Low coolant light
Safety Car
Joined: Aug 2013
Posts: 4,427
Likes: 604
From: Minneapolis Mn
Regardless of the year, here's some basic info that might help. If you use Prestone or comparable antifreeze it fluoresces under black light. You can use a black light to look for tracks around the engine. If you use a cooling pressure testing system, pressurize the cooling system to about 15 psi and look and listen for a leak.
In my case, I found the U shaped hose that goes between the block and tpi behind the water pump had a crack in it. I replaced the hose to fix the leak but wasn't able to get all the air out of the system. My final solution that worked: with the engine cold, I took off the radiator cap and put a coolant jug with the bottom cut out in the radiator neck and taped it in place. When the engine comes up to temp the coolant drops in the radiator at which time I topped off the radiator and capped it. At that time it now worked as it should and have been able to check fluid level via the overflow jug as you should be able to do.
In my case, I found the U shaped hose that goes between the block and tpi behind the water pump had a crack in it. I replaced the hose to fix the leak but wasn't able to get all the air out of the system. My final solution that worked: with the engine cold, I took off the radiator cap and put a coolant jug with the bottom cut out in the radiator neck and taped it in place. When the engine comes up to temp the coolant drops in the radiator at which time I topped off the radiator and capped it. At that time it now worked as it should and have been able to check fluid level via the overflow jug as you should be able to do.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The Low Coolant sensor is located just below the pressure cap. A single green wire attaches to the sensor. It could be that the syste mis just low enough on coolant that when the 'stat opens, coolant is drawn from the radiator and causes the sensor to operate.
With the engine cold, remove the pressure cap and start the engine. Let it run until the thermostat opens. You should see the coolant level drop some. Run the engine at about 1100-1200 RPM and add coolant until the level come up to the bottom of the filler neck. Replace the cap and shut the engine off.
The coolant level in the expansion tank is actually pretty low when cold. There are two marks; the COLD mark is about an inch from the bottom and the HOT mark is about 2" above that. Use a Sharpie to mark the lines so you can easily see them. The tank is easy to remove so it may be a good idea to remove the tank and clean it out.
With the engine cold, remove the pressure cap and start the engine. Let it run until the thermostat opens. You should see the coolant level drop some. Run the engine at about 1100-1200 RPM and add coolant until the level come up to the bottom of the filler neck. Replace the cap and shut the engine off.
The coolant level in the expansion tank is actually pretty low when cold. There are two marks; the COLD mark is about an inch from the bottom and the HOT mark is about 2" above that. Use a Sharpie to mark the lines so you can easily see them. The tank is easy to remove so it may be a good idea to remove the tank and clean it out.
Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 16
Likes: 0
The Low Coolant sensor is located just below the pressure cap. A single green wire attaches to the sensor. It could be that the syste mis just low enough on coolant that when the 'stat opens, coolant is drawn from the radiator and causes the sensor to operate.
With the engine cold, remove the pressure cap and start the engine. Let it run until the thermostat opens. You should see the coolant level drop some. Run the engine at about 1100-1200 RPM and add coolant until the level come up to the bottom of the filler neck. Replace the cap and shut the engine off.
The coolant level in the expansion tank is actually pretty low when cold. There are two marks; the COLD mark is about an inch from the bottom and the HOT mark is about 2" above that. Use a Sharpie to mark the lines so you can easily see them. The tank is easy to remove so it may be a good idea to remove the tank and clean it out.
With the engine cold, remove the pressure cap and start the engine. Let it run until the thermostat opens. You should see the coolant level drop some. Run the engine at about 1100-1200 RPM and add coolant until the level come up to the bottom of the filler neck. Replace the cap and shut the engine off.
The coolant level in the expansion tank is actually pretty low when cold. There are two marks; the COLD mark is about an inch from the bottom and the HOT mark is about 2" above that. Use a Sharpie to mark the lines so you can easily see them. The tank is easy to remove so it may be a good idea to remove the tank and clean it out.
Thanks, I will do it this weekend.
