A tonneau cover goes over the back of your pickup truck bed. It helps keep things dry inside the truck bed. But sometimes tonneau covers leak when it rains. There are a few reasons why this happens. Here are some questions and answers to help understand why your tonneau cover leaks and how to fix it.
Why does water get into my tonneau cover?
Water can get into a tonneau cover in a few ways:
- Through small holes or tears in the cover material
- Between the cover and the bed rails
- Through the hinge joints
- Around the tailgate seal
Holes or tears – Even tiny holes or tears can let water leak in. They may be too small to see. But they let rain follow a path inside.
Gaps at bed rails – Most covers have a weather strip seal along the bed rails. It seals the gap between the cover and rails. But these seals can wear out or get bumped out of place. That leaves gaps for water to drip through.
Hinge joints – Hinges connect the folding panels on soft foldable covers. They are designed to be watertight. But if a hinge gets damaged or bent, it can leave a gap for water to leak in.
Tailgate seal – All covers seal against the tailgate. But that seal can leak if it gets damaged or dislodged.
Why does my tonneau cover only leak in heavy rain?
In light rain, small leaks may not drip much water in. But hard rainfall can push more water through tiny gaps and holes. The heavy rain overwhelms seals that normally keep lighter rain out.
It’s like a dam holding back a river. A small crack won’t leak much. But when the river rises high and pushes hard, more water squeezes through that crack.
How can I find where my tonneau cover is leaking?
To find leak spots, do a water test on a dry day. Use a garden hose to spray water on the entire cover, like rain. Let it run for a few minutes.
Then open the cover and look inside with a flashlight. See if any water droplets got through. Those wet spots point to the leak locations.
You can also try this test after driving in heavy rain. Quickly check for leaks before things dry out.
How can I fix leaks around the bed rails?
If water leaks in around the bed rails, the rail seals need help. Here are some ways to fix rail seal leaks:
Add sealant in the rail channels
- Clean the rail channels so they are free of dirt and debris
- Apply silicone sealant or waterproof caulk in the channels
- Press the cover seals into the sealant to create a watertight barrier
Replace worn out rail seals
- Remove the old seals and clean the channel
- Install new rail seals made for your cover
- Apply sealant under the new seals for extra protection
Add weather strip foam
- Clean the rail channels
- Apply plumber’s pipe wrap foam in the channels
- Fold the cover seals over the foam to seal the gap
How can I fix leaks at the tailgate?
If water leaks in around the tailgate seals, try these fixes:
Adjust the tailgate seal
- Loosen the retainer clamps
- Shift the seal tighter to the tailgate
- Tighten the clamps
Add extra sealant
- Clean the sealing surfaces
- Apply silicone sealant along the tailgate seal and end flaps
- Press the seals into the sealant and let dry
Replace damaged seals
- Remove the old seals
- Install new tailgate seals made for your cover
- Seal them in place with silicone sealant
How can I fix leaks at the folding hinges?
To stop leaks at hinge joints, you need to seal the hinge gap. Try these methods:
Caulk the hinge gap
- Open the cover to expose the hinge gap
- Fill the gap with silicone sealant or caulk
- Close the cover and let the sealant dry
Add weatherstrip foam
- Clean the hinge area
- Apply self-stick foam weatherstrip cut to fit the gap
- Close the cover to seal the foam in place
Adjust or replace damaged hinges
- Inspect hinges for damage or bent parts
- Carefully adjust bent hinges to realign the joints
- Replace damaged hinges with new ones if needed
How can I find and fix holes or tears in my cover?
Small holes and tears can be tricky to find. Here are some tips:
Do a thorough inspection
- Look over the entire cover closely
- Hold it up to bright light or the sun
- Feel along seams and folds for holes
Do a water test
- Spray water on the cover like rain
- Look inside with a flashlight for water droplets
- Leaking spots point to holes or tears
Patch holes and tears
- Clean the area thoroughly
- Apply adhesive vinyl patch material from the inside
- Seal all edges of the patch
Seal small punctures
- Clean and dry the area
- Apply a liquid sealant like GE Silicone II
- Let it flow into the hole and cure
How can I prevent future tonneau cover leaks?
To help your tonneau cover seals last longer:
- Keep the cover clean to prevent seal wear from dirt
- Avoid dragging objects over the cover
- Don’t drive with heavy loads that press on the cover
- Inspect seals often and reseal gaps when needed
- Adjust and lubricate hinges per the manual
- Park in the shade to limit cover sun damage
Proper care will help your tonneau cover seals stay leak-free for many years! But if leaks happen, use these tips to find and fix the problem spots. With some diligent troubleshooting and seal repairs, you can stop those annoying rain leaks.