This constant overheating is on my NERVES!! The car is an '87 IROCZ/28 with TPI 350 (stock) and TH350 tranny with a Trans-Go shift kit. The radiator is stock, and has been rodded out by a local shop and pronounced "fine." A local wrench has performed two "dye tests" and says the block or heads are NOT cracked by the results of the dye color. EVERYTHING has been replaced, i.e., new hoses, T-stat (180), ZZ-4 water pump(new), new sensors for coolant and fans, fan motors, block reverse flushed, distilled water, tap water, coolant additives, fresh GOOD coolant, you name it, and it STILL overheats, both in traffic and on the highway, or at idle if it idles about 10 minutes. I'm at the end of my rope and ready to sell the damned thing. I can only surmise at this point, that maybe the "Dye test" ain't tellin' the whole truth, and that there IS a crack somewhere. There is no oil in the water, or vice-versa, nor does it leak coolant from anywhere. I have the fans wired to the ignition now , so that they are on ALL the time, and this doesn't help, either. Can some one give me an idea of what to do with this thing?? I have a 4-bolt block and 383 kit from Summit to build, but, my union is currently on strike, severely limiting the income. I need some VALID advice, because what I'm getting here in Nowhere, NV., obviously is not working. I appreciate ALL help!

 

this sounds like a coolant flow problem to me. some questions, with the upper hose off at the radiator have you pulled the t-stat out & checked flow from the upper radiator hose?
with everything together does the upper hose get hot? does the radiator get hot? what about the lower part of the radiator?

 

Cooling problems can be a pain. Check list
1. Air dam installed? It is under car sticking down below radiator. You must have this installed or you will overheat for sure.
2. Do your fans push or pull air thru radiator? They should pull air, use sheet of paper to check. When fan is on the paper should blow back towards motor. If it doesn't reverse polarity on the fan wires to correct.
3. Radiator cap needs to hold 13 to 15 PSI of pressure in the cooling system, check and or replace.
4. Look at the core of the radiator for obstructions, IE, bugs, dirt, bent fins, etc. Clean front and back if needed.
5. Check the coolant is flowing properly, open cap, start car and warm it up, as the car warms up to temp (180) you should notice a good deal more coolant flow when thermostat opens. This will tell you for sure that the pump and stat are working.
Hope this helps.