bleeding air out of cooling system?
Thread Starter
Joined: Dec 2006
Posts: 848
Likes: 1
From: Crete, NE & Berthoud, CO
bleeding air out of cooling system? ok. does anyone know the right way to get all the air out of a ls1 cooling system? After i swapped my LS1 into my 69 Camaro it was getting hot (240). let it cool down and let it run with the cap off, and on, and off. finally the big pocket came out and the temp never went above 200. after the cam swap this weekend it wants to constantly run 230 with the factory thermostat. did the same things as before and cant get anymore air out. is there a bleed screw somewhere or some technique to getting the system right?? someone help so i can go have some fun!
TECH Apprentice
Joined: Jan 2005
Posts: 310
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If nobody else chimes in, I can look it up tonight, but from what I recall, all you have to do is let the motor rev (maybe at 3000 rpm) for 30 seconds, let it idle, top off the reservoir, rinse and repeat a few times.
Staging Lane
Joined: Jan 2007
Posts: 64
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there is a tool that you take off the cap, hook it onto your rad. and hook your shop air hose to it. then it has a tube that you put in your antifreeze/ water. theres a valve that you sut off to the water, then when youm you put air to it it creates a vacuam in the cooling system and then open the water valve and it sucks the water into your system. works really good, a friend of mine has one, i'm just not sure where he got it. maybe oreillys or autozone or something
Originally Posted by Schitzo
how did you fill in the coolant? I filled it in via the top hose slowly then topped the rad and also had the steam vent hooked up. Never went past 200.
Once the fluid starts spilling out of the top radiator hose connection, connect the hose to the radiator. Continue filling until the fluid starts to over flow the radiator cap opening. Close the cap & fill the overflow bottle about 1/2 way. Start the car & turn on the heater (high). Run for a couple of minutes & then shut off. Car shouldn't be hot enough to have built pressure. Overflow tank should be draining into the radiator. Once the overflow tank is empty, remove the cap & add fluid until full. Fill the overflow tank about 1/4 full & then start the car w/ heater on. Run car up to temp. & turn off. Overnight, the overflow may empty again if air remained. Fill the overflow tank as needed until it remains 1/4 to 1/2 full after cool down. You must connect the head vents to the radiator hose @ a high point or you'll always be fighting air pockets. Good-luck.
I'm running the steam vent hose to the top of the water pump on my '68, running a stock-ish '68 radiator, and filled the cooling system the same way as I did when it had a smallblock in it... fill it up to about 3/8 below the filler neck, push down on the upper radiator hose to burp it, and go back to fill and repeat until the level doesn't drop when I burp the upper hose. Mine runs 187F all day on the highway, and don't think I've seen it break 210F in traffic yet (Fan1 speed set to 206F, running stock '99 Fbody fans and stock-style dual-speed relay setup).
I've read about people using the steam vent line to top off the cooling system to avoid air pockets.
I've read about people using the steam vent line to top off the cooling system to avoid air pockets.
Thread Starter
Joined: Dec 2006
Posts: 848
Likes: 1
From: Crete, NE & Berthoud, CO
alright i will see what happens. I just filled through teh rad and not the top hose. I think i have most of it out as i took the cap off last night and the lever had gone gone about 3 inches. I didnt drive it yesterday so we will see what happens tonight. thanks for all the advice guy!
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Joined: Sep 2004
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From: Downers Grove, IL
I have filled it a few different ways.
1. Through the top hose (this method worked perfectly 3 of the 4 times I used it)
2. Forgot and filled it through the radiator = no dice, it shot up to 250 degrees and no matter what I did I could not get rid of the air pocket. I pulled the upper radiator hose filled it up and the temperature came down to 195-200 like normal.
3. The last time I filled it through the upper rad hose and it still had a huge air pocket with temps in the 240+ range, finally I opened the flush T in my heater hose, dumped about a gallon in and the air pocket was gone, the temps stabilized down around 200 within a minute of pouring the coolant into the heater hose.
1. Through the top hose (this method worked perfectly 3 of the 4 times I used it)
2. Forgot and filled it through the radiator = no dice, it shot up to 250 degrees and no matter what I did I could not get rid of the air pocket. I pulled the upper radiator hose filled it up and the temperature came down to 195-200 like normal.
3. The last time I filled it through the upper rad hose and it still had a huge air pocket with temps in the 240+ range, finally I opened the flush T in my heater hose, dumped about a gallon in and the air pocket was gone, the temps stabilized down around 200 within a minute of pouring the coolant into the heater hose.
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