89 L-98 low coolant problem
Thread Starter
Racer
Joined: Nov 2008
Posts: 252
Likes: 0
From: Morehead KY
89 L-98 low coolant problem
I have an 89 corvette. The low coolant light keeps coming on and then goes off then comes on again? I check the coolant regurally to be safe, and it is never low, the radiator or in the reserve coolant, is filled up both and fine. So what could be causing the coolant light to keep coming on and going off?
Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
Try when engine is cold, start engine andremoving the radiator cap. Observe if the water level drops. Which im betting it will. I would also wait til it reaches operating tempuratures" when the thermostat opens". It might drop even more. I on the other hand have a bad head gasket and my antifreeze is being sucked out the engine exhaust pipe slowly. There are quick fixes, radiator stopleaks, that only work for a while and the problem returns. I just dont have time to tear the engine apart. Im going to try this sealer which contains real ceramic. It might do the trick. Why didnt chevy make the heads 3 inches thick between the water tubes? Uhg
Team Owner
Joined: Jan 2003
Posts: 20,306
Likes: 242
From: Summerland B.C. Canada
I have an 89 corvette. The low coolant light keeps coming on and then goes off then comes on again? I check the coolant regurally to be safe, and it is never low, the radiator or in the reserve coolant, is filled up both and fine. So what could be causing the coolant light to keep coming on and going off?
Loosen rad cap
Run motor till stat opens
remove rad cap
reach over and hold throttle to somewhere in the 2000 rpm range
while holding throttle, fill rad and cap it off
release throttle
Burning Brakes
Joined: Jan 2003
Posts: 755
Likes: 32
From: Roswell Georgia
After topping off your coolant, I would recommend checking your surge tank/reservoir level to make sure that it is cycling between the low (cold) and high (hot) marks. If that isn't happening, check for a vacuum leak in the overflow hose between the radiator fill neck and the tank and make sure that your radiator cap is working properly (any radiator shop can test it for you).I own two '89s (one auto & one 6-spd) and had similar problems with both. Worst case was a blown head gasket. (Actually an OEM gasket that rusted away and allowed coolant to seep into the combustion chamber. Found the source of the problem changing spark plugs when I saw that #7 cylinder had a green side electrode.
) The other car's problem was a cracked plastic tank high on the radiator that seeped coolant under pressure when the engine warmed up to operating temperature.Hopes this helps!
Drifting
Joined: Aug 2008
Posts: 1,921
Likes: 53
From: Philadelphia Pa
low coolant
I have the same problem in my 87. Mechanic checked out the coolant level, I've kept an eye on it. All ok. Coolant doesn't seem to be missing or leaking. Prior owner had replaced the radiator, so I looked at the sensor and it appears ok but the female connector looks buggered up as if it had been pried off of the male end, so I jammed in some tin foil for a better connection to see if that would solve the problem. It's half solved. Now the light comes on at start up and goes off after a few minutes. It doesn't come back on. So I'm figuring that the problem has to do with the connector and possibly the sensor. Would try that first.
Racer
Joined: Jul 2004
Posts: 351
Likes: 3
From: amarillo tx
coolant
hi, i had the same problem with my 1986. the problem was solved when i drilled and tapped a 1/8 npt hole in the thermostat housing and added a petcock to bleed the air out above the thermostat. also drilled a 1/16 hole in the thermostat base. then i jacked up the cars front end and added coolant until full and all air bled out of the petcock. i did not have the intermittent low coolant light any more. hope that this helps. see ya
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
solution: park on surface with incline such as driveway with a sharp up angle...radiator fill cap is lower than radiator sensor. park with nose of car angled up... with engine cool...remove radiator cap let warm up with heater on...fill coolant as needed. let temp come up fully. top off with a little rpm and replace cap. make sure res. is fill too. unless you have a leak this will do it.
(killebrew trick)
(killebrew trick)
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Instructor
Joined: Oct 2002
Posts: 121
Likes: 0
From: Hanover Ontario
Nobody mentioned the easiest thing: the sensor. I was getting an intermittent low coolant reading on my 87 after changing the injectors. Turned out I must have hit the sensor enough to keep it from connecting properly. I unhooked it then receonnected it and problem solved.
Thread Starter
Racer
Joined: Nov 2008
Posts: 252
Likes: 0
From: Morehead KY
I think that it may be leaking a little after all, found some rusty looking colored stuff around the motor. I think Ill just change out for some new intake manifold gaskets and valve cover gaskets once january rolls around, that should help i think.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
remember the sensor is just a blade of nickle plated copper, and has no moving parts.
it sticks into the water and provides a ground for a transistor to turn out the light.
no water, the light won't turn off.
it sticks into the water and provides a ground for a transistor to turn out the light.
no water, the light won't turn off.
Burning Brakes
Joined: Mar 2002
Posts: 1,035
Likes: 0
From: Atlanta Ga
I'm tracing this same type issue with my 89, to rule out the sensor can't I remove it then use wire lead and connect it to the lade and then ground to the chassis? Isn't that about the same thing?
Racer
Joined: Apr 2001
Posts: 302
Likes: 0
From: South Haven Michigan
You can buy a kit to check for exhaust gases in the coolant to rule out the head gasket. I did and had no issue. Don't forget to make sure all your hose clamps are tight and then recheck them a few times. I never had any leaks, but I noticed the overflow tank didn't seem to change from hot to cold and as last resort I changed the radiator cap and that was it for my 89.
Instructor
Joined: Sep 2006
Posts: 133
Likes: 0
From: Mt Pleasant Michigan
If you have a leak find the leak, Water pump is a good place to look they will leak out the weep hole on the bottom when the seal gets bad. Look all hoses over if they are old they can crack and leak check clamps to see if they are lose. Why would you change the intake and valve cover gaskets if they don't leak
If you are not losing coolant then look at the sensor.
If you are not losing coolant then look at the sensor.
Intermediate
Joined: Apr 2007
Posts: 46
Likes: 0
i just checked with the dealer, there is no low coolant sensor on this car, its a module supposedly that is discontinued. my coolant levels are good, but the light flickers on and off. i notice sometimes when i rev it it goes away but im thinking thats from maybe the connection on this module being loose/dirty and the vibration is whats affecting it. anyone know where this mystery module is?
Melting Slicks
Joined: Mar 2008
Posts: 2,300
Likes: 1
From: Quincy IL
I attended a question and answer setting at MidAmerica Funfest in '07. My '87 was having the same problem.... low coolant on and then would go off. I asked a C4 guru (don't remember his name) about this and he said it was very common. The sensor for the coolant level wasn't long enough. He had even fix this problem by making the probe longer. He said you could also (when engine is cold) have your car going up hill... either on rams or up hill drive way, open the radiator and you will be able to fill it even more... also to have someone raise the rpm's while filling the coolant in the radiator before it gets hot. This is what I did to fix mine and it has been fine for a year now. Hope I explained it well enough... good luck.