Bobness

I am getting intermittent "Coolant Low" lights on my `91. The coolant level in the overflow tank is fine. Is this a common problem? Possibly a bad sensor? Anybody know where the Coolant Level sensor is located?

Vette9d1

I have a '91 also and for a while after mine was almost bone dry, even though I fixed the leak and coolant was filled all the way up it gave intemittent false codes. If you can deal with the warning light being up and check every once in a while to make sure it is false I don't think you have anything to worry about. By the way mine just went away after a week or so. Maybe you will get lucky and yours will do the same.

c4cruiser

I believe the sensor is located in the expansion tank above the heater fan. With the engine cold, remove the cap and check the coolant level. It should be right at the bottom of the filler neck. Start the engine and let the coolant temp get to where the thermostat opens. Hold RPM's at about 12-1500 and see how far down the level goes. Add a 50/50 mix of coolant bringing it to the bottom of the neck and replace the cap.

If the level in the overflow tank is at the right mark, you may have a blockage or a leak in the line between the expansion and overflow tanks. Any sign of coolant along that line??

LT195

Bobness


Your overflow tank may be fine but your reservoir for your radiator may be low. Did you check?

LT195

Storz

I was getting low coolant lights also but everything seemed to be in order, however I noticed that I would lose a little bit, so I checked around and found out I had a coolant leak on the inake manifold, its fixed now and I dont get the light anymore :D

gpagaduan

Whatever is causing the light to go off, get it looked at and fixed!!! I thought I was getting false readings and I brought it to two shops. They both couldnt detect a leak. To make a long story, I had to replace the engine due to the water getting into the block. I could've had the engine rebuilt, but the cost difference wasnt that much and I had 240k+ miles on the original engine anyway. :eek:

Steel Blue 91

If you have done any coolant related maintainence or repairs lately, you might have air in the system. As stated above, take the cap off when cold, start the engine and wait on the stat to open. Fill as needed. If you are losing coolant, you need to find out why. Mine turned out to be a leaky intake manifold gasket.

Good luck.

Juliet

First, I'm not certain if the sensor on an 87 is the same as a 91. But on my 87 the low coolant light started coming on intermittently this spring, when it was cold outside (below about 45 degrees). I'd check the level, temps etc everytime and it was always a false alarm. I picked up a new temp sensor at the local vette shop. They said it's a common problem for them to behave erratically like that. You need to drain some of the coolant out to swap it, but I never quite got around to it this past spring. Then it got warmer for the summertime. I didn't see the low coolant light for 3 or 4 months. About 3 weeks ago, with the cooler weather the light started behaving erratically again in the AM when the outside temps were below about 45 degrees. NBy afternoon I'd never see the light. Again I'd check every time and it was a false reading. Last week I flushed the rad, put in the new sensor. No more low coolant light and it's been downright frosty in the mornings here lately! :yesnod:

Wheelman

i notice mine acting up too, always seems to be in cooler weather and at cooler operating temps. Usually goes away after the car warms up.

NavyVet

My 89 used to do this. "Packed" the radiator per the instructions above 3 months ago - no problems. UNTIL YESTERDAY! I read this post, and mine came on again on the way home - 87* outside. Mine always happens when it's hot (Phoenix, duh?). Anyway, now I need to search for a leak.

codeglia

I recently replaced my old non-original radiator in my 1986 Coupe. I also had to purchase a new "coolant low" switch to install in the new one, as the new one only came with a plug where it was to go. After flushing and filling the system, the coolant-low light came on and off for about a week, despite adequate coolant levels; after that, it went away for good.

The only thing I can figure is that there was still AIR trapped in the pocket that houses the switch, and that it took a few warm-up/cool-down cycles to properly expunge the air out of that small space where the contacts of the switch reside.

BADMUDE

Well Mine has been like that since I bought it. I have done it all....constantly checking the level, flushed hte coolant, bled all the air out, replaced the sensor twice. And I still have it coming on......leads me to believe it is something else farther down the line....