How Long Does a Radiator Drain Cock Last?

Your car’s coolant system is one of the most critical on the entire vehicle. Without it, the engine would quickly overheat, causing devastating damage. Coolant is cycled from the radiator, through the hoses, past the thermostat, and around the engine. While it cycles, it absorbs heat, and then transports it back to the radiator, where it is dissipated with moving air.

Coolant is designed to absorb heat and also withstand freezing temperatures. This is what allows you to run your engine during the winter, when regular water would freeze solid. However, coolant has a finite lifespan and you should have it drained and filled once every five years or so.

Obviously, there has to be a way to get the old coolant out of the system before you can add new coolant. That’s what the radiator drain cock does. It’s a small plastic plug located at the bottom of the radiator. It screws into the radiator’s base, and allows the coolant to be drained out. Once the old coolant is out, the drain cock is replaced and new coolant is added.

The problem here is that the drain cock is made of plastic, which is pretty easy to damage if you’re not careful threading it back in. Once the threads are stripped, the drain cock will no longer seat correctly and coolant can leak out. If the threads are badly stripped, it’s possible that the drain cock will fail completely and coolant will be allowed to flow out unchecked (particularly when the engine is hot and the radiator is pressurized). Another potential issue is if the rubber gasket on the tip of the plug is damaged (this will allow coolant to leak out).

There’s no set lifespan for a radiator drain cock, but it definitely won’t last forever. With the right care, it should last for the life of the radiator (8 to 10 years). However, it takes very little to damage it.

Because a damaged radiator drain cock is potentially very serious, you need to know the signs of failure or damage. These include:

  • Threads on the drain cock are smoothed out (stripped)
  • Head of the drain cock is damaged (making it difficult to remove)
  • Plastic is cracked from heat exposure
  • Coolant leaks under the radiator area of the car (can also indicate a leak at a hose, from the radiator itself and other areas).

Don’t leave things to chance. If you suspect your radiator drain cock is damaged or have a coolant leak, a certified mechanic can help inspect the radiator and drain cock, and replace any parts needed.


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