yes, i have done a pressure test. it does hold its pressure without a problem. There wasnt the slightest drop on the gauge.

and i wasn't saying it was a design issue. i was just trying to describe how the engine is set up in case you havent worked with this engine much. since you said the radiator cap should be the highest point in a car, i was just saying whats higher than that in mine. Just trying to give as many details as i can.

 

if its not in the engine side of the system it has to be in the radiator side. radiator cap, overflow tube/system

 

brand new radiator cap, and i took the metal rod in the coolant tank out, as well as that hose and threw it away. I took a new metal fuel line pipe and cut it to the same size, and put a new heater hose running from that to the radiator just to rule that one out. And the bushing fits nice and snug as well. The fans are on a switch. I made a functioning grill so air goes right to the radiator, as well as the scoop shoving air up there. The new thermostat in there right now is a 180 that I got a few weeks ago. I did a coolant flush at that time as well. Did the pressure test last week. New upper and lower radiator hoses. I also replaced the little 2 inch heater hose going to the water pump. Im about to replace the hoses and lines coming from the heater core. I dont know if those metal pipes are getting blocked up or not, so Im going to put straight heater hose from the heater core lines, to where the hoses normally connect. I also raised the battery up off the tank an inch and a half so it wouldnt pinch the new overflow hose. Cooling fan is always on, the relay blew out so I put it on a switch.
I think thats all I have done. I cant think of anything else right now at least. Hopefully that helps. I just feel like the thermostat keeps sticking for some reason. Everytime I change it, things are fine. But shortly after it goes haywire again. But I dont know what would cause them to keep going bad so quick.

 

and like i said, it will purge from the overflow tank. and the only hose thats still cold when everything is hot, is the upper radiator hose.

 

The reason for the bleeder screws on the LT1 is because the cooling flow is reversed. On your engine, like mine, coolant is pumped through the block, then out the thermostat housing to the radiator. A bleeder hole in the thermostat will aid when you're filling, allowing the air to pass through and letting the coolant make it's way to the thermostat. The thermostat registers coolant temperature, not air temperature, so if air is getting trapped initially at the stat, it won't open.

 

well apparently i had the flow backwards in my head. so what youre saying is if the upper radiator hose is the cold hose, than something is blocking it just before it gets to the radiator. which still cold be the thermostat. but the reason its purging from the tank is because its trying to push coolant through the block but there is no exit so to speak. correct?
so a bleeder screw wouldnt really help me on the housing, but since the thermostat is in the housing, theres no real way to make a bleeder for that either. so thats why there isnt a valve on these cars, because there was no logical way to incorporate one.
So if everything else checks out, then am I seriously just getting faulty thermostats like that constantly like some twist of bad luck? Should I try a 170 or 160 to see if it will stay open easier since its supposed to stay open more often?
Just when I thought Ii knew everything about these cooling systems. Now my head hurts. haha

 

The upper radiator hose being the cold one means coolant isn't flowing out the block and to the radiator. If you drive the car in the winter, and want interior heat, then I wouldn't go with a stat colder than a 192. Definitely drill a bleeder hole in the stat, unless the new one already has a hole. Doing that isn't going to affect your engine cooling in any negative way.

 

im not worried about heat in the winter. its going on summer right now. and i can always swap out the stats when winter does come around. but ive never even heard of the thermostats themselves having a bleeder, much less know how to go about making one on a stat. how would you even access it with the housing over top of the stat?

 

You drill a hole and that's it. It's not a screw type "bleeder" like what you're thinking.

 

take the thermostat out and see if that fixes it. if so you found the problem. are you putting it in the right way, some are easy to get in upside down.