Radiator purge questions?
Thread Starter
TECH Apprentice
Joined: Jun 2002
Posts: 319
Likes: 0
From: NH
Radiator purge questions? I got the car running and let it reach temperature. Once the thermostat opened the system started puking from the bleed hole in my overflow tank (Jaz bottle). I expected this because I teed into the overflow line coming from the filler neck on my radiator. What is a way (not necessarily the best way) to set this up. I am trying to avoid emptying and modifying my radiator. Can I run the throttle body bypass line back into the upper radiator hose someway? Will the bleed hole in my overflow tank have to be the highest point in the system? Can I just cap off the throttle body line? Looking at my 2001 Silverado for reference, it appears that this throttle body line comes into the radiator at a lower point than the overlow line. Also, the overflow tank is sitting midway up the front fender much higher than the radiator. Please help with suggestions. If I have to modify the radiator can I tap the radiator tank or do I have to braze on a fitting. If brazing, how to I do that? Do they sell fittings for this? I have solder and map gas. 
Re: Radiator purge questions? You can't bleed into the overflow line.
What you could do, I think, Is get some sort of bleeder valve and cap off the line that should go to the radiator from the tb or front coolant rail. Then manually bleed the system.
Or just use a stock LS1 radiator that has the provision for that coolant line BELOW the overflow tank line.
What you could do, I think, Is get some sort of bleeder valve and cap off the line that should go to the radiator from the tb or front coolant rail. Then manually bleed the system.
Or just use a stock LS1 radiator that has the provision for that coolant line BELOW the overflow tank line.
Staging Lane
Joined: Jan 2003
Posts: 53
Likes: 0
From: roanoke, va.
Re: Radiator purge questions? I got a 1/4 pipe by 5/16 hose barb brass fitting, drilled my radiator under pressure cap (drilling up to keep shavings out of radiator) and soldered in the fitting. The only problem I had was I had take off the top radiator hose and fill the motor with water after I had filled the radiator. I bought a overflow tank from advance auto parts for $6.99 and mounted it about halfway down the side of my radiator with the bracket bolted to the battery tray. The original overflow tank position on my 79 elcamino was taken up by the pcm. Started engine last week and everything works perfect. I have the overflow tank on my EFI 406 67 nova mounted under the battery tray which puts it at the bottom of the radiator and it works fine. 
Staging Lane
Joined: Jan 2003
Posts: 53
Likes: 0
From: roanoke, va.
Re: Radiator purge questions? I am using the stock radiator out of my 79 elcamino. The top radiator hose goes in on the driver's side, and the pressure cap is on the passenger's. I used a unibit which is perfect for drilling thin metal such as a radiator's side tanks. I drilled about halfway between the pressure cap and the core. After I done this and first started the motor, after it warmed up the thing sprung a leak. I guess 24 years old I should expect things like this. I bought a new one for $87 at an advance auto and it already had a fitting at the exact same place, all I had to do was reduce the threads from 1/2 pipe to 1/4 pipe and screw in my 1/4 pipe to 5/16th hose barb. Works perfect.
