Low Coolant light !
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Joined: May 2012
Posts: 92
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Low Coolant light !
My 1986 Corvettes Low Coolant light keeps coming on and off. I replaced the low coolant sensor located at the radiator twice and it still comes on. The fluid is always filled as it should be. Should there be additional antifreeze added to the overflow tank or could it just be a defect in the light in the dash ?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Try warming up the engine with radiator cap off, till you can see coolant flow.
Level should drop a bit.
Blip the throttle a bit and add a little coolant.
After a few rounds coolant level should even out and not drop.
This basically purges out trapped air.
Level should drop a bit.
Blip the throttle a bit and add a little coolant.
After a few rounds coolant level should even out and not drop.
This basically purges out trapped air.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
It may also help to raise the front of the car as high as you can. With the pressure cap off, let the coolant get to operating temp. Run the engine at about 1100-1200RPM and add coolant to the base of the filler neck. Then replace the pressure cap.
There are a pair of marks on the overflow bottle; if the coolant is still at operating temp, the coolant level should be at the "HOT" line. If the engine is cold, the level should be at the "COLD" line. On my old '87, I used a red Sharpie to mark the hot line, and a blue Sharpie for the cold line. Made it real easy to check the coolant level..
Also, how old are the radiator hoses? You may have the lower hose collapsing. Can't hurt to replace both hoses.
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Joined: May 2012
Posts: 92
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I ran it this morning and when running the coolant level was down especially when I increased the RPM. I filled it to the top while under increased RPM and was able to get the cap back on before spilling all over. I'll run this weekend to see if it's still happening.
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Safety Car
Joined: Aug 2013
Posts: 4,427
Likes: 604
From: Minneapolis Mn
Good advice, it's what I've done with a little twist. I took an extra antifreeze bottle with the bottom cut out (to make a funnel) and taped it to the radiator filler and started the car. When the thermostat opens the coolant will rise into the jug temporarily then drops. That's when I filled the radiator, removed the jug and put the radiator cap on. Also keep the overflow bottle filled to the correct level. Once done it hasn't bothered since.
Last edited by hcbph; Jul 26, 2019 at 07:48 AM.
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