What Causes a Radiator to Leak?

leaky radiator, what causes a radiator to leakA leaky radiator usually means a face full of steam when you open your hood and probably a ride from your friendly neighborhood tow truck.  In the good old days when radiators were made entirely from copper small leaks could spring up that were annoying but wouldn’t leave you stranded.  Today’s thin aluminum radiators with plastic end tanks often aren’t as kind to drivers and often leave you stranded with a mess and no coolant in your engine.

To find out what causes a radiator leak, the only thing we need to do is examine the operating environment of your vehicle:

What Causes a Radiator Leak:

  1. Temperature swings
  2. Rocks
  3. Accidents
  4. Radiator Fans
  5. Dirty Coolant

Temperature swings

Your radiator has to be able to function both at ambient temperature, which can be really cold depending on where you live, to over 200 degrees!  These drastic swings cause lots of thermal stress on the metal and plastic in the radiator and can cause leaks over time regardless of how well you care for your vehicle.


Your radiator is at the front of your vehicle protected only by your vehicle’s grill.  Rocks and road debris can easily find their way in through the grill and poke holes in your radiator tube and fin matrix.  These leaks are often slow and will cause drips at the front of your vehicle. Small leaks like this can easily be fixed using BlueDevil Radiator and Block Sealer.


Fender benders regularly cause radiator leaks since your radiator is at the front of your vehicle.  Anything that pushes on the front on your vehicle has the chance to either contact the radiator or bend the radiator core support causing leaks in the radiator or in the coolant hoses going to a from it.  If you’ve been in an accident make sure your frame is straight before attempting to repair your radiator.

Radiator Fans

Radiator fans can cause a radiator leak in 2 different ways.  If your radiator fan doesn’t turn on it can cause high temperatures and pressures in your system leading to a leak.  On the other hand, if your radiator fan is spinning but has a bad bearing the wobbly fan can contact your radiator damaging the tubes and causing a leak.

Dirty Coolant

Dirty coolant can cause a radiator leak due to corrosion.  If your coolant is dirty or of the wrong type it can cause pitting in the aluminum in your radiator and cylinder head.  Since your radiator is made of thin metal small pits in the aluminum can lead to leaks. Make sure to regularly flush your radiator to ensure your coolant is not damaging your radiator.

What causes a radiator to leak doesn’t change how you fix the leak.  If a new radiator is too expensive of a repair for you or your vehicle, consider using BlueDevil Radiator and Block Sealer!

You can find BlueDevil Radiator and Block Sealer, you can find it at one of your local auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto Parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributor
  • DYK Automotive
  • Fisher Auto Parts stores
  • Auto Plus Auto Parts stores
  • Hovis Auto & Truck Supply stores
  • Salvo Auto Parts
  • Advantage Auto Stores
  • Genuine Auto Parts stores
  • Bond Auto Parts stores
  • Tidewater Fleet Supply
  • Bumper to Bumper Auto Parts
  • Any Part Auto Parts
  • Consumer Auto Parts

Pictures Provided By:

leaky_radiator.jpg – By Superfroyd – Licensed by Getty Images – Orginal Link