99 z won't stop overheating!!

I have a 1999 z28 camaro. I put it in the shop to get a new hood, and when I got it back my low coolant light was on and I overheated. As soon as I could get it home, I inspected it, and realized the low coolant sensor was actually unconnected for the radiator, and allowed all the coolant to just spill out. I reconnected it, and filled it up, and for a while it worked without a hitch (although my low-coolant light would occasionally come on, I dubbed the sensor broken).

Last night I pushed the car pretty hard for about 5 minutes, got up to 130, came back down, up again and back down. After the fun ended, I was driving to the grocery store and I noticed the check gauges light came on and my temp was way too high. I immediatly pulled over, turned off the car, popped the hood, and took a look. Coolant had spilled out of the radiator cap, and was on the battery and other surrounding parts. I took it off and inspected it, and apparently it was full, along with the reservoir. Once I cooled down, I went to the grocery store (around the corner), but overheated again on the way there. I let it sit for 30 minutes, then went home, but not before overheating yet again.

I just got back from pep-boys, and bought a new radiator cap. I filled up the radiator with 50/50 dex-cool, and tightened the cap. The low-coolant light hasn't come on since, and I haven't gone an inch over 210 degrees. I'm confident I've fixed the problem, but I'm not sure.

What should I do?

Bleed the system until it's a steady stream and no air bubbles come out of the bleeder valve... The cooling system is pressurized and adding coolant or having a leak can allow air into it... When air pockets float through the engine, they can't properly disapate heat off the metal and cause hot spots throughout the engine.. Try bleeding it just to make sure.

Bleed the system until it's a steady stream and no air bubbles come out of the bleeder valve... The cooling system is pressurized and adding coolant or having a leak can allow air into it... When air pockets float through the engine, they can't properly disapate heat off the metal and cause hot spots throughout the engine.. Try bleeding it just to make sure.


IIRC, LS1's don't have bleeders

Now the Low-Coolant light is back on. What the hell!! I'm really sick of this problem, but I can't afford a trip to the dealership. I need some help here.

I don't want to open up the radiator cap unless I know what the problem is, becuase you guys are saying that messes up the air pressure in there.

The problem is basically this.. the manual specifies that when you add coolant, you can do it directly into the radiator. It says that when you add coolant, start the engine and the block should draw it in and the level should lower. When this happens, you add more until the level stabilizes.

When I did this, with the radiator cap off, I saw, as the coolant lowered, more coolant pour in from the hose that came from the engine (not the one from the reservoir tank). When the radiator cap, and proper pressure is established, isn't the coolant supposed to fill the radiator from the reservoir tank? If this is true, why would my reservoir tank be well over the fill mark, yet my low-coolant light be on? This is where the problem is. I have a brand new radiator cap on, and it worked for a while, and then the low-coolant light came on. I'm in the dark here, and I'm afraid to drive around with this light on, becuase I've witnessed it overheat because of it. I have no other car though, so I'm obviously forced. You now see the emergency for a response and succesful fix.

2nd edit:
The more I think about it, maybe it could be a vacuum leak in the o-ring of the level sensor? It makes sense, it doesn't leak coolant went it's full, because it can withstand the pressure of the coolant, but when it cools down it can't withstand the vacuum and the air just leaks on in, ****ing up the pressure entirely. Remember, when I got it back from the shop.. it overheated because it was COMPLETELY disconnected, and hanging down. Just a thought.

I had almost the same problem with my Acura. I needed a new head gasket.

:cry:



~Paul~

if i'm correct the sensor has nothing to do with overheating it only tell's you the water level is low, i ran with that light for two years.

are your fan's turning on ??

is the coolant contaminated with oil or is oil milky color ??
if so you might have a head gasket problem wich i doubt but could happen.

another sugestion is change your thermostat to a 160* one wich will help you in the long run.

if he is losing coolant then it has a lot to do with an overheating issue.

but in his case I belive that his problem was the cap. The system is designed to hold pressure. I belive that the formula is for every PSI the boiling point is raised 3 degrees. Most times it;s a 16 PSI cap. when teh cap fails and there is no longer pressure in the system the water will boil a lot sooner.

If I were you I would just keep a really good eye on the whole system untill you are confident that it's fixed

No, it's not fixed. I've taken it to two shops and each misdiagnosed it and charged me money for a bogus fix.

I changed my thermostat and found that it wasn't needed at all, and my radiator cap is brand new (18 psi). I took me reservoir out completely and blew and sucked on the hose to make sure it would withstand pressure and vacuum, and it passed my test. I also made absolutely sure the reservoir hose was tightly connected to the radiator, and it was. I even pressed a hose against the reservoir hose inside the radiator tank and sucked, and it actually would suck coolant from the reservoir. This shows how the entire reservoir system works.

I syphoned coolant from my reservoir and filled my radiator to the top. I started the engine and watched the coolant in the radiator until all the bubbles came up and it was overflowing into the reservoir. I then put on the cap and took it for a 20 minute drive (drove it hard for about 5). I came back, turned it off (at this point the low-coolant light was off becuase I manually filled it).

An hour later when I went outside to check if it was cool enough to take off the radiator cap, I turned the battery on to check the temp, and the low-coolant light was back on.

The coolant is not contaminated with anything. It's its original red (dexcool) color, and there's no metal parts or oil in it at all. The problem is clear: the coolant will overflow into the reservoir (so bad that the reservoir actually overflowed onto the ground), but when it cools down the radiator fluid level will lower when it contracts, but will not fill back up with the fluid from the reservoir (remember I checked that it's not the reservoir, because when sucked it does actually suck up fluid).

What's the problem? I'm sick of paying to fix completely unrelated problems.

dam that sucks !! are the fans turning on ? mybe the water pump :confused:

Yes my fans work. The problem really has nothing to do with the fans. The radiator works fine if coolant would get in the radiator tank. I'd drive around with a low-coolant sensor on, but it will only eventually get so low it'll overheat.

so if eventually it get's low wouldn't that mean there's a water leak

If you had read the four paragraphs I typed for you, you'd know exactly what's wrong. The coolant from the radiator goes to the reservoir as it expands, and the reservoir becomes overfilled becuase it's not being emptyed back into the radiator. This means the radiator is getting lower and lower as the reservoir gets higher and higher (eventually overflowing).

Didn't know LS1's didn't have bleeder valves.

You sure the new radiator cap is good and it's the correct psi? Sounds like the cap isn't holding the correct pressure in the radiator and allowing too much coolant to the overflow tank.

I don't know much about your camaro's( although I'm learning more every day) is your lower Radiator hose in good shape? and not collapsing. Just a thought :cool: