have an 85 iroc 305 tpi. came to park it in the driveway after a car show and there was a good coolent leak coming from the pass. side dripping off the starter. so put the car in the garage for a week then jacked the car up and started to look for the leak bone dry everywhere, checked all hoses. looks like i lost about a quart of coolent. checked the oil it was fine ( no coolent ) so i put my coolent pressure tester on the system and found no leaks and the pressure never went down????? couple hours later i go back out determined to find this leak and when i put pressure to it again i found a leak on the bottom pass. side of the firewall so i thought heater core! put in a new heater core and idled it for 40 mins no leak problem solved?! NO i drove it to town to get gas and was leaking ing the same damn spot..

heater core is not leaking checked it again also the heater core hoses are tight and not leaking..

when it does leak it seems to start leaking when the engine is cut off, it leaks about a quart then stops..

also NO intake leaks and oil looks clean just keeps dripping from that little flange towards bottom of fire wall pass side.. thanks

 

Check where the hose from the heater core connects to the back of the block. That's the only thing I can think of.

 

Could be like mine and have rusty freeze plugs.

 

rust colored coolant is most likely freeze plugs.. whats the coolant color?

 

the coolent is very clean but only a year old freeze plugs look nice i thought the one heater hose went to the radiator and the other to the front of the intake i never checked a back one

 

Oops ... my fault. I thought it went to the block but it doesn't. Here's a TPI coolant diagram. Might help you find your leak:



My hunch is one of the two connections that run from the heater core back to the radiator.