Which way to drain?

[OJLane]

Hi all, stupid question but I’ve just put a new to me used radiator in my car, unfortunately it doesn’t seem to drain the coolant from the drain hole in either position and I don’t want it to suddenly break free when it gets up to pressure and I’m driving and empty the coolant. Which position is to lock and which is to drain? I’ve tried to put some water in my old radiator to test but that won’t drain in either position either.

 

[Tonye]

I think it screws all the way out pal

 

[MrGreedy]

The way you're looking at the photo, it's a normal thread. Anti clockwise to undo, clock wise to do up.

Does it turn at all?

Usually with Mercs, either the valve (petcock?) will turn 90 degrees to unscrew and the you pull out towards you to get the coolant to drain, or once at 90 degrees you pull out slightly and continue to turn to 180 degrees to get the coolant to drain.

Doing up is obviously reverse, you might need to push in slightly at the 90 degree mark to get the valve to turn the last 90 degrees.

 

[Justintyme]

Some of them will start draining when the plug is loosened, some have to be completely removed, and some will have a "double" thread, ie; first sectioned threaded, then middle section blanked, no threads and then 3rd section again with threads. Regardless of which type you have, once its completely out, it has to drain.....unless of course its blocked? For it to drain of course, the header tank cap must be removed to allow air in to prevent it air locking and preventing the water to drain.

 

[TeddyRuxpin]

Anti-clockwise. Mine was just very stiff and felt like it was going to break, but it didn’t (used needle nose pliers). There’s no need to remove it completely, a quarter to half turn is enough for it to drain

 

[Tonye]

OR, take the bottom hose off

 

[OneForTheRoad]

Left for loosie , right for tighty.