How to Repair Plastic Auto Parts

by Hugh Patterson
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gear . part of car. sign.thank you for not smoking image by L. Shat from

A large percentage of auto parts are made from plastics such as ABS. Plastic is inexpensive and easy to form into a variety of parts. The majority of a car’s interior is made from plastic, specifically ABS. Over time, even strong plastics can break due to daily stress. Replacing these parts can be expensive and if the car is older, the parts can be difficult to locate. Use acrylic solvent cement and a few common household items to repair plastic auto parts.

Step 1

Clean the part to be repaired thoroughly, as solvent cement works only if the material is free of grease and dirt. Mix concentrated liquid laundry detergent and hot water together, using a ratio of four teaspoons of detergent to 16 ounces of water. Use a toothbrush to clean any dirt or grease from the surface of the part. Scrub the cracked or broken edges of the part as well. Dry the part completely.

Step 2

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Fit the broken pieces together to make sure there is no gap between them. Use gap-filling cement if there is a small gap between the pieces when they are put together. Or, use acrylic solvent cement if the broken pieces fit together without a noticeable seam. Both types of cement use the same chemical solvent to fuse the plastic together; however, gap-filling cement is syrupy thick, while solvent cement is watery.

Step 3

Fill the squeeze bottle applicator to the halfway point with acrylic solvent cement. Use the thumb and index finger to squeeze the bottle until the cement is near the bottle’s top. Slightly release the pressure so that a vacuum is formed, which will keep the cement from spilling when the bottle is tilted during the repair process.

Step 4

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Apply a thin bead of either acrylic solvent cement or acrylic gap-filling cement to one side of the broken part.

Step 5

Fit the piece without cement applied to it onto the cemented piece. Use painter’s masking tape to hold the parts in place. Allow at least an hour to dry before handling the part. If there is a visible gap along the repaired break or crack, apply a thin bead of gap-filling cement to both sides of the part if possible.

Step 6

Scrape off any residual cement with a utility knife. Gap-filling cement will come off easily in areas where it has not fused to the plastic. Allow 24 hours curing time before putting the part back in place.

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