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Broken radiator drain plug

Radiator drain plug broke. Most of it came out but a small piece was stuck. When I tried to get it out, I think I pushed it back up inside the radiator. Got the new plug on & seems to be o.k. but wondering if there is a piece still inside the radiator if it will cause major problems to just leave it. It’s a very small plastic piece.

I wouldn’t worry about it. That little piece of plastic is going sit at the bottom of the radiator without doing any harm.


I disagree. That little piece of plastic can jam in your water pump and cause all kinds of damage. Flush it out using the following procedure:

  1. Disconnect your lower radiator hose from the bottom of the radiator and put a bucket below the hose to catch the fluid.
  2. Turn your heater to full heat.
  3. Take a garden hose, and gently add water to the radiator.
  4. Watch the hose so that you know that you flushed the red plastic piece out.
  5. Re-install radiator hose after all water has drained, and add 50% straight antifreeze and 50% DISTILLED water.
  6. Fill up overflow bottle with straight antifreeze.
  7. Drive knowing that you will not screw up your thermostat or water pump!!

Good luck,


  1. Watch

Is that drain plug on the same side as the lower radiator hose, or the opposite side? If it is on the opposite side, it’s not going anywhere. It’ll never cross to the other side of the radiator, and I’d follow tester’s advise. If it is on the same side, I’d worry about it. The best way to get it out would be to pull the radiator out, and flush with clean water with the radiator tilted so that the lower radiator hose bib was down, and repeatedly flush until the piece falls out.

However, most cars have the drain plug on the opposite side than the lower radiator hose, so I wouldn’t worry about it.