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How Do I Fix Torn Plastic Around Mounting Bolts On Tonneau Cover?

A tonneau cover is an excellent way to protect the cargo bed of your pickup truck. But like any frequently-used truck accessory, tonneau covers can become damaged over time. One of the most common problems is torn plastic around the mounting bolts. Thankfully, with the right materials and some mechanical know-how, you can easily repair torn plastic on your tonneau cover.

What Causes the Plastic to Tear Around the Mounting Bolts?

The mounting bolts on a tonneau cover hold the cover tightly against the bed rails of the truck. So whenever you open or close the cover, the plastic has to flex around these fixed points. Over time, this repeated movement can cause the plastic to weaken and eventually tear.

Factors That Can Accelerate Tearing

There are a few things that can make a tonneau cover more prone to tearing around the mounting bolts:

  • Cheap plastic material – Covers made with thin, low-quality plastic are more likely to tear than ones made with durable polymers.
  • Improper installation – If the cover is installed incorrectly and the mounting bolts are over-tightened, it can create stress points in the plastic.
  • Extreme weather – Exposure to very hot or very cold temperatures can make the plastic more brittle and easier to crack.
  • Not enough lubrication – Lack of lubrication around the hinges and mounting points increases friction, which accelerates wear and tear.
  • Frequent opening/closing – The more often you open and close the cover, the quicker the plastic will fatigue around the bolts.

How to Assess the Damage

Before attempting any repairs, you need to fully assess the extent of the damage:

  • Inspect the entire cover – Look for any cracks or tears emanating from the mounting bolts. Also check the underside.
  • Check the bolts – Are they loose, broken, or corroded? Damaged bolts should be replaced.
  • Test the hinges – Do the hinges move smoothly? Any squeaking or stiffness indicates a problem.
  • Try opening/closing the cover – Does it move properly or is the tear causing it to catch or bind?
  • Determine if the tear is repairable – Small cracks and surface tears can usually be fixed, but deep rips or splits may require replacing the entire panel.

Removing Broken Parts from the Tonneau Cover

If your inspection revealed any broken clamps, bolts, rivets, or other components, you will need to remove them before attempting repairs:

  • Break loose any stuck bolts – Soak with penetrating oil, then gently work them back and forth with pliers to break the corrosion free.
  • Cut away broken clamps – Use a rotary tool or hacksaw blade to carefully cut through damaged clamps.
  • Drill out sheared bolts – Use a drill bit slightly larger than the bolt shaft to drill it out.
  • Remove broken rivets – Use a rivet extractor tool, or drill each rivet head off and punch out the remains.
  • Take notes as you remove parts – So you know exactly how to reinstall them later.
  • Inspect mounting holes – Make sure the threads are intact and holes are clear of debris.
  • Clean mounting surfaces – Remove rust and old sealant; sand paint if necessary for good adhesion.

Repairing the Torn Plastic

Once you’ve prepped the area, you can move on to repairing the torn plastic itself. Here are a few methods:

Adhesives

For small cracks and surface tears, a plastic bonder or adhesive can effectively repair the damage:

  • Clean the area – Wipe away dirt and residue with isopropyl alcohol for maximum adhesion.
  • Apply adhesive sparingly – Just use enough to fill the tear; avoid getting glue on unaffected areas.
  • Clamp tightly – Use spring clamps to hold the tear closed while the adhesive cures.
  • Allow proper cure time – Most plastic bonders need 24 hours to fully cure.
  • Sand away excess – Once cured, gently sand any oozed out adhesive flush with the panel.

Plastic Welding

For longer tears, plastic welding is a more durable repair technique:

  • Trim any loose flaps – Cut away loose pieces of plastic so the tear edges are clean and even.
  • V-groove the tear – Use a rotary tool to cut a small “V” along each side of the tear. This creates more surface area.
  • Pre-weld with hot air – Soften the plastic with a hot air welder, then press the tear together.
  • Weld the seam – Run a plastic welding rod along the V-groove while applying hot air. Fuse the rod into the plastic.
  • Smooth the weld – Once cool, sand the weld seam smooth and refinish the surrounding area.

Patch Panels

If the damage is too extensive for adhesive or welding, you may need to fabricate and install a patch panel:

  • Measure and cut your patch – Trace the damaged area on cardboard, transfer to your repair plastic, and cut out.
  • Shape as needed – Use snips, shears, and a rotary tool to shape the patch to match the curves and contours.
  • Clean and scuff the surfaces – For maximum weld strength, lightly abrade the surfaces that will contact the patch.
  • Weld the patch in place – Tack weld one edge, then work along the seam, heating and fusing the plastic together.
  • Reinforce vital spots – Put extra welds around bolt holes and high-stress areas.
  • Fill edges and finish – Melt rod into the seam edges, then smooth everything flush. Paint or finish the patch to match the cover.

Replacing Broken Parts

Once you’ve repaired the torn plastic, you can move on to replacing any damaged mounting hardware:

Bolts

  • New bolts are often included – Many tonneau cover manufacturers include replacement bolt kits.
  • Use the proper bolt size – Measure your originals and get the exact same thread pitch and diameter.
  • Stainless steel recommended – For longevity. Make sure the grade matches OEM hardness.
  • Use lock washers – They prevent loosening from vibration.Split-ring washers provide the most hold.
  • Don’t overtighten – Snug down the bolts just until the lock washers flatten.

Clamps

  • Measure correctly – Improper clamp sizing will prevent a tight seal.
  • Stick with OEM style – For best fit and performance. Upgrade to heavier duty if desired.
  • Lubricate threads – Prevents galling and seizing when tightening. Anti-seize compound recommended.
  • Position carefully – Misalignment can warp the cover and cause leaks.
  • Tighten in sequence – Incrementally tighten opposing clamps for even compression.

Rivets

  • Drill out old rivets – Use a bit slightly larger than rivet’s inner diameter.
  • Clean holes thoroughly – Remove any burrs or debris.
  • Grip length is key – Too short and rivets won’t hold; too long and they bottom out before seating.
  • Use a backing plate – Helps conform the rivet tail and fills gaps.
  • Go slow when bucking – Let the hammer do the work of upsetting the rivet. Don’t strike too hard.
  • Stagger rows – Offset each row so rivets don’t line up and weaken the panel.

Reinstalling the Tonneau Cover

The last step is to reinstall your repaired or replaced tonneau cover:

  • Inspect bed rails – Make sure they are straight, clean, and rust-free. Repair if needed.
  • Add sealant – Run a bead of weatherstrip adhesive or silicone along the bed rail flanges.
  • Position cover carefully – Line up hinge holes and have helpers lift the cover into place.
  • Install hinge hardware – Hand tighten first, then torque bolts to spec starting from the center and working outward.
  • Attach support bows – If equipped, span the bows and attach to the cab end first using clamps or bolts.
  • Secure cover – Working opposite corners, tighten the clamps or bolts until the cover is evenly seated against the sealant.
  • Test operation – Open and close the cover multiple times to ensure smooth function. Adjust as needed.
  • Add lubricant – Finally, lubricate hinges and clamps per manufacturer directions to prevent premature wear.

With a little time and effort, you can make lasting repairs to torn plastic around the mounting bolts on your tonneau cover. Just take it slow, use the proper materials, and refer to the steps above. Your cover will be restored to like-new condition.

Frequently Asked Questions About Repairing Tonneau Covers

What type of adhesive should I use?

For plastic tonneau covers, look for a flexible urethane or epoxy adhesive formulated specifically for bonding plastic. Avoid super glue, hot glue, or rigid epoxies.

Can I just cover small cracks with duct tape?

Duct tape is meant for temporary repairs only. For cracks and tears in tonneau covers, it won’t last long before peeling and letting in moisture. Use a proper adhesive or plastic weld for permanent repairs.

How do I remove a broken bolt from the cover?

If the bolt head is intact, use locking pliers or a vice grip wrench to turn it counterclockwise. If the head is broken off, you’ll need to use a bolt extractor tool. Applying heat to the bolt can also help loosen the threads.

What’s the best way to drill out broken rivets?

Use a drill bit slightly wider than the rivet’s center hole. Drill slowly through the head to avoid damaging the surrounding plastic. Press hard with the drill to keep it centered and prevent walking.

Is it possible to weld plastic with a soldering iron?

Technically yes, but you won’t get good results. A soldering iron can melt plastic, but doesn’t generate enough heat for proper fusion welding. Invest in a hot air plastic welder for any major tonneau cover repairs.

How can I prevent rivets and bolts from corroding?

Use stainless steel hardware whenever possible. Apply dielectric grease to the threads during installation. Consider plastic push-in rivets instead of metal ones. And check your tonneau yearly, replacing any corroded bolts right away.

Can I just use silicon to reseal the cover if it leaks?

Silicone sealant is not enough to stop leaks on its own. You need to thoroughly clean the mounting surfaces, make any necessary repairs, and use automotive weatherstrip adhesive when reinstalling the cover. Silicone can then supplement the adhesive.

What’s the best way to lift a heavy cover onto the truck bed?

Enlist an extra set of hands. Carefully lift from the edges and set the cover on blocks on the tailgate when needed. Use moving straps underneath to carry long vinyl covers. And be sure to line up the holes before lowering into place.

How tight should the mounting bolts be?

Over-tightening can warp the cover panel or strip the bolt threads. Snug the bolts down until the lock washers flatten and the cover is held firmly against the sealant. Then tighten each bolt incrementally to the manufacturer’s spec, usually around 10-15 ft-lbs torque.

Wrapping Up

Repairing torn plastic around the mounting bolts on your tonneau cover is totally doable with minimal tools and skills. Just take your time, assess the type and extent of damage, and use the proper repair method. With a little TLC and elbow grease, you can have your cover looking and functioning like new again.

Meghan Drummond
Meghan Drummond

Meghan has owned trucks for over 20 years and installed her first tonneau cover back in 2005. She has tested over 50 different tonneau cover models hands-on. Meghan has a journalism degree from the University of Florida and previously worked as an auto writer.

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