i just flushed my radiator. its in a fairly obvious place on the rear of the radiator(side facing the engine), look up from the ground, about 4 inches from the bottom on the rear almost center. the 5/8" (i think) bolt protrudes about an inch out be very careful no release the pressure from the system first
The 1991 Pontiac Grand Am radiator drain plug can be found on the bottom of the radiator. The radiator drain plug will be in the center of the radiator bottom.
In between the bumper and the frame, on the passenger side.
If it is mechanical the diaphragm has a hole in it.
I have a 92 b2200 with 325k miles. Ibought it brand new.
You can find the 1991 Buick Skylark radiator drain plug on the bottom of the radiator. The radiator drain plug will be in the center of the radiator bottom.
The radiator drain plug is on the bottom edge of the 1991 Legend. It looks like a wing nut and is on the drivers side.
Bottom of radiator
It's in the fuel tank. You have to get access to the top of the fuel tank
follow the upper radiator hose
The horn is located on the passenger side of the radiator support behind the bumper. The horn relay is located on the passenger side fenderwell. I've attached some links below for future reference.
Look under vehicle follow fuel line from tank