Low coolant light

Ok guys the light went on and off again yesterday and I did check both levels in the radiator and the reservoir and both were full. But one thing I found is that there is some type of sludge build up on the inside of the filler neck of the radiator and under the radiator cap itself. I have a photo of it and ill try to upload it. If the photo didnt upload the sludge stuff is a very light brown almost tanish in color, plus its not really thick its actualy a thin layer of it.

My add coolant light came on. I checked the oil. It doesn't look like it is leaking into it with a head gasket gone. The coolant is coming up out of the resovoir tank.
I can see it on the side of the top and down below. Is this the thermostat? Or something else?

Thanks

Approx 2 months ago I had 2 fill my coolant, light came on checked and was low. After about a month coolant light continued to come on and off checked again periodically seemed to be ok. This week had to fill again, light still came on after filling. Now ive noticed my temp gauge is running high. Not sure what problem is not finding coolant on ground even if car is parked for 3-4 days? Also when temp gauge running high it jumps up and down alot? HELP!

I too had this light come on as well with no leaks on the ground. Found out it was leaking on the engine and really had to go in and look to find coolant leaking from some heater bypass pipe located right above the water pump. BUt not sure if this is the same scenario you have. It could be leaking coolant into the engine (like a head gasket leak) so check your oil. If you see any foam that could be it. There's no steam coming out of your tail pipe right? Also go around the engine and try and see if you can smell coolant. Has a distinct smell and may help you find the leak.

I drained my radiator and replaced my thermostat on my '97 pontiac grand prix 3.8 SE. I then got help from a teacher at school, porter and chester institute, on how to go about refilling the radiator. He helped me fill it up to the specifications. It ran well in the shop but when I drove it home, which is thirty miles away, my low coolant light came on and when I came to a stop, it turned off. I drove it for another 5 mins and it didn't come back on but during the whole time I was driving, the tempature gauge rose up a little but didn't reach the middle of the gauge like it's supposed to. It's the weekend and I need some help, any answers?

Hello. I am posting today because my 1994 pontiac grand prix is acting wierd. Well, to keep it pretty cut and dry: the car tends to cut off while driving AND while idling. I can start the car ok, drive up the block, maybe about 10-15 blocks on average, before it starts acting all goofy on me. I had the car looked at by two different Unofficial mechanics and they both(unknowning of one another) said the same thing: the engine was being choked out. They replaced the vaccum line and pcv value(i think), I think it was, its the hose that goes over the engine and also has a "plug" that goes into the engine to keep from alot of air getting into the engine. That unfortuneatley did not help. The second guy used a silicone gasket maker around the "plug" of that line that was replace, but that did not help. If more info is needed, please ask. I also can take photos if needed.
Ps. I also dont have trouble starting the car. I only have problems starting the car AFTER it has already cut off on me, which made me to believe it was not the starter. I had the battery tested as well and accoring to advance auto parts, the battery is fairly good. It has 650 cca /711 cca or something like that. Im not too hip to the car lingo. I was also told the alternator was fine and had my oil changed recently. Also, the low coolant light tends to be on but the antifreeze is filled. Actually, it is filled above the hot fill, but I was having my problems prior. The service engine light tends to come on too, but not as often as the low coolant.

Ahh. I hear what your saying. I also noticed something today that I may not have specified and I thought was kinda wierd: the low coolant light. The reason I say its wierd because it looks pretty fulll. Its at the "hot fill" line with the correct fluid, but, the car seems to shut off after about 10-15 minutes of driving as if it were overheating. And once it cuts off, the car does NOT even turnover/make a noise when trying to start it, I mean silent, as if there was not even a starter installed, silent. Just thought I had as much info as possible.

PS - the car neveeerrrrrrrr NEVER has a problem starting until AFTER it has shut off. After that, I have a problem starting it, but if I let it sit for 15-60 minutes, im ok and will enter the "on again, off again" loop again.

Yes. When it cuts off, I still have access to all those things, as if the battery was on before I turn the key any further to start the car.