Trojan man

iTrader: (1)

Ok, so I'm not a newbie and I did search, but this is a bit unique....

Cliff's notes:
1. Replaced coolant sensor, cold dispstick read above hot full line, dummy light was on
2. Added coolant when cold, dummy light off.
3. Warmed up car, dummy light came back on. Added more coolant.
4. Dummy light turned off, but now Hot coolant level is near top of filler tube.
5. Either the dipstick or the new sensor are lieing to me - should I worry about the hot fill being high?


My low coolant level light was on recently and the coolant was actually low on the dipstick, so I added a bit. Light stayed on when hot, not when cold.

I replaced the sensor with a new duralast sensor from Autozone. When I pulled the sensor some cold coolant leaked out. I replaced the sensor, and BEFORE adding more fluid i checked the dipstick and it was reading ABOVE the hot line.

I started the car and the new sensor read low coolant fluid when cold, so despite the dipstick saying it was already overfull, I added some more, the light turned off.

Drove around until got warm, light came back on. Added more coolant, light turned off when hot, but now my coolant is right below the fill cap.

SO WTF, the dipstick reads high when it's low and the light doesn't go off until it's over full - ANY IDEAS? Sorry for the long post, but i'm lost.

ta12sec

iTrader: (3)

My car has been doing that for a while, never really looked into it I know theres coolant in there. Hope you find it so I can fix mine.

Kurt D

iTrader: (2)

The sensors are faulty, gm dropped them on `00+ f-bodies for that reason. Unplug it and your problem is solved.

ETA: I had a`99 so I know exactly what your dealing with. Been there done that, my `02 doesn't have it.

6speedt/a

iTrader: (1)

Agree with Kurt D had the same problem with my 98. all I did was unplug it and check your coolant from time to time!!!

Trojan man

iTrader: (1)

That's kind of the problem, i'm not even sure I can trust the dipstick.

That fact that it was reading above the hotfull mark after I pulled the sensor out and cold coolant leaked out of the radiator makes me think I can't trust the dipstick either.

Am I wrong in assuming that once the fluid drains below the sensor hole it would be under full?

M3xpress

iTrader: (1)

Since I've had my '98 the low coolant light has come on randomly a couple times when the coolant level was to the brim, I figured it was just one of those faulty little things.

I agree with the above, unplug it and keep your eye on the level.

Trojan man

iTrader: (1)

Are there any consequences to running the fluid level too high? It doesn't overflow once it reaches normal operating temperature (havne't been to a track recently, so that may cause some overflow), so as has been suggested, I may just leave it high and not worry about the light or the dipstick!

Kurt D

iTrader: (2)

I check the level in the radiator and tank every oil change. I don't think leaving it high on the dip stick will matter much.

LS6427

iTrader: (2)

Fill the radiator.......not the overflow tank.

.

67RSCamaroVette

iTrader: (63)

Dude checking the "dipstick" doesnt mean squat. It's like filling your gas tank, and checking your oil dipstick. One doesnt feed the other when the car's sitting there doing nothing. Look into your radiator cap (WHEN COLD) to check that your coolant level is, in fact low when the idiot light is on. Your overflow tank being full means nothing. If there is an air leak or a crack at the radiator nipple (below the cap,) your coolant level WILL run low in the radiator, whenever the engine temperature drops, because the vacuum that draws coolant from the overflow into the radiator is not present. Pull your overflow hose from the radiator neck, and blow into it to make sure it's not clogged. If everything's good, unplug that retarded sensor, because they're retarded. Take a look at your radiator cap, to make sure it's not fucked up and the seal is good. They hold pressure, and are designed to let the coolant from the overflow, back into the engine when the car cools. A good way to see that the radiator cap isn't working, is to look for your water pump hoses getting "sucked" flat.

graemer66

This has been an issue for me too and I went and bought a new sensor and replaced the original. Ok fault gone I thought but last week I then noticed my car was due for a Coolant change, so I have now started to do this.
I might add I am doing it in maybe an unorthodox way. I did not want to remove the plugs on the block to drain the coolant due to hearing how people have had problems with stripping threads and other horror stories, so I have come up with another idea. This being to drain radiator (motor cold or warm) then fill tap water, then repeat process for a number of drives in the car. This could be 6 or more times before the water coming out of the radiator is clear of coolant. Now as there seems to be about two and a half liters come out of the radiator when I drain it, a mix of 50/50 can not be done, Right ?, well my idea is to fill the radiator with the coolant (our Australian coolant is from Holden and recommended for the LS1) then run the car for another drive then drain using the drain at the bottom of the radiator but retain the fluid in a clean container this is about 2.5 liters.
Drain the makeup tank and put the water from the last drain into the makeup tank. Now I put the last of my new coolant into the radiator and burp the system of air, I might say I have not done this yet but will this weekend.
Gee sorry about this long story , but getting back to the sensor problem, while I have been filling and draining the system with this new sensor installed, I am getting the low water light come on , I guess there could be air in the radiator. In the end if this light stays on after I do all this I too will remove the cable going to this sensor.

Graeme Z28 1999 5.7L

graemer66

Just read a thread on another site about the dreaded coolant level sensor in the Z28 1999 Camaro's, it said there could be a link between the ratio of coolant additive to water so if the coolant percentage is lower than the correct ratio of water then the sensor will activate the low coolant light. Seems feasible I think. Quote below :

"Using the wrong level of anti-freeze and water mix. This sensor is sensitive to specific gravity and water or low amounts of anti-freeze will trigger this."

Could this be causing us some of the issues with this sensor ?, I will be changing my Coolant this weekend and see if it fixes my low water light indication.
As I am cleaning out my system at present this could be the case, as I have just about cleaned out all the old coolant, and I only have water in the system at the moment. This could be a good experiment for this theory or just another misguided thought on my part

Graeme in OZ

1999 Z28 5.7 Right hand drive Camaro

Trojan man

iTrader: (1)

I was wondering if the sensor the was just level sensor or if it had some interaction with the ratio as well. I'm running approx 50/50 and was having the issue even with a new sensor until I overfilled the radiator.

Still, even in the 100 degree midwest weather this summer I didn't run into any coolant issues or coolant light issues. So, for the time being atleast i'll leave it overfilled with the light off - if it ain't fixed don't break it.

LS6427

iTrader: (2)

You cannot over fill a radiator....they need to be 100% topped off so when you put the radiator cap back on some coolant spills out in the process.

You can do whatever you want to the OVERFLOW tank....keep it full, keep it 100% bone dry, whatever. It has nothing to do with the coolant level sensor and it has nothing to do with the cooling of your engine. It has NOTHING to do with the way the engine heats up either. I ran around for years with a 100% BONE DRY over flow tank. As long as the radiator cap is good and the engine doesn't over heat or get over pressurized, the overflow tank is useless........

I'm not saying to keep it empty......I keep mine half full now......because when you do have an issue like a small leak or over pressure issue...that coolant in the over flow tank is supposed to get sucked into the cooling system to refill it as it cools down.......((I"m still skeptical if that works or not....lol)). It should never happen though, as long as your cooling system is operating properly. It takes allot to over pressurize our cooling systems. My temp needle was buried into the red a couple times....not a drop of coolant got pushed into the overflow tank through my factory radiator cap either time. It simply cooled down and I drove to the parts store to get a new serpentine belt that flew off.

.

frisco88

iTrader: (3)

I changed my sensor last night and refilled the radiater and now when when i start her cold the lite comes on so now i don't know if the new sensor is faulty,i guess i should have left the old 1 in because it only came on when it got hot,guess i'll just keep it unplugged

red70judge

Same problem with my '99. Light on/off and the radiator is completely full
with the reserve at correct level. Good advice, will disconnect the plug to
the sensor. Now just where is the sensor plug and how do I get to it?
Thanks for any good advice.

'99 Firehawk Silver T-top 6M
'01 WS-6 Red Convert 6M

Arctic_Z

IN the same boat, help.

LS6427

iTrader: (2)

Its right under the radiator cap on the back.

Unplug it if you guys don't like the light............or get a new sensor. Thats all you can do. Filling the damn overflow tank DOES NOTHING, there are no sensors in there.

.

red70judge

Thanks a bunch. Easy disconnect. Light is off and hope it stays that way.
As they say in electronics...open legs are happy legs! Now if I can
just fix my power antenna that goes up/down but remains at about
6" from the bottom. Hope not to fork over $254 for a new GM antenna.
Will check the threads. Been through most all common problems with
these F bodies...headlamp motors, window motors, pinion seal leaks,
door panel cracks, belt tensioner squeals, now the coolant sensor, and
the antenna, torsion bar squeaks, etc. Other than the common problems the cars are fantastic high performance economy cars. This is my 8th one. Thanks again from us all.

'99 Silver Firehawk T-top 6M
'01 WS-6 Red Convert 6M

graemer66

Changed my coolant and sensor and still have the light coming on ?, I know the easy thing to do is to disconnect it but I want to investigate all possibilities before I do this. Found this info today:

http://www.aa1car.com/library/coolant_sensors.htm

And now trying to work out which one is used in our car's (1999 Z28)