So I just recently bought a 97 Camaro Z28 with the 5.7l LT1 in it. I owned a 98 camaro with the 3.8 a few years back and loved it. Also had no problems from it other than an exhaust manifold leak. I’ve always wanted the V8 version and now I’m ecstatic to have one. I know a little about motors, enough to find my way around and to make repairs, but a lot to still learn with diagnosing things. So on to the main problems. I had autozone run check the codes and got a whole list back, including the crankshaft senser popping up a few times. That explains why it doesn’t want to start sometimes until I give it a little gas. My main problems right now are with cooling and the brakes.

So with the cooling, I’ve changed the coolant and the thermostat, and then followed that by purging the air out(which I learned how to do from these forums). My first fan kicks in and works. It usually comes on pretty early. But the car still tries to over heat. It goes on a constant rise until it passes the third white mark at which I’ll pull over and turn it off. When I first bought the car, I drove it 80 miles home and it never passed half way. Now I don’t know where to start to fix this.

With the brakes, I changed the calipers and changed the brake fluid. Not sure where I should bleed it at which could be the problem with the weak breaks. Pedal was spongy at first but now it feels firm. It just seems that I don’t have a lot of stopping power.

 

CODES:

What were the specific numerical codes? Did any of them related to the coolant fan relays?

The crankshaft position (CKP) sensor is only there to diagnose misfires. It wasn’t even used in the 93-95 OBD-1 LT1’s. It was added in OBD-2 in 96 to detect misfires. It does not affect starting or how the engine runs. The PCM gets (pseudo) crank position data from the optical cam position sensor in the Optispark distributor.


COOLANT TEMPERATURE:

Stock programming - Bothfans turn on at low speed at 226°F. That is a bit more than 1/2-way between the middle mark (210°F) and the 3/4 Mark (235°F). Both fans go to high speed at 235°F, what you are calling the third white mark. Note that the dash gauge and the PCM are fed by separate coolant temperature sensors. The is no guarantee that both sensors report the same or even correct temperature. Since you turn it off when it hits the third white mark, have you ever let it runs past that mark to see if the fans go on high and pull the temperature down?

If fan relays are bad on the signal (from the PCM) side, codes will set. But there are no codes related to the load side, which is 12 volts direct from the red “+” box at the battery. There is a fusible link in that wire. You need to verify the 12 volt supply is reaching the relays, and that the relays are passing 12 volts to the fans when the PCM activates the relays.

Check both coolant temp sensors to see if they are accurate, and receiving the correct reference voltage. Shoebox has a guide. Did you use Shoebox's guide for bleeding the air out of the coolant? Are you sure you have the correct LT1 thermostat?

4th Gen LT1 F-body Tech Articles

4th Gen LT1 F-body Tech Articles

http://shbox.com/1/tstat.jpg

Since this seeming overheating is a new problem, have you checked:

- for an obstruction in front of the radiator, plastic bag, etc.?

- is the air dam under the bumper still in place and undamaged?

- test the radiator cap to verify it is holding 18 PSI.


BRAKES:

Was there an ABS code present when you decided to change the calipers? If so, the ABS motors need to be “rehomed” with a GM Tech 2 (or other high end 2-way tool) before the brakes can be correctly bled. When bleeding, did you start with the two bleeders on the ABS motor pack?

Best thing to do is download (free - courtesy of GaryDoug) the factory service manual and review the section on BRAKES to insure you are following thecorrect procedure. 96 manual is basically the same as 97:

https://www.mediafire.com/?40mfgeoe4ctti