Repair Radiator Hose: How to Replace a Radiator Hose Adaptor

Radiator hose with clamps
  • 1-3 hours
  • Intermediate
  • 0-50
What You'll Need
Drain pan
Straight slot screwdriver or 5/16 inch nut driver
What You'll Need
Drain pan
Straight slot screwdriver or 5/16 inch nut driver

Sometimes when you need to repair a radiator hose, all you need to do is cut it at the point of the leak and insert an adapter or splice. Also, some cooling system flush and cleaning kits require an adapter to be put in the middle of either one of the radiator hoses or one of the heater hoses. This adapter is used to inject cleaning fluid into the cooling system while the engine is running and also to attach a hose for fresh water, which is used to flush as much rust and contamination as possible out of the cooling system.

Step 1 - Drain Off Coolant

Place the drain pan under the radiator drain and open the drain. If you’re changing an adapter on the upper radiator hose you only need to drain off enough coolant to clear the upper radiator hose opening. If you’re changing an adapter on the lower radiator hose, you’ll need to completely drain the radiator.

Step 2 - Loosen the Clamps

car engine

On every adapter there will be two clamps. Loosen both of them until they slide freely down the hose away from the adapter.

Step 3 - Remove Leaking Adapter

Using a twisting motion, remove the adapter from the hose ends by pulling them apart. Sliding a screwdriver between the hose and adapter and twisting will help break the seal between the two.

Step 4 - Insert New Adapter

Using the same twisting motion, slide the new adapter into the two hose ends and push until the hose hits the stop on either side.

Step 5 - Tighten the Clamps

Slide the two hose clamps back up until they sit halfway along the length of the adapter on both sides. Using your desired tool, re-tighten the clamps sufficiently to preclude any leakage.

Step 6 - Refill the Radiator

adding coolant to a radiator

Close the radiator drain valve, also known as the petcock valve. If the coolant you drained was relatively new and clean, it can be reused. Otherwise refill the radiator with the dilution ratio recommended by your car’s manufacturer.

Step 7 - Check for Leaks

Once the radiator is refilled, start the engine. Let the engine run as you recheck the radiator level and add coolant as necessary. Once the radiator is filled, put the cap back on and allow the engine to run for about 15 minutes to come to temperature and pressure as you carefully check all over for leaks, paying special attention to your repair of the radiator hose adapter. Tighten the hose clamps as required to make sure they won’t leak.

Above you have been given seven steps and two tools to repair a radiator hose adapter.