LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

best way to refill coolant?

Old 02-20-2011, 02:31 PM
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best way to refill coolant?

Last fall I had my EWP go out and overheated my engine. Result was warped heads. It's all back together now and running but I need to fill the water and pressurize the system. What's the best way to do this? Turn the water pump on, make sure the resovoir is full, run the car, and continue to crack the bleed screw on the water neck? I've done this a few times in my life but it's been years and the only thing I remember for sure is that it was always a PITA. How do I know when it's ok? I've done a search but seem to get different opinions. I'm not really interested in purchasing any fancy tools or anything as I'd like to race next weekend if I can't get it full and bled out this week one evening. Thanks.
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Old 02-20-2011, 04:35 PM
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Re: best way to refill coolant?

http://shbox.com/1/4th_gen_tech2.html#radflush
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Old 02-20-2011, 06:57 PM
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Re: best way to refill coolant?

definitely follow shoebox's guidelines on his website, especially the part about removing the thermostat for refilling the engine/radiator with coolant. I've had great luck with it and have never had any problems getting all the air pockets out of the engine
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Old 02-20-2011, 09:37 PM
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Re: best way to refill coolant?

I fill mine with the air bleed screws open and basically have never had to worry about any air pockets.
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Old 02-20-2011, 11:38 PM
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Re: best way to refill coolant?

I followed shoebox's guide and it worked great for me.
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Old 02-21-2011, 07:31 AM
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Re: best way to refill coolant?

Two dumb questions. First, where is the 2nd air bleed screw? I know about the one on the thermostat housing. Next, the article talks about filling the radiator neck. There is no radiator cap on the Impala to fill IIRC. The only place to add water is at the reservoir unless I didn't look closely enough. I feel stupid as I've successfully removed the heads, had them fixed, put them back on, adjusted valves, etc. and now I am having trouble getting water in the thing.
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Old 02-21-2011, 07:48 AM
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Re: best way to refill coolant?

Originally Posted by Tar Heel
Two dumb questions. First, where is the 2nd air bleed screw? I know about the one on the thermostat housing. Next, the article talks about filling the radiator neck. There is no radiator cap on the Impala to fill IIRC. The only place to add water is at the reservoir unless I didn't look closely enough. I feel stupid as I've successfully removed the heads, had them fixed, put them back on, adjusted valves, etc. and now I am having trouble getting water in the thing.
Ok, I figured out that the 2nd bleed screw was part of the AC system which of course I don't have anymore. I didn't think I was losing my mind. I'll have to go home tonight and look at it but I thought my radiator didn't have a place to add water as described in the article.

BTW shoebox, you have no idea how valuable your tech articles are!!! They are greatly appreciated. I'm a school teacher, coach, and not a mechanic by any means so I don't do these things enough to remember them. It is SO nice to have something to refer back to when I'm piddling in the garage on the weekends. I can't tell you how many times I've printed off your pages and referred to them. Thank you.
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Old 02-21-2011, 08:29 AM
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Re: best way to refill coolant?

Originally Posted by shoebox
With the engine running, add coolant to the radiator until the level is as high as you can get it. This may be tricky if you have an electric pump because coolant may try to gush out-be careful. Install cap sooner if coolant gushes out.

I have never been able to get a definitive answer on this. What do we mean by "gushing out"?

I ask, because when I try to run my car without the radiator cap, after a while, water (very hot water) explodes out of the radiator opening. Is this normal? Did I wait too long?

I'm using the stock mechanically driven pump, not an electric one.

After filling the radiator, putting the cap on, bleeding several times, the car will run fine. The low coolant light never goes out & I maintain a level in the overflow bottle.

Every now and then, after driving on a very hot day, when I park the car water leaks to the ground from the overflow bottle. If I fill it to it's proper level before starting the car, everything is fine. But if I don't, the car does overheat.

Now, when I talk to other people, they tell me I've got a blown head gasket. But I never see water anywhere it isn't supposed to be, and like I said, the car runs pretty good.
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Old 02-21-2011, 09:41 AM
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Re: best way to refill coolant?

The LT1 cooling system is different on each body - F-Body, Y-Body and B-Body. The Y-Body for example is "self bleeding". If GM hadn't gotten cheap, and eliminated that valuable feature on the other LT1 applications, there would have been a lot less problems with the cooling system. You need an instruction specifically for the B-Body. Or you need our resident B-Body expert, Dwayne ("96capricemgr") to help you out.

Not sure why they would incorporate a coolant system air vent into the A/C components, since there is no coolant supplied to that system.
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Old 02-21-2011, 10:04 AM
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Re: best way to refill coolant?

Originally Posted by Injuneer
The LT1 cooling system is different on each body - F-Body, Y-Body and B-Body. The Y-Body for example is "self bleeding". If GM hadn't gotten cheap, and eliminated that valuable feature on the other LT1 applications, there would have been a lot less problems with the cooling system. You need an instruction specifically for the B-Body. Or you need our resident B-Body expert, Dwayne ("96capricemgr") to help you out.

Not sure why they would incorporate a coolant system air vent into the A/C components, since there is no coolant supplied to that system.
From the picture linked off shoebox's instruction sheet the other bleeder screw is something that I don't have because my AC system has been removed. I don't know why it would be part of that system but I'm sure I don't have the 2nd one based on his picture.

Also, I'll have to look at it tonight but I'm sure also that we don't have a radiator cap and way to fill coolant on the Impalas at the radiator. The pressurized cap is on the reservoir tank located on the passenger's side inner fender. I'm thinking that maybe I would fill that reservoir tank and bleed the system from the one bleeder screw I have on the thermostat housing.
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Old 02-21-2011, 10:44 AM
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Re: best way to refill coolant?

Originally Posted by TUNDRKYS
I have never been able to get a definitive answer on this. What do we mean by "gushing out"?

I ask, because when I try to run my car without the radiator cap, after a while, water (very hot water) explodes out of the radiator opening. Is this normal? Did I wait too long?

I'm using the stock mechanically driven pump, not an electric one.

After filling the radiator, putting the cap on, bleeding several times, the car will run fine. The low coolant light never goes out & I maintain a level in the overflow bottle.

Every now and then, after driving on a very hot day, when I park the car water leaks to the ground from the overflow bottle. If I fill it to it's proper level before starting the car, everything is fine. But if I don't, the car does overheat.

Now, when I talk to other people, they tell me I've got a blown head gasket. But I never see water anywhere it isn't supposed to be, and like I said, the car runs pretty good.
Gushing out is just like you said and yes, you waited too long. After the thermostat opens, water will quickly want to come out of the filler neck. You'll have to be attentive and get the cap back on sooner.

Like I said above, I get most of the air purged by keeping the bleeders open during filling. I'll burp the bleeders again when the system is closed, just to see if any air comes out. It is usually minimal. After cool-down, I'll take off the cap and verify the radiator level and top-off, if needed.
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Old 02-21-2011, 10:53 AM
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Re: best way to refill coolant?

Originally Posted by Tar Heel
Ok, I figured out that the 2nd bleed screw was part of the AC system which of course I don't have anymore. I didn't think I was losing my mind. I'll have to go home tonight and look at it but I thought my radiator didn't have a place to add water as described in the article.

BTW shoebox, you have no idea how valuable your tech articles are!!! They are greatly appreciated. I'm a school teacher, coach, and not a mechanic by any means so I don't do these things enough to remember them. It is SO nice to have something to refer back to when I'm piddling in the garage on the weekends. I can't tell you how many times I've printed off your pages and referred to them. Thank you.
Yeah, the article is for an f-body and any differences with the b-body will need to be accounted for. I just looked up a drawing of the b-body system and it does not have a radiator cap, but uses a pressurized remote filler.

I appreciate the website thanks.
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Old 02-21-2011, 11:13 AM
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Re: best way to refill coolant?

I think I'm on the right track with what I'm doing but will try it again with the heater on to purge air from there as well. I'll get to the bottom of this mystery by golly ...
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Old 02-21-2011, 12:12 PM
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Re: best way to refill coolant?

Did you put the coolant crossover back on the rear of the heads? Just a dumb thought, but I know if this is removed it will cause nightmares.
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Old 02-21-2011, 12:33 PM
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Re: best way to refill coolant?

Originally Posted by 97FormulaWS-6
Did you put the coolant crossover back on the rear of the heads? Just a dumb thought, but I know if this is removed it will cause nightmares.
Yes, I NEVER cuss but that was reason to. Lots of fun doing it with the engine in the car ... I swear you have to lay on the engine to get back there to do it. Getting too old for that ...
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