Low Coolant Light&Low coolant
11-30-2013, 01:15 PM
#1
Drifting
Thread Starter
Low Coolant Light&Low coolant
Had my radiator flushed several months ago and I think there may still be some air in the system?
The low coolant light has come on twice now and the radiator was a little low, so I topped it off and everything was fine for a month and now it did the same thing?
The car runs cool and never gets too hot. I've checked the oil and there is no coolant visible and there are no antifreeze leaks anywhere.
Searched the forums on how to easily burp the system. Tell me if this willl work.
With the engine cold, remove the radiator cap and start the engine, let it run for a few minutes till the T-Stat opens, then have someone raise the rpm's to about 2,000-2200 for about a minute or so, while you top off the radiator while watching for air bubbles.
Any comments or suggestions would be appreciated!
The low coolant light has come on twice now and the radiator was a little low, so I topped it off and everything was fine for a month and now it did the same thing?
The car runs cool and never gets too hot. I've checked the oil and there is no coolant visible and there are no antifreeze leaks anywhere.
Searched the forums on how to easily burp the system. Tell me if this willl work.
With the engine cold, remove the radiator cap and start the engine, let it run for a few minutes till the T-Stat opens, then have someone raise the rpm's to about 2,000-2200 for about a minute or so, while you top off the radiator while watching for air bubbles.
Any comments or suggestions would be appreciated!
11-30-2013, 01:27 PM
#2
I also recommend that you bleed the cooling system with the bleed screw located on the t-stat outlet from the water pump. Did you ensure that the proper coolant was added? Depending on what engine you have, all LT1s require DEX-COOL extended life coolant (orange in color). If regular standard green coolant was added it will royally turn your coolant into a sludge over time! The two coolants are NOT compatible and will require a full cooling system flush to removal the sludge. Also check your T-stat and ensure it is opening and closing at the proper temps. And lastly, check your water pump and ensure it is pumping at full volume by running the engine until the t-stat opens and squeeze the upper and lower radiator hoses to feel for any pressure. Good luck.
11-30-2013, 01:55 PM
#3
Team Owner
I also recommend that you bleed the cooling system with the bleed screw located on the t-stat outlet from the water pump. Did you ensure that the proper coolant was added? Depending on what engine you have, all LT1s require DEX-COOL extended life coolant (orange in color). If regular standard green coolant was added it will royally turn your coolant into a sludge over time! The two coolants are NOT compatible and will require a full cooling system flush to removal the sludge. Also check your T-stat and ensure it is opening and closing at the proper temps. And lastly, check your water pump and ensure it is pumping at full volume by running the engine until the t-stat opens and squeeze the upper and lower radiator hoses to feel for any pressure. Good luck.
As far as Dexcool being standard, that didn't start until the 1996 model year. All C4's prior to that used the green ethlyene glycol coolant.
Dexcool can be used in earlier cars but it's very important that the cooling system is flushed so that there are no traces left of the green coolant.
What the OP can do to get rid of any air pockets is to raise the front of the car as high as possible. Start the engine and with the pressure cap off, let the coolant temp come up to where the t-stat is fully open. Run the engine at something like 1100 to 1200 RPM and start adding coolant until the level is at the top. Replace the cap, lower the idle and then get the car back on the ground.
Remove the plastic overflow container and empty it. Clean the inside as necessary and replace it. With the engine cool, add a 50% coolant mix to the COLD line.
11-30-2013, 05:59 PM
#4
It looks like the OP has an L98 (1990 car) so he may not have a bleed screw in either the t-stat housing or the TB.
As far as Dexcool being standard, that didn't start until the 1996 model year. All C4's prior to that used the green ethlyene glycol coolant.
Dexcool can be used in earlier cars but it's very important that the cooling system is flushed so that there are no traces left of the green coolant.
What the OP can do to get rid of any air pockets is to raise the front of the car as high as possible. Start the engine and with the pressure cap off, let the coolant temp come up to where the t-stat is fully open. Run the engine at something like 1100 to 1200 RPM and start adding coolant until the level is at the top. Replace the cap, lower the idle and then get the car back on the ground.
Remove the plastic overflow container and empty it. Clean the inside as necessary and replace it. With the engine cool, add a 50% coolant mix to the COLD line.
As far as Dexcool being standard, that didn't start until the 1996 model year. All C4's prior to that used the green ethlyene glycol coolant.
Dexcool can be used in earlier cars but it's very important that the cooling system is flushed so that there are no traces left of the green coolant.
What the OP can do to get rid of any air pockets is to raise the front of the car as high as possible. Start the engine and with the pressure cap off, let the coolant temp come up to where the t-stat is fully open. Run the engine at something like 1100 to 1200 RPM and start adding coolant until the level is at the top. Replace the cap, lower the idle and then get the car back on the ground.
Remove the plastic overflow container and empty it. Clean the inside as necessary and replace it. With the engine cool, add a 50% coolant mix to the COLD line.
11-30-2013, 06:40 PM
#5
Melting Slicks
if you have air pockets after your car has ran more then a half hour and not over heated you dont have air pockets. once you have been running the car and shut it off cooleant will flow into the recovery tank once started again it will draw the colleant back out of the tank this will eleminate all traped air. now if you are getting air into the system it is coming from a blown head gasket
Last edited by hooked073; 11-30-2013 at 06:46 PM.
11-30-2013, 06:55 PM
#6
Melting Slicks
with over 33 yrs incharge of a large fllet. I have never seen or head of a reason to jack a car up to top the colleant leavel. The fill point on just about every vehicle is above the top of the engine so I dont see how anything is gained? Also all reveing an engine does is draw more cooleant into the engine then it needs as soon as you replace the cap and top off the recovery take you recovery tank is going to be over full and push excess out all over the place
11-30-2013, 08:01 PM
#7
Team Owner
with over 33 yrs incharge of a large fllet. I have never seen or head of a reason to jack a car up to top the colleant leavel. The fill point on just about every vehicle is above the top of the engine so I dont see how anything is gained? Also all reveing an engine does is draw more cooleant into the engine then it needs as soon as you replace the cap and top off the recovery take you recovery tank is going to be over full and push excess out all over the place
The purpose of slightly raising the engine RPM is to try to force the air pocket thru the block and hoses so that the air can escape thru the open filler hole.
Even the later C4's that use an expansion tank above the engine can have air pockets formed during a fill. The FSM for LT1 cars even state that raising engine RPM somewhat will cause air pockets to come up into the expansion tank so that you can completely fill the system.
The plastic overflow tank for C4's located in the RF headlamp well holds a good 1/2 gallon if not a full gallon. If you look at the COLD line on these tanks, it's very low. The amount of coolant in the tank when filled to the COLD line is no more than a quart. That leaves a lot of room for hot coolant under pressure to move into that tank. As the engine cools, that coolant is sucked back into the radiator.
11-30-2013, 08:10 PM
#8
Melting Slicks
Refilling coolant in L98 Corvettes can easily result in air pockets being formed. It's been discussed here for years and the best way to remove the air pockets is to raise the top of the filler opening above the highest point of the engine. Remembers that stock L98's have a coolant line that run thru the bottom of the throttle body. Air can get trapped there.
The purpose of slightly raising the engine RPM is to try to force the air pocket thru the block and hoses so that the air can escape thru the open filler hole.
Even the later C4's that use an expansion tank above the engine can have air pockets formed during a fill. The FSM for LT1 cars even state that raising engine RPM somewhat will cause air pockets to come up into the expansion tank so that you can completely fill the system.
The plastic overflow tank for C4's located in the RF headlamp well holds a good 1/2 gallon if not a full gallon. If you look at the COLD line on these tanks, it's very low. The amount of coolant in the tank when filled to the COLD line is no more than a quart. That leaves a lot of room for hot coolant under pressure to move into that tank. As the engine cools, that coolant is sucked back into the radiator.
The purpose of slightly raising the engine RPM is to try to force the air pocket thru the block and hoses so that the air can escape thru the open filler hole.
Even the later C4's that use an expansion tank above the engine can have air pockets formed during a fill. The FSM for LT1 cars even state that raising engine RPM somewhat will cause air pockets to come up into the expansion tank so that you can completely fill the system.
The plastic overflow tank for C4's located in the RF headlamp well holds a good 1/2 gallon if not a full gallon. If you look at the COLD line on these tanks, it's very low. The amount of coolant in the tank when filled to the COLD line is no more than a quart. That leaves a lot of room for hot coolant under pressure to move into that tank. As the engine cools, that coolant is sucked back into the radiator.
12-01-2013, 02:35 AM
#9
There is a reason the late L98 's and LT1's have a remote header tank mounted high above the engine
There is a noticeable drop in the radiator level with the RPM raised;
once the extra coolant is added and the cap is replaced, no coolant comes out except from normal expansion into the overflow tank which is sucked back in when the engine cools off
Been using the suggested fill method for 15 years and the tank level never varies when the engine cools off
Don't know about your '87 but on mine the thermo housing outlet and top radiator hose are higher than the radiator shroud , let alone the filler cap.
Last edited by vetteoz; 12-01-2013 at 02:39 AM.
12-01-2013, 09:03 AM
#11
Drifting
Thread Starter
Found this on the Interweb, think I'll try this method and let you guy's know how it worked. Thanks for all the advice!
Proper Radiator Burping Procedure for the L98 Cooling System.
Remove the radiator cap and fill the radiator all the way to the top with coolant.
Fill the overflow tank to the cold fill mark.
Start your Corvette and let it idle.
Periodically squeeze the upper radiator hose to test it's heat level.
Once the hose becomes warm and you can feel coolant circulate throuhg the hose, your thermostat is open.
Next have someone raise the rpm's to approximately 2200 and hold it there.
The coolant level in the radiator will drop.
Fill with coolant all the way to the top, while continuing to maintain the rpm's at 2200.
Continue to hold the rpm's at 2200 for approximately 30 to 45 seconds while the air bubbles are allowed to escape the system.
Continue to add coolant needed to top off the system.
Replace the radiator cap before letting the engine return to idle.
Your L98 cooling system is now properly configured.
Proper Radiator Burping Procedure for the L98 Cooling System.
Remove the radiator cap and fill the radiator all the way to the top with coolant.
Fill the overflow tank to the cold fill mark.
Start your Corvette and let it idle.
Periodically squeeze the upper radiator hose to test it's heat level.
Once the hose becomes warm and you can feel coolant circulate throuhg the hose, your thermostat is open.
Next have someone raise the rpm's to approximately 2200 and hold it there.
The coolant level in the radiator will drop.
Fill with coolant all the way to the top, while continuing to maintain the rpm's at 2200.
Continue to hold the rpm's at 2200 for approximately 30 to 45 seconds while the air bubbles are allowed to escape the system.
Continue to add coolant needed to top off the system.
Replace the radiator cap before letting the engine return to idle.
Your L98 cooling system is now properly configured.
12-01-2013, 11:28 AM
#12
Melting Slicks
Found this on the Interweb, think I'll try this method and let you guy's know how it worked. Thanks for all the advice!
Proper Radiator Burping Procedure for the L98 Cooling System.
Remove the radiator cap and fill the radiator all the way to the top with coolant.
Fill the overflow tank to the cold fill mark.
Start your Corvette and let it idle.
Periodically squeeze the upper radiator hose to test it's heat level.
Once the hose becomes warm and you can feel coolant circulate throuhg the hose, your thermostat is open.
Next have someone raise the rpm's to approximately 2200 and hold it there.
The coolant level in the radiator will drop.
Fill with coolant all the way to the top, while continuing to maintain the rpm's at 2200.
Continue to hold the rpm's at 2200 for approximately 30 to 45 seconds while the air bubbles are allowed to escape the system.
Continue to add coolant needed to top off the system.
Replace the radiator cap before letting the engine return to idle.
Your L98 cooling system is now properly configured.
Proper Radiator Burping Procedure for the L98 Cooling System.
Remove the radiator cap and fill the radiator all the way to the top with coolant.
Fill the overflow tank to the cold fill mark.
Start your Corvette and let it idle.
Periodically squeeze the upper radiator hose to test it's heat level.
Once the hose becomes warm and you can feel coolant circulate throuhg the hose, your thermostat is open.
Next have someone raise the rpm's to approximately 2200 and hold it there.
The coolant level in the radiator will drop.
Fill with coolant all the way to the top, while continuing to maintain the rpm's at 2200.
Continue to hold the rpm's at 2200 for approximately 30 to 45 seconds while the air bubbles are allowed to escape the system.
Continue to add coolant needed to top off the system.
Replace the radiator cap before letting the engine return to idle.
Your L98 cooling system is now properly configured.
12-01-2013, 11:44 AM
#15
Melting Slicks
I widh a lot of people would find a book on the basic of cooling systems. one of the designs that was incorperrated into the vented cap was a way to release common air traped into the system this has been in effect sense the advent of the closed system. everytime time the car is shut off pressure builds in the system when the pressure reaches a certain pressure point the cap will open releaving excess pressure and air in the system. that was half of the design of the cap
12-01-2013, 12:04 PM
#17
Safety Car
Originally Posted by AirForceOne!
The low coolant light has come on twice now and the radiator was a little low, so I topped it off and everything was fine for a month and now it did the same thing?
The car runs cool and never gets too hot. I've checked the oil and there is no coolant visible and there are no antifreeze leaks anywhere.
Simply, with a full radiator & block, plus the coolant level at the 'cold' mark on the overflow bottle, coolant will expand into the overflow bottle after reaching op temp....... then siphon back into the radiator during cool-down..... repeatedly.
If the coolant level in the overflow bottle is elevated after running at temp, but does not recede after cool-down, then the siphon is not occurring due to: rad cap gasket split/deformed, air is entering the system via loose hose ends, split hose ends, any condition that is allowing air to enter the cooling system.
Without a return siphon, coolant is only flowing out, creating a low-coolant condition.
Check the overflow bottle when hot, and then when cold. There should be a difference in coolant level. How old is the rad cap?
If air is continually bubbling out, it is possible to have a ruptured head gasket allowing exhaust gases into the cooling system. But, normally, if so, you would witness high op temps, and coolant being forced out under high pressure.
Last edited by don hall; 12-01-2013 at 12:08 PM.
12-01-2013, 12:11 PM
#18
Melting Slicks
for anyone who suspects head gasket leaks of compression getting into the cooling system. Rent or by a cooleaant pressure tester. Start your car get it up to temp. shut it off carefully releave pressure and remove the cap. Install the pressure tester do not pump it up. Start the car hold at about 2500 rmp if the gauge starts building pressure fast you know you have compression intering the system
12-01-2013, 12:13 PM
#19
Drifting
Thread Starter
Just replaced the radiator cap a few weeks ago.
I have never checked the overflow hot, just cold and it is always at the cold level. I'll check it hot next time I drive it, which looks like next week, we have a big storm headed our way!
I have never checked the overflow hot, just cold and it is always at the cold level. I'll check it hot next time I drive it, which looks like next week, we have a big storm headed our way!
12-01-2013, 12:13 PM
#20
Melting Slicks
You haven't commented on the basic function of the 'closed cooling system' for your vette.
Simply, with a full radiator & block, plus the coolant level at the 'cold' mark on the overflow bottle, coolant will expand into the overflow bottle after reaching op temp....... then siphon back into the radiator during cool-down..... repeatedly.
If the coolant level in the overflow bottle is elevated after running at temp, but does not recede after cool-down, then the siphon is not occurring due to: rad cap gasket split/deformed, air is entering the system via loose hose ends, split hose ends, any condition that is allowing air to enter the cooling system.
Without a return siphon, coolant is only flowing out, creating a low-coolant condition.
Check the overflow bottle when hot, and then when cold. There should be a difference in coolant level. How old is the rad cap?
If air is continually bubbling out, it is possible to have a ruptured head gasket allowing exhaust gases into the cooling system. But, normally, if so, you would witness high op temps, and coolant being forced out under high pressure.
Simply, with a full radiator & block, plus the coolant level at the 'cold' mark on the overflow bottle, coolant will expand into the overflow bottle after reaching op temp....... then siphon back into the radiator during cool-down..... repeatedly.
If the coolant level in the overflow bottle is elevated after running at temp, but does not recede after cool-down, then the siphon is not occurring due to: rad cap gasket split/deformed, air is entering the system via loose hose ends, split hose ends, any condition that is allowing air to enter the cooling system.
Without a return siphon, coolant is only flowing out, creating a low-coolant condition.
Check the overflow bottle when hot, and then when cold. There should be a difference in coolant level. How old is the rad cap?
If air is continually bubbling out, it is possible to have a ruptured head gasket allowing exhaust gases into the cooling system. But, normally, if so, you would witness high op temps, and coolant being forced out under high pressure.
thank you
