Burping Radiator--What did I do wrong???
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Joined: Sep 2002
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From: Buford Georgia
Burping Radiator--What did I do wrong???
1989 L98 auto.
Followed the steps below. Only difference is the engine was already warm (180 degrees). After turning the engine on I added a little more coolant and saw the level raising and lowering. My wife brought the engine up to around 1500 rpm's, I filled the rest of the way but before I could put the cap back on it started spewing hot coolant out the the radiator like a fountain.
Where did I mess up or do I have another problem?
Steps:
1. Add a mixture of one-half water and one-half antifreeze to the radiator. Fill it right up to the top.
2. Fill the overflow/coolant reservoir with the same 50/50 mixture.
3. Leave the radiator cap off, turn the engine on and let it run until the radiator "burps": You will see the coolant level drop and may see or hear a large air bubble come to the top as the system burps.
4. Keep an eye on the temperature gauge throughout this process.
5. Refill the radiator to the top and coolant reservoir as needed.
6. Put the radiator cap back on.
7. Note that if the engine runs hot after this procedure there may have been another pocket of air that "burped." Let the engine cool down and then add more coolant to both the radiator and the coolant reservoir.
Followed the steps below. Only difference is the engine was already warm (180 degrees). After turning the engine on I added a little more coolant and saw the level raising and lowering. My wife brought the engine up to around 1500 rpm's, I filled the rest of the way but before I could put the cap back on it started spewing hot coolant out the the radiator like a fountain.
Where did I mess up or do I have another problem?
Steps:
1. Add a mixture of one-half water and one-half antifreeze to the radiator. Fill it right up to the top.
2. Fill the overflow/coolant reservoir with the same 50/50 mixture.
3. Leave the radiator cap off, turn the engine on and let it run until the radiator "burps": You will see the coolant level drop and may see or hear a large air bubble come to the top as the system burps.
4. Keep an eye on the temperature gauge throughout this process.
5. Refill the radiator to the top and coolant reservoir as needed.
6. Put the radiator cap back on.
7. Note that if the engine runs hot after this procedure there may have been another pocket of air that "burped." Let the engine cool down and then add more coolant to both the radiator and the coolant reservoir.
Race Director
Joined: Aug 2000
Posts: 11,506
Likes: 4
From: Vancouver,Wa.
Sounds like you had a air pocket in the intake. The thermostat had no water contact on it causing it not to open at it's proper temp. By the time it did open the pressure was there. I like to drill a couple small hole in my thermostat to prevent this.
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
It's easy to get bubbles trapped in the engine, that's actually what that silly hose is for in the back of the engine. What you've done is pretty normal if you leave the cap off, remember this is a PRESSURE system. I usually fill the system, cap on tight, run it awhile, even drive it, let it cool, check and add fluid. Check a couple of times over the next few days. If you keep losing flluid after that, well, that's a different thread.
Oh, I'd probably change the radiator cap.
Oh, I'd probably change the radiator cap.
Last edited by zr1fred; Aug 9, 2006 at 10:37 AM.
Thread Starter
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Joined: Sep 2002
Posts: 609
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From: Buford Georgia
thanks. I'm pulling the thermostat out tonight to put a couple of holes in it. Seems to be running Ok after I refilled it last night but wanted to make sure I was not missing something.
Something so simple should not be such a pain....
Something so simple should not be such a pain....
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Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by C4Me
Steps:
1. Add a mixture of one-half water and one-half antifreeze to the radiator. Fill it right up to the top. Check.
2. Fill the overflow/coolant reservoir with the same 50/50 mixture. Only to the level marked, "Hot".
3. Leave the radiator cap off, turn the engine on and let it run until the radiator "burps": You will see the coolant level drop and may see or hear a large air bubble come to the top as the system burps. Keep feeling the upper radiator hose for signs the thermostat has opened (the hose gets hot) and keep checking the water in the radiator to watch for the water to start flowing or the level dropping. These aren't subtle changes. When the water level drops it drops a bunch, or when the water starts moving, it MOVES. At THIS time rev the engine to 2500 - 3000 rpms and add water. As soon as it has been filled, put the cap on. AFTER the cap is secure, you can reduce the engine speed.
4. Keep an eye on the temperature gauge throughout this process. Never a bad idea, but once the thermostat opens, things go pretty fast, and there is little time for gauge checking, or for overheating.
5. Refill the radiator to the top and coolant reservoir as needed. No. Don't remove the radiator cap at this point. Leave the reservoir alone also. The level shouldn't have moved much, if any, since you filled it to the "Hot" level.
6. Put the radiator cap back on. Skip, because you shouldn't have removed it.
7. Note that if the engine runs hot after this procedure there may have been another pocket of air that "burped." Let the engine cool down and then add more coolant to both the radiator and the coolant reservoir. After stop 6. it is fine to drive the car, but certainly not necessary. After the engine has thoroughly cooled, remove the radiator cap and add water to overflowing, if there is room. Also check the reservoir to be sure the water level is at "Cold" or slightly higher, is OK. One or two more cold checks after the engine has been warmed up, won't hurt.
1. Add a mixture of one-half water and one-half antifreeze to the radiator. Fill it right up to the top. Check.
2. Fill the overflow/coolant reservoir with the same 50/50 mixture. Only to the level marked, "Hot".
3. Leave the radiator cap off, turn the engine on and let it run until the radiator "burps": You will see the coolant level drop and may see or hear a large air bubble come to the top as the system burps. Keep feeling the upper radiator hose for signs the thermostat has opened (the hose gets hot) and keep checking the water in the radiator to watch for the water to start flowing or the level dropping. These aren't subtle changes. When the water level drops it drops a bunch, or when the water starts moving, it MOVES. At THIS time rev the engine to 2500 - 3000 rpms and add water. As soon as it has been filled, put the cap on. AFTER the cap is secure, you can reduce the engine speed.
4. Keep an eye on the temperature gauge throughout this process. Never a bad idea, but once the thermostat opens, things go pretty fast, and there is little time for gauge checking, or for overheating.
5. Refill the radiator to the top and coolant reservoir as needed. No. Don't remove the radiator cap at this point. Leave the reservoir alone also. The level shouldn't have moved much, if any, since you filled it to the "Hot" level.
6. Put the radiator cap back on. Skip, because you shouldn't have removed it.
7. Note that if the engine runs hot after this procedure there may have been another pocket of air that "burped." Let the engine cool down and then add more coolant to both the radiator and the coolant reservoir. After stop 6. it is fine to drive the car, but certainly not necessary. After the engine has thoroughly cooled, remove the radiator cap and add water to overflowing, if there is room. Also check the reservoir to be sure the water level is at "Cold" or slightly higher, is OK. One or two more cold checks after the engine has been warmed up, won't hurt.
RACE ON!!!
Last edited by CFI-EFI; Aug 9, 2006 at 11:44 AM.
Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
Originally Posted by CFI-EFI
All of this is slightly easier if the front wheels of the car is on ramps, at the time. The reason for all the trouble (burping) is that the radiator cap isn't the high point of the cooling system. The ramps can help a little.
RACE ON!!!
RACE ON!!!
Thread Starter
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Joined: Sep 2002
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From: Buford Georgia
Originally Posted by CFI-EFI
All of this is slightly easier if the front wheels of the car is on ramps, at the time. The reason for all the trouble (burping) is that the radiator cap isn't the high point of the cooling system. The ramps can help a little.
RACE ON!!!
RACE ON!!!
I think part of my problem was removing the cap again before it cooled down. Ran ok into work today. I will let it cool off and check it again tonight.
Thanks for the tips.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by C4Me
I never thought about the ramps.
I think part of my problem was removing the cap again before it cooled down.
I think part of my problem was removing the cap again before it cooled down.
Originally Posted by Dominic Sorresso
I put a back flush valve on the rear intake hose and fill the system from there. Since that is typically the highest point, air will bleed out as fluid goes in.
RACE ON!!!
Melting Slicks
Joined: Apr 2002
Posts: 2,118
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From: St. Charles, MO Route 66 Corvette Club
I drill two 1/8" holes in the BODY of the theremostat and do not have to deal with trapped air. I start the engine, drink a Bud Lite and add coolant as needed. Done deal 
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Just don't drill too many holes and too big. Doing so will extend your warm up period during start up. It will help with burping air, but will extend your warm up periods at cold start up in direct relation to the size of the drilled areas if overdone.
There's been disagreement in regards to the practicality of drilling holes in the thermostat.
Drilling holes serves to make the car take longer to get to the same temps. It won't keep it from overheating if it already is. You just won't have to sweat it as much now when you are stopped at a light, because the holes provide a small constant flow of coolant circulation, making the car take longer to get to the same temperatures, reducing temperature spikes. It will still get up there in temps, just takes longer with holes.
Better than just drilling holes is to establish a properly maintined cooling system, and turn your fans on earlier than stock by either a custom chip or a low temp fan switch.
There's been disagreement in regards to the practicality of drilling holes in the thermostat.
Drilling holes serves to make the car take longer to get to the same temps. It won't keep it from overheating if it already is. You just won't have to sweat it as much now when you are stopped at a light, because the holes provide a small constant flow of coolant circulation, making the car take longer to get to the same temperatures, reducing temperature spikes. It will still get up there in temps, just takes longer with holes.
Better than just drilling holes is to establish a properly maintined cooling system, and turn your fans on earlier than stock by either a custom chip or a low temp fan switch.
Thread Starter
Pro
Joined: Sep 2002
Posts: 609
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From: Buford Georgia
I was thinking of the holes to help burp the air out of the system easily. Not as much in the cooling aspect. Since replacing the coolant and putting in a new thermostat it seems to be running cooler.
Checked the level this morning while it was still cold and added some coolant. So far it seems to be running around 189 driving on the highway and 205 to 225 in stop and go traffic. The weather has been hot and humid. Fan seems to kick on at 225 and off at around 210. I can live with that for now. May work on changing the fan on and off settings later.
Thanks for everyone's help.
Checked the level this morning while it was still cold and added some coolant. So far it seems to be running around 189 driving on the highway and 205 to 225 in stop and go traffic. The weather has been hot and humid. Fan seems to kick on at 225 and off at around 210. I can live with that for now. May work on changing the fan on and off settings later.
Thanks for everyone's help.
Thread Starter
Pro
Joined: Sep 2002
Posts: 609
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From: Buford Georgia
Originally Posted by Sam Lam
I drill two 1/8" holes in the BODY of the theremostat and do not have to deal with trapped air. I start the engine, drink a Bud Lite and add coolant as needed. Done deal
Racer
Joined: May 2006
Posts: 286
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From: Alpine California
Originally Posted by C4Me
I was thinking of the holes to help burp the air out of the system easily. Not as much in the cooling aspect. Since replacing the coolant and putting in a new thermostat it seems to be running cooler.
86Pacer, I agree with everything you said, I just don't think you understood the point of the holes. This is to allow trapped air to escape from under the thermostat up into the radiator when filling, not to help with any cooling issues. For this purpose, it's a great mod.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Originally Posted by Blownfuel1
86Pacer, I agree with everything you said, I just don't think you understood the point of the holes. This is to allow trapped air to escape from under the thermostat up into the radiator when filling, not to help with any cooling issues. For this purpose, it's a great mod.Last edited by 86PACER; Aug 10, 2006 at 07:53 PM.
