I just ran into this problem. The petcock is plastic and has a metal pin protruding thru the side. This pin rides in a "track" and locks the petcock into place when you put it back in. I broke the pin removing the petcock and had to remove the radiator to repair it. You may be able to do this with the radiator in place. See if you can feel the track and if you replace the pin, you will feel it lock into place when you reinstall the petcock. The pin can only protrude on one side of the petcock so that the petcock will seat correctly. Good luck.
On the back of the radiator, driver side.
out the petcock on the back side of the radiator
The petcock is on the right side of the radiator(drivers side). It is not in the back of the radiator, it is on the side underneath all the shrouding. Cannot see it unless you do remove the plastic shroud. Also it is plastic and on mine removed easily to drain water.
I have a 2000 Pontiac Grand AM and radiator drain cock is located at the lower/front (not bottom) at the curbside of the radiator, you will need a hex key to back out petcock.
there may not be one if there is is it on the bottom side and if it is not you candrain it by removing the bottom rad hose The 1999 Pontiac Grand Am does not have a radiator drain valve. To drain the radiator, remove the lower radiator hose. The engine should be cold and the water fill cap removed for venting. I have a 2000 Pontiac Grand AM and radiator drain cock is located at the lower/front (not bottom) at the curbside of the radiator, you will need a hex key to back out petcock. .
at the back of the engine
Replace petcock with a properly sized plug Be sure you turned the petcock back in all the way. Try opening and re-closing petcock,may be some trash in it.On mine you have to push in on the petcock and turn it to re-seat it.
I'm assuming you're trying to drain the radiator? Look up through the front wheel well on the passenger side. You'll see it on the back of the radiator.
Remove the wiring harness from the back of your 1999 Cadillac Escalade radiator fan motor. Remove the radiator fan motor retaining bolts. The radiator fan will come off.
On my 1992 Saturn the radiator petcock is above the splash guard on the bottom of the radiator on the side closest to the belt. You may want to drain the radiator via the lower hose. The petcock on my Saturn came apart. The retaining clip came off of the back. I did not force it and according to the Saturn forums this happens. I am now trying to see if it can be repaired or replaced and much farther than I wanted to be from completing a quick water pump change.
remove the splash guard on the bottom, and it will be on the drivers side of the car, by the side of the radiator facing the back of the car, just past the left most part of the radiator, undo from the bottom of the car, even though it is NOT visable from the bottom.
According to the Haynes manual, the thermostat is located by follwing the lower radiator hase from the radiator back to the engine. The housing for the thermostat is bolted on the side of the engine block facing the radiator.