My message center keeps giving me this warning "LOW COOLANT", and I can not figure it out.

It started about a month ago and I checked the fluid level and it was fine, the temp stays in the normal range on the gauge and message center. This past weekend I drained the fluid removing all the hoses and blew pressurized air through some of the hoses to force more of the coolant out. I then flushed the system and repeated the compressed air routine. I filled the system back up with 2 1/2 gal. of mixed coolant and still the same issue. Is there a bleeder valve that I do not know about or a bad signal? Anyone else have this issue?

 

I haven’t had to deal with the C5 cooling system much to be a lot of help. Is the low indicator always on, or just occasionally? Below is the fill procedure from the service manual.

1. Fill the system through the surge tank opening.
2. Fill half the capacity of the system with 100 percent DEX- COOL® coolant.
3. Slowly add clean drinkable water to the system until the level reaches to the base of the neck.
4. Start the engine.
5. Idle engine for 1 minute.
6. Install surge tank cap.
7. Cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F).
8. Shut off the engine.
9. Refer to step 3 above to remove the surge tank cap.
10. Start the engine.
11. Idle engine for 1 minute and fill surge tank to 1/2 inch above COLD FULL mark on the radiator surge tank.
12. Install the surge tank cap.
13. Cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F).
14. Shut off the engine.
15. Top off coolant as necessary, 1/2 inch above FULL COLD mark on the radiator surge tank.
16. Rinse away any excess coolant from the engine and the compartment.
17. Inspect the concentration of the coolant.

 

The sensor is known to go bad, easily.

 

The sensor is located in the coolant reservoir tank. It is part # 10405218

After Model Year 1999 Chevy switched the tank part number ( 10430189 ) and the level sensor is no longer included. As far as I can tell you have to order the reservoir in order to get the new sensor. If you order the part from a forum supporting parts vendor the price should be about $50.00 or less.

 

Try a bottle of Redline WaterWetter, about 7 bucks. Worked for me.

 

hmmm interesting in how this would fix a bad reservoir sensor...which half of all C5's have.

 

Dunno. My '99 would come on after almost every engine start. Reset and it would stay off. I got the Redline Remedy from the Forum and in my case it worked. Some sensors apparently just get a little "gummy" and whatever's in the waterwetter makes it better. It won't cure a truly defective sensor.

 

This happened to my 1998 if I park nose down on a slanted surface. If you check your coolant level and it is okay, you can reset warning. Or you can reposition or replace your tank.

Here is the TSB on it:

Document ID# 640586
1998 Chevrolet/Geo Corvette


--------------------------------------------------------------------------------

Engine Low Coolant Light Comes On (Inspect Rad. Surge Tank, Replace/Reposition) #99-06-02-016 - (Sep 28, 1999)
Engine Low Coolant Light Comes On At Start-Up (Inspect for 2nd Design Radiator Surge Tank and Replace/Reposition)
1997-1999 Chevrolet Corvette

1997 Models Built Prior to VIN Breakpoint V5104277

This bulletin is being revised to add the 1999 model year and change the part number identification procedure. Please discard Corporate Bulletin Number 83-62-11 (Section 6 -- Engine)

Condition
Some customers may comment that the "low coolant" light comes on at start-up.

Cause
This condition may be caused due to the low coolant sensor being mounted in the rear of the radiator surge tank. When the vehicle is parked with the front lower than the rear, the coolant settles in the front half of the surge tank and with the switch in the rear of the tank, the switch float may be low enough to trigger the light. The "low coolant" light may come on if:

The vehicle is a 1997 model, built before VIN V5104277, with the old design radiator surge tank.
The radiator surge tank is improperly installed in the vehicle.
The coolant level in the vehicle coolant system is low.
The float in the tank is sticking.
The coolant level switch connector is improperly connected.
Correction

Caution
With a pressurized cooling system, the coolant temperature in the surge tank can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result.


For 1997 vehicles built prior to VIN breakpoint V5104277, replace the radiator surge tank and inspect for an out of position wiring harness under the tank. To repair the harness, position the harness downward and secure with a tie strap. To determine if the surge tank is of the first or second design, inspect the low coolant switch cavity in the surge tank. If the surge tank cavity extends 16 mm (5/8 in) below the bottom of the surge tank, the tank is of a second design tank. If the cavity is less than 15 mm (19/32 in) replace the tank with P/N 10405218.



For all vehicles, check the level of the tank by viewing the lower mount on the tank. Less than 2 mm (.08 in) (#1) of the mounting slot should be visible above the attaching nut. If the gap is greater than 2 mm (0.08 in), loosen the surge tank and hold in a downward position to achieve less than a 2 mm (0.08 in) gap above the attaching nut. Tighten the bottom nut first, then both top nuts. Tighten
Tighten the nuts to 10N·m (89 lb in).

Verify coolant level in surge tank:
If engine coolant is hot, above 83° C (180° F), fill the coolant surge tank 12 mm (½ in) above the cold indicator mark.
If the engine coolant is at ambient room temperature, fill to the top of the cold indicator mark.
Parts Information
All parts in the GM Parts System since January 1997, and all parts used to manufacture vehicles since January 1997, are of the second design. If a vehicle is one of the 1997 vehicles prior to the serial number breakpoint, you may have to replace the radiator surge tank as described in Step 1, above.

P/N
Descrition

10405218
Tank Assembly, Radiator Surge


Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use :

Labor Operation
Description
Labor Time

J3250
Tank, Radiator Coolant Surge - Reposition
0.2 hr

J3250
Tank, Radiator Coolant Surge - R&R
Use published labor operationtime

Add
Reposition Wiring Harness
0.1 hr

 

I may have a used sensor laying around.

 

Last night I noticed a sweet smell from the car when I got home after work, so I popped the hood and noticed some fluid on the belt and of course in the usual spray areas. I looked for a leak and checked the fluid level which was barely lower then when I filled it. I wiped everything down so that I could check it later on after this first initial inspection. Well that was today at lunch when I heard a terrible growling noise coming from under my hood so naturally I popped the hood and the idler pulley was jumping terribly, and the needle went straight to 235. After I shut it off and looked under the hood again I noticed the anti-freeze pouring out the bottom of the water pump. Well, guess this is where I start. Fix the water and go from there. I hope this isn't the start of more repairs to come.

I will let everyone know the outcome to the low level warning after I replace the pump and refill the system.

 

Looks like the sensor was doing it’s job! Sorry about the water pump though.

 

Runs great again but I have one question, why would the sensor be saying low coolant when the coolant wasn't low but the pump was bad? Hey I am not complaining but I just don't understand how the computer would know this.

 

My guess would be the pump issue was irrelevant. The fresh coolant refill most likely flushed some contaminents from the sensor. Just a theory of course.

 

I have this problem every time I swap coolant in my Pontiac. The Redline might have worked in the above post since it lowers surface tension. My Pontiac usualy goes away after a week or two, not sure if its trapped air on the sensor or what but it happens every time.

 

Same experience with my Buick. Same day in my case, but it took awhile.

Now is a good time to replace the idler pulley also.