Alrighty here's some background then the prob.....I replaced my water pump a year ago with a stock water pump. I flushed my coolant lines about 2 months later cuz the chevy dealership did a sh*tty job. Well now my low coolant light has been coming on. I put more coolant in and well it still stays on. The coolant in the radiator itself looks brown and watery, so I took it to get it flushed and they told me to get the radiator pressure tested due to a water substance coming out of the radiator when the cap was popped. Had it pressure tested pressure dropped very slowly over a 20 min time frame and never went below 14psi. It is supposed to be 18. No water or coolant was leaking out however. She is not overheating or having large jumps in temp from driving to idle. (knock on wood). So wtf is goin on? Any help would be great thanks.

 

Well, for the coolant light coming on, I am guessing that your sensor is just bad. You can just unplug it to get rid of that problem.

As for the pressure being low, I really have no idea. Maybe it is something simple, like the resorvoir cap being off. I am curious about this though, so let us know when you get it figured out.

 

Well I don't know how sensitive the pressure can be but the reserve area the cap will not go on tight it will just keep turning so is that a possible reason for the problem? Sometimes the light will come on other times it won't and there is not a certain time when it will or won't come on. Sometimes it will come on after long periods of time without being started and others it will come on right when the car is started and then sometimes just in the middle of driving.

 

Well, then I think it is definately just the sensor. Mine used to do that, but now it stays on all the time, so I unplugged it. It is the only sensor on the radiator, if you want to do it. And I think all reservoir caps are like that. I doubt that could affect it anyway.

Umm...I guess you could just trace all the lines with the car running, and see if there is a leak anywhere. If you have an oil coiler, maybe it is leaking way back by the filter? Just a suggestion, so I probably am not helping.