Okay I've got a brand new water pump, 160 degree hypertech thermostat, new radiator cap.

It is incredibly frustrating. I've got to keep adding water because it starts to boil off once it starts overheating.

I tried 2 thermostats before I decided that wasn't the problem.

I might be bleeding my lines incorrectly, the way I do it is I turn on the car and let the car warm up and open the lines. However no air comes out, only water which starts to get over everything and then I just have to add more water.

When I switched to the hypertech yesterday I opened up my water pump and there was no water in it. There was also no water in the line feeding to the top of the thermostat.

I really have no idea how to successfully bleed the lines, I find contradictory information in threads I have searched for. One person says to do it one way, one person says to do it another way.

Anyways the car doesn't overheat immediately it usually takes a while, and only overheats if it is hot outside. Its beginging to become summer where I live its already to 90 degrees i need to get this fixed!

Please HELP!!!

- Z28WannaB

 

Maybe flush the radiator. Also try cleaning the AC condensor(sp?) Just remove the hoses and it comes out through the top. Take a soft airhose and blow all the dirt out of it.

 

Also make sure your fans are coming on.

 

Make sure BOTH fans are coming on.
If they are then I would guess the radiator needs flushed.
I bleed mine by alternating between the 2 bleeders, open one for a bit then the other and repeat. It works for me.
If possible hook up a scanner and see if the temp switch is working correctly, there are 2 temp switches, one for the guage and one for the PCM. If the PCM one is malfunctioning the PCM won,t turn the fans on at the correct time.
Of course if both fans are coming on that would not be your problem but it would be helpful to see what the PCM is doing.

 

I had the same problem, one of my fans wasn't coming on even when i wired them on with the key, and changed both motors, The problem with mine was in the factory wires. So check and make sure both fans are working...if you need a fan, I have 3 good ones in my toolbox

 

I agree, make sure that the fan or both (if you have two) are coming on. Keep your hands away but let the car idle and watch for them or listen to see if they are coming on. Also, it sounds like you have overheated it several times now, be sure that the radiator isn't damaged at all. This is somewhat far fetched but last year my buddy overheated his circle track late model car. After that we kept having issues with it getting to hot. Usually it had to run a while or sit still, sometimes it was ok, sometimes it would start to boil over. Turned out that after it overheated the first time, the little cores that carry the fluid expanded, when doing so they pinched off some of the flow in areas, and also they forced all the little air cooling fins to lay over slightly crooked which then didn't allow air to flow through them. The only reason we noticed is becuase some of the areas of cooling fins looked slightly different compared to the rest of them. It was very hard to notice unless you were looking for it. We replaced the radiator and the car ran a ton better, much cooler. Like I said kind of far fetched but if you overheated it good the first time, maybe you toasted the radiator. If you have a friend with a Fbody it wouldn't take more than an hour or two to swap radiators for trouble shooting purposes.

Aaron

 

i had that problem with my z28 not to long before i got rede of it, i had replaced the themostate, the fans were working hoses fine, and flushed the radiator and it wassng clogged, so i thought it was my bleeding method so i treyd it several different ways and yet still over heating, finally i just gave in and replaced my radiator and the problem stopped thankfully but i couldnt get the ac condensor in afterwords so i just ripped out the ac compressor and lines but im sure if you take the time and do it dureing the day its not as hard as i made it to be at night :-D,

 

Okay guys, thanks for the advice. I think it might be fan related. The fan switch is new and the fans still won't come on. I don't know when they are supposed to but they only come on when the AC is on or the SES light is

Also I rigged up a manual fan switch and they only work when the car is off. If I turn the key to the on position they immediately turn off, I wired one connection to my cigarette lighter and the other connection to the H wire on my right harness on the left side of the engine compartment.

I think that harness might be bad, could that be causing my car to over heat?

- Z28WannaB

 

This seems to be a common problem for the LT1 f-bodys. My car does the same thing....fan never wants to turn on until the AC is on or theres an SES light. Im fine when im moving..sits right at 180 degrees but as soon as i stop...it just keeps creeping up and up. I think the problem is the PCM is set to turn the fans on way to hot. but i think it can be reprogramed

 

Mine won't ever turn on the heat just keeps going, and once its heated up to 210 when I stop it the needle looks like its gone sky diving.

- Z28wannab