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Bleeding the coolant system

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Old Jun 1, 2017 | 12:09 PM
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Default Bleeding the coolant system

So I'm pretty new to the whole car world and I'm trying to put coolant in my 96 Camaro SS Z28.

The ownder's manual (and everywhere on the internet) says to open the bleeder valves and put coolant in the radiator until a steady stream comes out of the bleed valves. When i try this, nothing comes out. The radiator gets completely filled and the valves help push more through the system but after some time, nothing else happens. The radiator stays topped off and the valves remain "dry". I know the valves themselves aren't clogged because coolant spurts out sometimes and if I squeeze some of the hoses, it comes out a bit.

I need to bleed my cooling system properly because I've been having coolant shooting out of the overflow cap for a while now and I think I narrowed it down to air in the lines.
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Old Jun 1, 2017 | 12:26 PM
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And I have 2 bleeder valves
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Old Jun 1, 2017 | 03:53 PM
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Which engine do you have?
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Old Jun 1, 2017 | 07:10 PM
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Originally Posted by G Atsma
Which engine do you have?
I think it's an LS1. It's a Z28 but Idk the difference between the LS1, LS2, LS3...
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Old Jun 1, 2017 | 07:27 PM
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When you say bleeder valves, I am curious what you mean. Can you post a picture(s)? I am new to the LSx and have not encountered any "bleeder" valve yet, so I am curious what they look like.

FWIW on my 5.3L (not the same engine, but like I said fwiw) to fill the system initially I vented the steam port lines (4-corner crossover) and used it like a siphon (applied a vacuum to the line, got the water flowing out of the heads and onto the ground through the hose) to drain from the top of the engine while filling from the radiator. This more or less suggests that the air is removed.
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Old Jun 1, 2017 | 07:31 PM
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Originally Posted by Josh Tuinder
I think it's an LS1. It's a Z28 but Idk the difference between the LS1, LS2, LS3...
Originally Posted by Josh Tuinder
So I'm pretty new to the whole car world and I'm trying to put coolant in my 96 Camaro SS Z28.

The ownder's manual (and everywhere on the internet) says to open the bleeder valves and put coolant in the radiator until a steady stream comes out of the bleed valves. When i try this, nothing comes out. The radiator gets completely filled and the valves help push more through the system but after some time, nothing else happens. The radiator stays topped off and the valves remain "dry". I know the valves themselves aren't clogged because coolant spurts out sometimes and if I squeeze some of the hoses, it comes out a bit.

I need to bleed my cooling system properly because I've been having coolant shooting out of the overflow cap for a while now and I think I narrowed it down to air in the lines.
A 1996 SS has a second gen 350 small block LT1 - unless it was LS swapped.
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Old Jun 1, 2017 | 07:48 PM
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Originally Posted by Darth_V8r
A 1996 SS has a second gen 350 small block LT1 - unless it was LS swapped.
Thank you
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Old Jun 1, 2017 | 08:05 PM
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No problem. Typically what works for me is to raise the font as high as possible. Start it and let it get good and hot. Then start squeezing hoses etc to get the air out.

Now, say you do all that and still getting it ... check compression. And do leak down test. Cracked heads and blown gaskets can leak compression into the cooling system.
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Old Jun 1, 2017 | 08:15 PM
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Originally Posted by Darth_V8r
No problem. Typically what works for me is to raise the font as high as possible. Start it and let it get good and hot. Then start squeezing hoses etc to get the air out.

Now, say you do all that and still getting it ... check compression. And do leak down test. Cracked heads and blown gaskets can leak compression into the cooling system.
I do have a warped head. I'm in the process of moving so I don't have the time to fix that/the money to have someone else do it.

So I should lift the front and fill it up the same way I am, then put the radiator cap back on, then start it to get it hot, then turn the car off, then squeeze hoses? I just want to make sure I'm not reading that the wrong way.
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Old Jun 5, 2017 | 05:12 PM
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You'd squeeze hoses etc while it's running. But with a warped head you could honestly have cylindervpressure leaking into cooling system. Bleed all you want that'll always put more air in
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Old Jun 6, 2017 | 08:02 PM
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Originally Posted by Josh Tuinder
I've been having coolant shooting out of the overflow cap for a while now...

I do have a warped head.
Originally Posted by Darth_V8r
...with a warped head you could honestly have cylindervpressure leaking into cooling system. Bleed all you want that'll always put more air in
That seems likely. By the way, coolant won't come out of the bleeder screws unless the engine is running or there is pressure in the system, such as when the car is still hot. You should bleed it with the engine running.
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Old Jun 6, 2017 | 08:43 PM
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Originally Posted by Darth_V8r
You'd squeeze hoses etc while it's running. But with a warped head you could honestly have cylindervpressure leaking into cooling system. Bleed all you want that'll always put more air in
So I lifted the front by driving up my driveway (very rough estimate of 25-30 degrees) and with the car off, coolant came out of one of the bleeder valves in a steady stream but the other one did the same thing it was doing before. If I run the car for a bit then turn it off, opening the one valve (that doesn't have anything flowing from it) puts more air into the system and raised the level in the radiator. It seems to do more bad than good having the valve open with the car running. It just lets a ton of air into the system.

Should I try to raise it up higher?

Do you think that the head would give enough presure into the cooling system to cause the overflow to spray like that? I'm going to see if my friend can help me get the head fixed. We can get it out then I can take it to a shop to get it machined.
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Old Jun 6, 2017 | 09:19 PM
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The bleeder screw should ideally be the high point in the system. If parking your car at an angle puts the radiator higher, than it can still have air trapped inside. My car is an LS1, so I do not have bleeder screws. I always bleed the air out at the radiator cap when parked facing uphill. Don't open the bleeder screws without the system pressurized, you'll just let more air in. I cannot think of a reason to open them with the car off.

Yes, a blown head gasket can easily cause the coolant to boil over.
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