams:

http://shbox.com/1/93-94_hoses.jpg

http://shbox.com/1/95-97_hoses.jpg

The radiator system can not bo "closed". The system needs some place for the coolant to escape from the system as it heats up and expands. The coolant expands until the pressure in the system hits 18psi, then the radiator cap spring opens and bleeds any excess coolant volume (due to thermal expansion) out of the system and into the overflow tank. When the coolant in the system cools down, is contracts, and causes a vacuum in the coolant system. The radiator cap moves in the oposite direction against the vacuum spring, and opens the passage from the overflow tank, sucking replacement coolant into the radiator, and eliminating the chances of vapor bubbles forming in the system.

You need the overflow tank.

Gearhead6s

So I need a recirculating overflow so that it can pull the coolant back into the radiator when it cools. How do I plumb that into my system when I only have the one connection at the radiator?

1racerdude

If ya are blowing the water out of the rad with the turbo and the rad is hooked up correct then your turbo is lifting the heads and presurizing the system. That is easy to do with the wrong gasket and fasteners and high boost.
Hook the hoses up correct and see if it still does it.
Ya could always put a unloader valve in the cooling system to relieve the pressure like the unloader in the turbo system.

Injuneer

If he's got the steam tube piping "tee'd" into the nipple for the overflow on the neck of the radiator, he's pumping coolant directly into the overflow. Somebody already pointed that out.

Is your Griffin radiator an LT1-specific model? I have a Griffin, and its got all the same connections as the stock radiator. Do you have a connection for the level sensor? Figure a way to pipe the steam pipe into that connection. The stock radiator is supposed to have a "vapor separator" inside the steam pipe connection. Not sure if the Griffin includes that.

96TurboTA

You have any pics of your turbo system?

1racerdude

Didn't catch the part that he has both connected together.
I might try reading a little better.

Gearhead6s

The car hasn't seen any boost yet only a 15min 2000rpm idle to break in the cam and get it up to The water coming out of the pipe is just what is always pumped there.
The radiator is not the LT1 specific it only has inlet, outlet and the filler neck nipple, thats all the ports that I have. I can't think of the part number right now, I have it at home, but its a common number used for the core support modification that allows the radiator to stand vertical. Guy that built my manifolds is a LS1 nut and thats the radiator they use most. Little did I think about the LT1 "steam" pipe. Could I just have someone weld a new nipple into the end tank under the neck nipple? Run the steam pipe to that?

1racerdude

A radiator shop can fix it just like your stock one.