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Coolant reservoir has brown junk in it and low coolant light flashing. what is it?



the sensor is either dirty or bad. its on the side of the rad, cap side, you'll see the wire leading to it.

take it out, clean it, if it still acts up, change it. this is of course providing your rad is full. yet the light comes on.
 
So you have a 2000 but how many miles? GM recommends flushing your coolant every 60-75k. It costs around $150 and is worth every penny to be honest. I have done it myself on multiple vehicles and it is a dirty, disgusting job. That and a transmission flush/fill I will honestly not do because you get crap all over yourself and it is really disgusting. Sure if you're a mechanic then have at it, but for us regular people the money is worth it.

If you have brown gunk on top of green I would tell the mechanics that and listen carefully to avoid being fleeced. Maybe the water pump is going? Maybe it is circulating corroded coolant around and fresh stuff you put in is staying on top? This would be especially true for the reservoir which has far less cycling of fluid than the radiator.

Anyway I am no expert but I am on my fourth car and I have had my fair share of honest and less than honest mechanics. Take my advice with a dose of delicious salt.
 


it has 165k on it. I have no idea when it was flushed last so I ended up flushing it. From what I was seeing the stop leak I had put in it was in the reservoir tank and completely covered the sides of it, it had an oil base but was sticky like honey. So i am thinking it was the cause of the brown junk along with god knows if the tank had ever been flushed prior to me owning it. I need a new sensor though cause the one in it is so gunked up its sad and even after trying to clean it, the low coolant still goes off. So now its just keping an eye on it. I hope its not my water pump I had that replaced not to long ago LOL
 
lol, when I had bought it it never dawned on me to see if they were using the green stuff or not i just added it in. Though I know I need a need reservoir tank cause good heavens that things is disgusting on the inside
 
Our impala's tank is all nasty from someone mixing dex and green coolant. I just soaked it in water with dish soap for a few hours, it broke up a lot of it and is good enough for me. If I really wanted to make it completely clean, I'd use my pressure washer and stick the wand in there and clean it all up. But I don't have it right now, or I would.
 
JessicaRebel said:
lol, when I had bought it it never dawned on me to see if they were using the green stuff or not i just added it in. Though I know I need a need reservoir tank cause good heavens that things is disgusting on the inside
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hot water and bleach should clean it up, let sit all day long, or over night. filled to the top.
 


02NavyBlue said:
Our impala's tank is all nasty from someone mixing dex and green coolant. I just soaked it in water with dish soap for a few hours, it broke up a lot of it and is good enough for me. If I really wanted to make it completely clean, I'd use my pressure washer and stick the wand in there and clean it all up. But I don't have it right now, or I would.
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Yeah this thing is just nasty, you can see it on the sides were the power spray wasn't able to hit it.

Scottydoggs said:
hot water and bleach should clean it up, let sit all day long, or over night. filled to the top.
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I am going to give this a shot over the weekend. Maybe hit it with the water and soap to before with the power nozzle because I am noticing the junk slowly coming off and getting into the coolant. You can see it just floating about once in a while now.
 
Do take care with bleach. If there's any trace of ammonia, (maybe from idiot who poured windshield washer into radiator?) ammonia and chlorine reacts to make toxic gas. If you see smoke coming up when you pour bleach, get away.
 
genki said:
Do take care with bleach. If there's any trace of ammonia, (maybe from idiot who poured windshield washer into radiator?) ammonia and chlorine reacts to make toxic gas. If you see smoke coming up when you pour bleach, get away.
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oh wow thanks for the heads up! good to know
 
I had this problem on my Chevy Lumina 2000; flashing Low coolant light. My coolant tank (not the radiator) had some residue stuck onto the walls. So what I did was first emptied the tank using a kitchen baster (suction tube) which you can find in a Dollar store and then removed the residue using a cloth and a wire. Make sure that you remove most of the residue. Filled the coolant tank to the Hot Level and then then flashing coolant light is gone. I think what was happening is that when the coolant used to heat, this residue used to block the coolant level sensor. Cleaning the residue in the coolant reservoir solved the problem.
 
Year old thread guy and our coolant level sensors are on the rad not in the overflow tank.

Sent from the Milky Way
 


I had a similar problem; Low Coolant light was flashing on my Chevy Lumina 2000. My coolant reservoir tank (not the radiator) had sludge/dirt on the inside walls of the tank. So what I did was 1) emptied the reservoir using a kitchen baster (you can get that in a Dollar store), 2) cleaned/removed all the dirt (using a cloth and a bent copper wire); make sure you remove most of the dirt inside the reservoir tank. Voila, the flashing light stopped blinking. So I think what was happening was that when the coolant used to get hot, the dirt from the reservoir tank used to block the Coolant Level sensor making it to blink. That fixed the problem. If this does not fix the problem, then try cleaning the Coolant Level sensor itself which is located on the side of the radiator itself.


JessicaRebel said:
Went to go to the gas station tonight and when i turned the car on the low coolant light started flashing. It hasn't done that at all today. It is always kept filled. I just had the ac compressor fixed yesterday. I opened the coolant reservoir and there is this... brown stuff in it and it looks like it is sitting on top of the green coolant. There are little bubbles and you can see the green under them. Anyone have any idea what it is? I have never had this problem before. My radiator does have a small itty bitty leak. I know they are not the best pics but I am trying to figure out if it is oil or possibly rust or god knows what. The pic of the paper towel on the tip is what it soaked up from the reservoir tank. And sorry the pics are not the best, took them on my cell. I checked the radiator cap and on the underside of it seemed to be oil. Could the place i took it for repair screwed it up when changing out my ac compressor somehow? The car is a 2000 pontiac grand prix GT. I am at a complete loss :(





Click to expand...
 
I had a similar problem; Low Coolant light was flashing on my Chevy Lumina 2000. My coolant reservoir tank (not the radiator) had sludge/dirt on the inside walls of the tank. So what I did was 1) emptied the reservoir using a kitchen baster (you can get that in a Dollar store), 2) cleaned/removed all the dirt (using a cloth and a bent copper wire); make sure you remove most of the dirt inside the reservoir tank. Voila, the flashing light stopped blinking. So I think what was happening was that when the coolant used to get hot, the dirt from the reservoir tank used to block the Coolant Level sensor making it to blink. That fixed the problem. If this does not fix the problem, then try cleaning the Coolant Level sensor itself which is located on the side of the radiator itself.
 
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