Low coolant light stays on?

[96lumina]

I just got my 96 Lumina thru a good friend, and the car belonged to his beloved Mom...it sat for about 13 months and all I did was check all fluids and install a new battery...his Mom was one of those old ladies who would take their car to the shop for service all the time to have a piece of mind that all was good...the car has just under 108K and all is good...it runs like a new engine, clean oil and trans fluid...the coolant was a tad low and still had the original orange stuff in it...there was also this oily kinda rusty scale that was in the neck of the radiator, so I wiped it off will a shop towel and it just seemed to be like very fine oxide scale that had built up over the last 14yrs with not having a coolant service...I will flush and go green very soon, trust me.

My question is that my low coolant light stays on...I found the sensor attached just below the rad cap...do I need to pull this sensor and give it a cleaning or should I just replace it with a new one?...I'm not sure if they can be cleaned or not, I'm just thinking that it is probably covered with some of the coolant gunk and that is why my light stays on.

I also checked the cooling fans to make sure they work and they do...it took about 35 minutes at idle cuz the motor runs great...actually after 35 minutes I gave it some throttle to make em come on cuz the coolant was staying a constant 180-184 at the T-stat....it could have idled another hour or more and still no fan...I'm pretty sure the car was well maintained except for the coolant

Any suggestions?

[bszopi]

Welcome to the site!

You may have some air in the system, which could be causing the light. Best way to check is find the purge valves (1 should be on top of the waterpump, other will probably be around the thermostat), and open them up slightly with the car running. You want a solid stream of water to come out. If there is air in the system, it should come out with these open. Then, be sure to make sure the coolant level is topped off in the radiator and overflow tank.

Cleaning the sensor may also help out. I remember having to clean my overflow tank before (where my sensor was located) due to the light staying on.

[96lumina]

bszopi, thanks for the reply...I did check the bleeder screw and topped off the overflow tank and radiator as well...my bleeder is located at the T-stat housing and all is good...unfortunately my sensor is located on the side of my radiator a few inches below the cap...maybe I'll just have to get a new one and change it when I do my coolant flush...I just wanted to find out if others have had the same problem and if the sensor could be cleaned...thanks

[86FieroSEv6]

Don't bother cleaning it. They go bad all the time. On rare occasion the fault is with the instrument panel. Disconnect the sensor, if the light goes out on restart then it is the sensor that is bad. If the light does not go out, then the circuit and instrument panel will require testing. When replacing the sensor, you won't really lose that much coolant. The "goop" you found in the radiator neck is the result of air in the system promoting corrosion. GM has had a huge black eye on the Dexcool "goop" issue. The key to using Dexcool is to prevent any air in the system, make sure the grounds are all good and don't let the vehicle sit for extended periods. Better to use a silicate free hybrid organic acid type coolant. I have also had good results with the long life universal green found at common auto parts stores such as Advance or O'Reilly Auto Parts.

[96lumina]

86FieroSE, thank you so much for the info...I will buy a new sensor and let you all know what's up...the info you gave about the orange coolant was very helpful...I hope others will appreciate the tip...until next time...I'll be back with an up-date.

[pocket-rocket]

The sensor in my 92 is stuck. I just left it unplugged and keep an eye on fluid levels and it's been fine so far. I might get a new sensor down the road though.

[96lumina]

Wanted to finalize my thread...thanks for the post guys...I got a new coolant sensor($4 @ AutoZone and it works great now...the old one was corroded very bad...during the radiator flush the light would come on when the t-stat opened and coolant would drop...when I added more coolant the light went out...the only hard part was swapping out the sensor which was on the side of the radiator.

All is good now