Maverick69

I just did a rebuild after a blown head gasket and the car is still overheating. The heads have been fully done up and pressure tested. We have replaced the water pump, thermostat, full coolant flush through radiator with new dexcool. Bled the whole system a couple of times and there doesn't seem to be any air left in any of the lines or the waterpump. Started it up and it's still overheating. I then put pressure onto the radiator, which by the way is clean and flowing, and pulled all of the spark plugs out to test and see if any cooland was getting back down into the cylinders. Turned the crank and and looked for anything to come out of them, there was nothing there so it's good. I then did the opposite and put shop air back into each cylinder one at a time and topped off the radiator to see if air was getting back up to the cap. Nothing everything is holding up. Put everything back together and started her up. still overheating a bit. I have tried it with the thermo out and did a test on the thermo to see if it was opening and it is. There is nothing abnormal coming out of the exhaust. Engine seems to be running well except for the overheating. The whole engine was out so everything was cleaned on it.

I don't know what is going on and it's starting to drive me nuts. Does anyone have any ideas on why it's overheating still?

96 Z 28

When I swapped out my Coolant Temp Sensor & Thermostat, I had to use both bleeder screws and do it like 15x. LT1s just really suck up a lot of air into the system.

I would just bleed it out a few more times. I pretty much knew it was air as my top hose never got hot to the touch and it stayed soft (IE no pressure) until the 15th time.

Is there coolant in the overflow tank?? How bout the radiator??

FastandBlue

Another thing to keep in mind is whether or not you were able to fit in the total amount of coolant your engine calls for. If you didn't but drained the engine completely, you prolly have air somewhere.

Injuneer

What temperature are you calling "overheating"? Are you reading that off the dash gauge, or via a scan of the PCM?

Have you verified that the coolant temp sensor in the water pump housing is accurate? Have you verified that the dash gauge is reading correctly, based on the accuracy of the sensor in the driver's side head?

Courtesy of Shoebox:

http://shbox.com/1/4th_gen_tech2.html#ect

Have you verified that your fans are coming on at the correct temperatures? Low seepd at 226*F. high speed at 235*F?

When you replaced the thermostat, did you use the correct/unique LT1 thermostat?

Z28kev

did u try replacing the radiator cap?