My car has no pressure in the cooling system. It appears to be circulating, but no pressure. I had a leak somewhere around the back of the intake manifold, which i apparently fixed with a bottle of sealant i put in with coolant. The car also gets hot if i dont run the heater. In addition to that, when i turn off my heater/AC, you can hear a constant hissing sound right behind the vents in the center of the dash. WTF??

SOURCE: Coolant leak on top of intake manifold

It is Threaded and you can Use Epoxy or even Gas Line Sealing Tape to seal the Pipe. Please Rate My Response! Thanks!

SOURCE: Hose from water pump to intake manifold above and behind water pu

this is a water pump bypass hose connector to the manifold, take the broken piece to a parts store and show it to them, it should have the threads still broken off in the manifold so explain that. To remove the broken piece ask for a EZ OUT to fit the piece you took to the store.
It is common for these to become brittle and break off but it is a simple fix.

SOURCE: intake manifold sealant repair now leaking maybe oil? coolant b4

You need to remove the thermostat housing again. Then you will have to extract the bolts you broke off. You will need to drill and tap them so you can use an easy out to remove the broken bolts from the threads. Then you can clean up both mating surfaces and replace the gasket and the thermostat. Check to make sure you did not crack the thermostat housing or you may have another leak when finished. They are usually aluminum and break easily if too much pressure is applied or they are corroded and weak.

SOURCE: 2002 Mitsubishi Galant gets poor acceleration.

LOOK AROUND THE AIR INTAKE HOSE.MAKE SURE IT IS INTACT NOT LOOSE.CHECK ALL VACUUM HOSES ON INTAKE.MAKE SURE THEY ARE IN PLACE.

SOURCE: smoke from exhaust

Sorry mate it sounds like the head gasket has gone. With no smoke, yes the inlet manifold, plus you will smell exhaustgas in the car,