dboldt

The 'low coolant' light is on in my 89 coupe. There's plenty of coolant. Any ideas. Thanks.

Whitecloud

Yep, same problem. You probably need a new sensor. It is the one just below the radiator cap. About a 14 dollar fix.

AGENT 86

It may just be that the system needs to be packed.

Loosen rad cap
Start motor and bring up to a temp that will open stat
Remove rad cap
Reach over and hold throttle around 2000 rpm
While holding throttle, fill rad with coolant
Put rad cap on
Release throttle

PAINTER MAN

I think that will cure your problem. Try it first anyway.

pmihaltian

Burping the system as Agent86 recommends is a good starting point. See the attached radiator burping instructions. If that does not solve your problem then, while the engine is running, look very closely and carefully for a leak in one of your radiator or heater hoses or possibly your heater core. Any pin hole size leak will cause your low coolant light to come on. It took me many months to realize that a similar problem on my Vette was a heater hose pin hole. Finally, if burping and leak search do not solve your problem, replace the low coolant sensor on the radiator.

Let us know what you discover

jfb

Engine off and looking into the rad filler with genuine low coolant, it will appear to be full. The coolant drops when the engine is raced slightly to about 1500 rpm and the thermostat is open. This makes the coolant move through the system and if it is low, the coolant will disappear from the filler. I agree, burp your cooling system first.

MK 82

Instead of holding the throttle, find a piece of wood about the shape and thickness of a popsicle stick. Put the stick between the set screw and stop on the TB and you will get about 200 RPM.

Frees your hands.

JrRifleCoach

Recently, after flushing and recharging the cooling system, I got in a hurry and didn't stop to pack it.

After a mile or so the water temp soared. I stopped for some water and opened the cap. The rad was very low AND the low level light did not come on. So after packing several times it became apparent that the system is fully charged and now the light comes ON when ever it feels like it...... This is a new sensor.

So sometimes if the light becomes a nuisance, I jump the plug to ground.

BTW the max max water temp a digi-dash will display is 299!

K87ZZ4

I thought that the coolant sensor was my problem, too. For the past couple of years, the light kept coming on--I packed it over and over again. I turned out to be the water pump, which was leaking a small amount only when running; it never left a puddle in the garage. So, the sensor was doing it's job. I believe I still have the sensor I bought but didn't get around to installing, if you need it. But, as the others said, look for small leaks first--and for a continually low/empty overflow tank.

dboldt

:Thanks to everyone for your advice. Hopefully one of the recommendations will work. cheers:

Demonic85

I think once it passes 260, doesnt really matter anymore

JrRifleCoach

The temp probe had to been in a steam pocket.

The motor is fine now.