You don't drain the radiator from the cap.
At the bottom of the radiator (Sometimes on both sides), you'll find what's called a "Petcock". This is a plug that you unscrew to drain the radiator.
Unscrew either one, and remember, when reinstalling, be careful not to cross-thread the plug or tighten it too much. This will damage the threads in the radiator and ruin the entire unit.
Also, once you've drained your radiator, you might as well flush it also.
Start the engine and turn on the heater to "Max Heat, a/c off" Disconnect the upper radiator hose and insert a garden hose. Flush until the water is clear. If there's any blockage, take it into a shop so it could be "Acid flushed".
***NOTE***
Don't run your engine longer that 1-2 minutes during this procedure.
Mar 10, 2010 at 7:36 AM
