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How To Replace Your Heater Hoses


One one the most common sources of coolant leaks are the heater hoses. These hoses allow hot coolant to enter and leave the heater core to heat the interior of the vehicle. Over time these hoses will get hard and brittle and can crack or break. Give the hoses a feel. Hoses should not be excessively hard, brittle, soft, mushy, or swollen. If they are, replace them as soon as you can

Even if you are in doubt and they are more than four or five years old, replace them just to be safe.

Difficulty: Easy
Time Required: 30 to 60 minutes

Here's How:

  1. Place a drain pan or bucket under the radiator and drain the system by opening the petcock fitting near the bottom. If the old engine coolant is not going to be used, dispose of it immediately because it is extremely poisonous.
  2. Remove the hose clamps from your old hose with a pliers or screwdriver, depending on the type of clamp used, and twist and pull the hose to loosen it from the fitting.
  3. Remove the hose and carefully scrape the fittings clean, then apply a small amount of gasket sealer to the fittings to assure a tight seal with your new hose. Apply sealer to the fitting only; this will help avoid any excess from possibly clogging the hose or a water channel in the block.
  4. Slide the clamps onto your new hose and install them, making sure that the hose ends slide over the fittings far enough to position the clamps properly.c
  5. Tighten all the clamps, fill the radiator with coolant, and start the engine to check for cooling system leaks. Re-check the fluid level after the engine has reached normal operating temperature.


  1. When replacing your heater hoses it's a good idea to measure your old ones first - both the length you'll need, and the inside diameter. Heater hose comes in 1/2", 5/8", or 3/4" diameters, with two different sizes often being used on some cars.
  2. Replace your old hose clamps as they tend to become corroded and weak with age.
  3. Do not twist or pull the heaters hose off the heater core. There is a good chance the tubes will break requiring the heater core be replaced. Use a sharp knife or razor blade to slit the hose from the end to past the end of the tube and gently work the hose loose and remove it.
  4. I recommend using Permatex #2 as the hose sealant.
  5. CAUTION! Do not replace the hoses on a hot engine. Make sure the engine is cold before attempting this job. Failure to do so can result in serious burns or other serious injuries.

What You Need:

  • Screwdriver
  • Adjustable Pliers
  • Slip-joint Pliers
  • Hoses
  • Hose Clamps
  • Non-hardening Gasket Sealer
  • Antifreeze

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