Two things actually.

1). On the digital dash cluster the toggle between Battery volts and coolant temperature. When flipped to Battery works fine,when flipped to Coolant temperature it reads: LO. It never shows any number.

2). On the screen in the middle of the console I keep getting intermittent "LOW COOLANT".

When I check the coolant it is full.

What and where should I check? Thanks all.

 

Have you recently worked on the system? Maybe it needs “burping”…?

 

A shop replaced the radiator almost a year ago. Also to note I never see coolant in the plastic overflow tank.

 

My coolant temp displays fine, but I get the low coolant light randomly as well. My oil temp display always says LO, I figured I just needed to replace the sensor.

My overfill tank is full of nothing but brown crud. Should I get that out?

 

Yes. Get you a turkey baster and suck that crap out

I don't know where the "low coolant" sender is but you need to see coolant in the overflow tank otherwise you wont know if the radiator is completely full or not.
Gary

 

There are only 3 10mm screws holding the tank in. Go ahead and take the clamp loose, remove the 3 screws and pour out all the crap in a safe location. Might as well clean up the inside as well. I used some Dawn dish soap, a little bleach and a degreaser for the tough spots. Get a wire coat hanger and wrap a small rag around the end to scrub the inside. You can bend the coat hanger around to get to all the inside.

Might as well flush the whole system and refill with new coolant if the inside of the radiator looks as bad as the overflow tank. Use distilled water and fill and drain several times until it comes out clean. Then refill with coolant and distilled to proper levels and protection for your climate. Burping procedures are different for the different engines, check your FSM for proper procedures.

Good luck!

 

Some other forum member suggested to add some small rocks and shake it up while you have it out. I tried it, and it worked great

 

If there's no coolant in your overflow tank then the coolant level is low.

Does the digital readout work for the oil temp? Is your coolant analog gauge working? If the coolant level is too low the temp will be on the high side.

 

I used some large stainless steel nuts that worked great too.

 

Necessity is the mother of invention

 

I should clarify. My Vette is a 1986 base coupe. There is no analog temp guage. Not sure how much that info changes things. Also yes the oil temp/pressure works just fine. Only thing not working is the Coolant temperature. Always displays "LO"

 

Alrighty then..I can see that none of you (thankfully) has been a truck stop waitress As any good waitress would know.. cleaning out a crusty thermos is a easy task with..Ice..yes Ice is the answer we were looking for
But good thought, if it looks dirty a through cleaning would be in order. Cant believe its that easy to get out

Gary

 

I will clean the coolant overflow tank tomorrow. Lets see, rocks,stainless steel bolts or ice. I think I will try the ice.

I checked my coolant level this morning at the radiator and it looked full?

What controls the two displays?

 

..anyone?















Bueller.......

 

jrzvette nailed it on the head when he said if there is no coolant in the overflow then it is low.
You cant check the coolant by looking in the radiator.

As for what controls the displays I don't know. Just got a set of service manuals but haven't begun to dig through them yet
Gary

 

Coolant Display is from a Sender which is a Thermistor threaded into the Right Head between Cylinders 6 and 8. Thermistors lose resistance as they heat up so if there's a reference voltage attached to it, more of that voltage reaches ground as it warms up. The voltage drop is interpreted as temperature on your Display. Anyway, with Lo being shown - no voltage drop - it's probably disconnected or the wire is broken. See if you can find it (it should be a blue or green wire) and then to check the Display, ground it against the engine. That should give you Max or something around 300 degrees. If it does, making sure there's a good connection at the Sender should get your Display working again.

None of what you're seeing on the Display is used for Engine Management. The ECM uses another Thermistor or Coolant Temp Sensor which is threaded into the Intake Manifold below the Throttle Body and that signal is used for idle/low speed Main Fan Control. The ECM also delivers fuel - pulses the injectors - based on Coolant Temp. Coolant temperatures/overheating/ can be checked by using a scanner to see what the ECM is getting from this Sensor. You can also compare it to your Display to verify the Display's accuracy. Because the Sensor/Senders are in different locations, there are often a few degrees difference in temperature, but a large variance would indicate a problem.

Low Coolant Indicator is through a Module that's buried in the Passenger Side of the Dash. It sends a low voltage a/c signal to the Sensor in the Radiator and as long as that Sensor is covered in Coolant, it's resistance is low (10 ohms or less as long as it's covered in Coolant), so most of that voltage is grounded. As long as that's the case, the Light - driven (grounded) by the Module - should be out. When the Sensor isn't covered, it's resistance is 45 ohms or greater. Since the Light is working, the Module is probably ok (which is good because it's no longer in production) and the problem is probably in the Sensor. To verify, disconnect it and ground the wire - the Light should go out. If so, replacing the Sensor should fix it. It's difficult to measure Sensor Resistance because it has to be immersed in a liquid, but I guess you could remove it and put it in water and then try to test it with one of the DVM leads on the side that's in the water.

 

Thank you very much. I will update my findings.

 

Ice, what the hell is ice

 

I just lit off a M80 in mine, cleaned it real good

 

Like sun said the temp sensor is between cyl 6 and 8. If the circuit is open it will read lo. Check to make sure the wire is hooked up and the connection is good. If that checks out throw a sensor in and you should be good to go.