1996 Chevrolet Silverado add cooling

You need to pressure test the cooling system to find any leaks.I don't think it's possible for the intake to leak into cylinder #5. The coolant ports are at the end of the heads so they wouldn't be adjacent to #5.

what kind of tool I need to use to pressure test the cooling system?

A cooling system pressure tester. You might be able to rent/borrow one at the auto parts store.

I pressure test the cooling system and i found a leak on the right side of the radiator the radiator look like it is plastic can it be fix are do i need to buy a new radiator? it like a split about 2" long i don't see a release valve on the pressure tester to release the pressure so i screw the tester of the radiator but the gauge didn't go back to zero it is set on about 3 psi why? can i check for Intake manifold gasket leak with this pressure tester?

You can't repair those plastic radiators. Nothing will hold. You have to replace the radiator. Once you replace the radiator you can pressure test again to see if there are any more leaks.

do this 1996 Chevrolet Silverado 5.7L V8 2WD Automatic have a engine Cooler on it if it does what do it look like and located? the auto part store want to know.

The engine cooler is the radiator itself but I think you are asking about an engine oil cooler. If it does there will be 2 large oil lines going into the radiator that run back to the engine.

Those line will be in addition to and larger than the trans cooler lines, assuming it's an auto trans.

I replace a new radiator and press test the cooling system so now I see a little leak coming from the front of the lower intake manifold gasket running down how do I fix it? what is the radiator cap rating psi?

You remove the intake manifold and replace the gasket. There is no other way to seal an intake leak. You have to be very careful when removing the distributor also because it will require a professional level scan tool to set the proper position when re-installed.

I was thinking I could apply a paint mark on the edge of the distributor body directly below the rotor tip and mark the position of the distributor base to the engine to ensure the distributor can be re-installed in exactly the same position as originally installed?

Yes, that is exactly what you need to do. Just make sure the engine isn't moved while it is out.