How to Repair a Cracked Plastic Radiator Inlet

by Zyon Silket

Over time, due to constant heating and cooling cycles, the plastic parts of a radiator may become brittle and even crack. Replacing a radiator that has a cracked inlet tube is not necessary if you prefer to repair the crack. Although a repaired crack may not give you the same longevity of a new radiator, it will buy you a lot of time before the radiator must be replaced.


Remove the upper radiator hose form the radiator inlet tube, squeezing the compression tabs together on the radiator clamp. This releases the pressure on the hose. Pull the hose off the inlet tube. If the lower inlet tube is cracked, first drain the radiator fluid by placing a drain pan under the petcock on the bottom of the radiator. Open the petcock and let the fluid drain.


Sand the inlet tube with 600-grit sandpaper to give the epoxy a surface to adhere to. Sand approximately 1 inch around the crack to allow enough room for the epoxy.


Mix the two-part plastic epoxy together. The epoxy must have a heat rating of 300 degrees Fahrenheit or higher to withstand the heat of the radiator fluid.


Separate the crack as far as possible without increasing the length of the crack to allow the epoxy to get into the crack. Smear a moderate amount of epoxy around the crack, inside and outside the inlet tube. Allow the epoxy adequate time to cure. Follow the recommendations printed on the epoxy packaging.


Sand the epoxy smooth with 600-grit sandpaper. A small bump of epoxy should be present when the sanding is completed, but all rough edges and steps between the epoxy and the plastic must be smoothed out to prevent leaking.


Remove the OEM radiator hose clamp from the radiator hose and replace it with a cam-style band clamp. This style clamp has a larger clamping surface and you can control the amount of pressure needed to seal the hose against the inlet tube.


Push the radiator hose back onto the inlet tube and slide the band clamp as far onto the inlet tube as possible. Try to get between the crack and the wall of the radiator. The less pressure you apply to the repaired crack, the longer the repair will last.

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About the Author

Since 2006 Zyon Silket has been writing for companies such as SEOWhat, L&C Freelancing and T-Mobile Wireless. He has extensive experience working in supervisory roles within the wireless and Internet technologies fields. Silket is pursuing a Bachelor of Arts in business management and network technologies at Lehigh Carbon Community College.