Low Coolant after coolant flush
Thread Starter
7th Gear
Joined: Apr 2018
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From: Woodstock GA
Low Coolant after coolant flush
So I bought my first Vette about 3 months back and I have been loving it ever since. I ended up finding a great deal on a 1997 C5 with 48,000 miles and in great condition. It was about time for an oil change so I took it over to a shop that sells and services Vette's in the area. I had them do an oil change, coolant flush, and transmission flush. I did this as I was not sure when the fluids were changed last and I wanted to be sure they were not original or 20+ years old. I then put about 100 miles or so on the car and everything has been fine, until tonight. I was at a red light scrolling through the DIC just to check temps etc and a "LOW COOLANT" warning popped up. It seemed to lock the DIC as I couldn't scroll any more. I looked at the analog temp gauge and it appeared fine. The light turned green and I went with the intention of pulling over at the first chance I could. I cleared the intersection and the warning went away like it was never even there. I then pulled over and checked the temps on the DIC and everything was fine. I turned the car off and opened the hood and checked all the fluids, everything looked great and exactly where it should be. This seems very odd as I was on level ground so I don't think it would have thrown off the sensor. Does this seem normal or is there something that should have been reset when the coolant was flushed. Any ideas? Thanks for the help!
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Possible "air bubble" in the system, that was not purged initially.
May want to check coolant level when the car cools off again.
May want to check coolant level when the car cools off again.
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Thread Starter
7th Gear
Joined: Apr 2018
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From: Woodstock GA
Thanks for moving the post, sorry about posting in the wrong section. Still new here and trying to learn the ropes. So it has been about 2 hours since I got back and just checked the coolant again. It is exactly where it should be. I am going to let it cool down all the way over night and check it again in the morning.
Safety Car
Joined: Jul 2010
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From: Chandler AZ
What if the coolant tank has been replaced with a non float level tank?
I did this on my 1999 with a Dorman replacement tank, I had to make a "jumper" wire to plug into the harness plug that used to go on the original tank.
If someone before did this, maybe the jumper fell out?
#2 possibility is the float is dirty/scummy and stuck in the down or "low" position.
On my old 1994 grand am the float has gotten stuck in coolant tank, I can't see the float.
What I did to get rid of the low coolant light was to unbolt tank and shake the tank up and down pretty hard while engine was warmed up.
Light went off.
I tried shaking it while engine was cool several times and got nothing, I think it being hot helped the float pop back up.
Of course the reason float got stuck down, the car had a small coolant leak.
#3 is the possibility the float switch is bad.
If you want to not mess with it anymore, I would just unplug the harness from underneath and make a jumper, on mine I used a big paper clip bent into a U shape.
Then stuff it back under tank and bolt tank back down.
I did this on my 1999 with a Dorman replacement tank, I had to make a "jumper" wire to plug into the harness plug that used to go on the original tank.
If someone before did this, maybe the jumper fell out?
#2 possibility is the float is dirty/scummy and stuck in the down or "low" position.
On my old 1994 grand am the float has gotten stuck in coolant tank, I can't see the float.
What I did to get rid of the low coolant light was to unbolt tank and shake the tank up and down pretty hard while engine was warmed up.
Light went off.
I tried shaking it while engine was cool several times and got nothing, I think it being hot helped the float pop back up.
Of course the reason float got stuck down, the car had a small coolant leak.
#3 is the possibility the float switch is bad.
If you want to not mess with it anymore, I would just unplug the harness from underneath and make a jumper, on mine I used a big paper clip bent into a U shape.
Then stuff it back under tank and bolt tank back down.
Safety Car
Joined: Jul 2010
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From: Chandler AZ
In case you were wondering why I put on a non float level tank, my original tank started leaking, and the replacement tanks with float are about 2 times as expensive.
When I found out newer C5 Corvettes, maybe 2001 and up came without tanks with floats, I felt less concerned about the float type tank.
GM probably eliminated it due to low coolant lights coming on, or to save $$$.
I did this in September and it has been fine, I check the coolant once in a while with that line while cool.
I also watch coolant temps often on all my vehicles.
When I found out newer C5 Corvettes, maybe 2001 and up came without tanks with floats, I felt less concerned about the float type tank.
GM probably eliminated it due to low coolant lights coming on, or to save $$$.
I did this in September and it has been fine, I check the coolant once in a while with that line while cool.
I also watch coolant temps often on all my vehicles.
Thread Starter
7th Gear
Joined: Apr 2018
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From: Woodstock GA
So I checked it again this morning and everything looks fine. The coolant is right at the line. I guess I am just going to keep an eye on it for now. As it has been mentioned maybe the float got stuck or it had an air bubble in the line.
Racer
Joined: Mar 2018
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From: Frederick Colorado
I guess the "that's a FEATURE, not a BUG" attitude pervades the design teams as well as the management and <shudder> the Sales/Marketing people, too.
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Thread Starter
7th Gear
Joined: Apr 2018
Posts: 7
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From: Woodstock GA
So looks like it tripped again on the way into work. I spoke to the shop who did the coolant flush for me and they recommended changing the tank. They said the sensor would be in the new tank. Any ideas? Do you think I could just clean the sensor or anyway to buy just the sensor? I have only seen the wire plug but cant seem to just find the sensor for a C5.
Safety Car
Joined: Jul 2010
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From: Chandler AZ
If I have my old tank, I'll look at it and even take pictures.
On my 1994 Grand Am and the original tank on my 1999 Corvette, neither of the floats were visible or reachable while mounted on the cars.
You could try what I suggested with getting the coolant warmed up and unbolt tank, and shake it up and down, especially putting a quick thrust on the down motion to try to get that float to pop up.
If it works, most likely you won't have to deal with it again, unless there is a leak.
This just takes your time and effort.
On the Grand Am it finally stopped doing it (float stuck down and making message show on dashboard) and I was cheap not wanting to buy a new tank as it was fine otherwise.
On my 1994 Grand Am and the original tank on my 1999 Corvette, neither of the floats were visible or reachable while mounted on the cars.
You could try what I suggested with getting the coolant warmed up and unbolt tank, and shake it up and down, especially putting a quick thrust on the down motion to try to get that float to pop up.
If it works, most likely you won't have to deal with it again, unless there is a leak.
This just takes your time and effort.
On the Grand Am it finally stopped doing it (float stuck down and making message show on dashboard) and I was cheap not wanting to buy a new tank as it was fine otherwise.
Safety Car
Joined: Jul 2010
Posts: 4,003
Likes: 386
From: Chandler AZ
The failure on the original C5 tank was the nipple for steam line had a crack, and that little tube was popped out on it's own after pulling steam line off, I'm assuming it's purpose is to add reinforcement, also the other nipples appear to have tubes in them also.
I took cap off and doing all angles looking in, you cannot see the float, the float doesn't appear to come out, so you can't really get at it to clean or replace.
If you buy a new tank with the float and either replace yourself or have shop do it, you don't have to mess around anymore, 110.00 or so for AC Delco September 2017 as I recall.
I took cap off and doing all angles looking in, you cannot see the float, the float doesn't appear to come out, so you can't really get at it to clean or replace.
If you buy a new tank with the float and either replace yourself or have shop do it, you don't have to mess around anymore, 110.00 or so for AC Delco September 2017 as I recall.