I noticed the past 2 weekends that when I let my car sit for 2-3 days without driving it the low coolant light will come on. I checked it and it was a little low but not too bad but the overflow bottle has plenty in it. So my question is why isnt it taking the coolant from the overflow bottle? Is there an air pocket thats keeping it from getting sucked in or if the overflow bottle is too full (which is now the case) will it not work correctly? I noticed whenever this has happened lately that we'll have one really nice day (50+ degrees) then a really cold day (30 or below) dunno if the drastic temperature change has something to do with it??? Any ideas?

Myles

 

Your low coolant sensor may be crapping out. Mine did the same thing. Radiator and overflow was full, but light was still on.

 

Check the radiator cap. A faulty radiator cap will not allow the cooling system to work properly, and you will get low coolant in the radiator, but still have a full overflow. Some parts stores like kragen, auto zone, pep boys have testers. Or you could just buy a new one. If that doesn't work, then start looking for leaks.

 

im having the same problem.......my coolant light is just coming on when the coolant bay is full ........im about to do a full system coolant flush................ill let you know how it turns out

Scott

 

The coolant in the radiator is a little low so the light does have a reason to come on and the radiator cap is new, its maybe 2.5 months old if that. It could be defective though and I did buy it from autozone so maybe I'll have it tested. What I've been doing is when the system is hot to loosen the cap just a little and the coolant will come out a bit and the light will go off cos it will fill itself back up, so maybe it is the cap.

 

Make sure you got an 18 psi cap.

 

I made sure to get an 18 PSI cap. I bought another one today to see if the radiator cap I had is faulty and if that is causing my problems. I think I'm also going to take my overflow bottle out and empty it and put the amount that its suppose to have in it and clean it while its out. Hopefully this fixes the problem.

 

Kind of an update I guess. I noticed if I drive it around its ok but once I turn off the car and let it sit it somehow gets air into the system and then the next time I start my car it will start to overheat so I turn the bleed screws and huge amounts of air will come hissing out then some coolant will eventually come out but then it will still have a lot of air in it here and there then by this time the low coolant light will come on. Dunno what the problem is I put the new cap on and dunno what else could be causing this. I just cant figure out how all this air is getting in the system. Any help is greatly appreciated

Myles

 

Hopefully you don't have a head gasket problem. Is it actually consuming coolant? Have you checked your oil for any coolant?

 

It doesnt seem to be consuming it I think its just keeps going into the overflow cos it did just that before, it overflowed and there isnt any condensation coming out my exhaust except for the normal water from my cats but I havent checked the oil but I don't feel thats it, or maybe more hoping than anything, but I think its jsut something screwy going on witht eh coolant system. I was also having those heater core problems before so I dunno if that is playing a part in this. I got the day off tomorrow so I'm going to go through everything as much as possible see if I can figure out what the **** is going on.

Myles

 

my friend had yr problem to, and shoebox is right, had lots of air in his system cause by a small leak in the head gasket, hope this isnt yr case

 

If it is the case I might as well buy new heads if I'm gonna go through the trouble of taking them off.

 

My low coolant light comes on constantly. I have plenty of coolant and the engine temp is good, so i think the sensor is bugging out,do any of you guys have any links on where to get a new one?

 

Well I'm still trying stuff and nothings fixed the problem yet. I took out the coolant overflow bottle and cleaned it out and made sure the line going to the radiator wasnt blocked or anything and it was fine. I put on a brand new 18 pound radiator cap and still having problems. I noticed when I try and bleed the system by the bleed screws the top one will bleed just coolant but the lower one near the thermostat will keep sputtering and shooting out air and coolant and no matter what keeps doing it. Would this mean that maybe my seal on the thermostat is no good or the thermostat itself is no good? It's fairly new, I put it on a few months after winter started and its a 180 degree and I have a 160 still so maybe I should swap them out? This is pissing me off, I hate it when my car doesnt work right, its like having a friend in the hospital. I also checked the oil and no signs of coolant and nothing is coming out the exhaust. I might bypass my heater core and see if that does anything cos I was having problems with that earlier. Also, could this be a sign my waterpump is going?? My car has 91,000 miles on it. Car runs great otherwise, no loss in power or anything like that.

 

I had the exact same trouble with an '84 Fiero. I changed everthing; thermostat, water pump, front and rear hoses, removed and cleaned the radiator ...flushed everything. I still had the problem and the car would over heat. Guess what it ended up being?.......a hair line crack between the intake and exhaust valves of one cylinder's combustion chamber. I never thought it would be the head since I never had coolant smell or steam in my exhaust but I pulled the head since it was the last thing left to check (as always)
If you do have a craked head it would account for all your symptoms. Do a leakdown/ compression check before you tear it all down though. Do you have a puff of steam/smoke on start up?