Started the car up after adding some coolant to the engine (leaking quite a bit) and ran the engine for about 20 minutes, first let it idle warm up, then i began to push through the various rpms up to 3k. Engine did not overheat( according to guage it remained at about the 1/2 mark) well after that i shut the engine off only to hear this subtle sound of fizzy/boiling water sound near the rear of the block, i couldnt get under the car because of the uneven dirt/gravel driveway. Now maybe tomorrow i am going to pull it in the garage and jack it up. i have 2 current suspicions what the problem is: Hose to the heater core is loose/cracked, and maybe seeping out. Or i am leaking coolant somewhere in my block, possible blown head gasket.

Im hoping if it is one of these problems, its the heater core hose. Any other thoughts yall? Thanks

 

it could be the steam pipe that goes from the drivers side head to passenger side head then up to the throttle body area

 

You have a leak back there obviously. I'd check that steam pipe just mentioned and if it isn't that it may be a blown head gasket or a cracked head or both. Make sure it isn't a heater hose.
Jim

 

also check coolant tubing by pasenger header. They are known for getting burned there after headers. I heat the car up like you did, and then try to get underneath it to get closer to the sizzling sound. I bet it is coolant/water hitting your hot exhaust.