A tonneau cover is a useful truck bed accessory that provides protection, security, and improved gas mileage. However, tonneau covers can develop issues over time, including making whistling noises when driving at highway speeds. As an expert writer, I will explore the potential causes and solutions for a whistling tonneau cover in this detailed article.
What Causes A Tonneau Cover To Make Whistling Noises?
There are several possible reasons why your tonneau cover may be making annoying whistling noises on the highway:
Gaps Allowing Air To Pass Through
If there are any gaps where your tonneau cover meets the truck bed, wind can pass through these openings and cause whistling. This is especially common with soft roll-up covers that can develop gaps as they age. weather stripping, buy weather stripping, or seal gaps with caulk to prevent airflow.
Loose Attachment Allowing The Cover To Flap
If your tonneau is not securely attached to the bed, the cover can vibrate or flap in the wind. This allows air to flow over the cover unevenly, creating turbulence and noise. Ensure all clamps, snaps, and bolts holding the cover down are tight.
Rear Differential Noise Amplified By The Cover
Sometimes the whistling is actually rear differential noise that resonates through a solid tonneau cover. The cover acts like an amplifier, making normal drivetrain sounds seem louder. This is common with hard folding and retractable covers.
Crosswind Turbulence Over The Cover
Strong crosswinds can create eddies and turbulence as air passes over your tonneau cover. This uneven airflow results in whistling or buffeting noises. There is no good solution aside from avoiding driving in very windy conditions.
How Do You Fix A Whistling Tonneau Cover?
If your tonneau cover is the cause of whistling on the highway, here are some tips to stop the noise:
Inspect For Gaps and Re-Seal
Carefully examine where the cover contacts the bed rail and tailgate. Check for gaps or voids where air can pass through. Use weather stripping, caulk, or vinyl repair tape to seal any openings. Tighten the cover’s retention clamps for a better seal.
Adjust The Cover To Sit Flush
Over time, covers can warp or shift out of alignment. Realign the panels or canister so the cover sits flush with no edges lifted. Adjust the tension cables on soft roll-ups to create an even surface.
Add Drains To Allow Condensation To Escape
Water or condensation buildup inside a tonneau cover can lead to leaking and whistling from the airflow. Install drain tubes to give moisture an escape path. Keeping the cover interior dry will prevent leaks.
Replace Old Or Damaged Seals and Gaskets
If the cover’s rubber seals have become brittle, cracked, or ripped, they will leak air. Carefully detach the old seals and install fresh tonneau seals along the rails, tailgate, and panel edges to prevent airflow.
Secure The Cover With Added Latches or Velcro
If your cover is loose or prone to flapping, add extra securement points. Install velcro strips on soft covers to keep the vinyl tight to the rail. Add extra clamps or lockable paddle latches to firm up retractable and folding covers.
Apply Protectants To Keep Vinyl Covers Tight
Soft vinyl covers can stretch out over time, creating gaps along the sides. Apply vinyl protectant conditioners to keep the material supple, tight, and quiet. Letting vinyl dry out increases rips and noise.
Avoid Driving With The Cover Partially Open
Never drive with a folding or retractable tonneau partially opened. The unsupported panel will flap violently in the wind. Fully open or fully close the cover before driving to prevent damage or loud noise.
Have A Mechanic Inspect The Differential
If all cover gaps are sealed and it still whistles, the rear differential may be the culprit. Have a mechanic inspect the gear oil level, breather filtration, and for any worn bearings that could cause whistling.
Why Do Tonneau Covers Whistle At High Speeds?
The whistling noise from a tonneau increases in volume and frequency at higher speeds for two main reasons:
Greater Wind Flow Over The Cover
As a truck picks up speed on the highway, airflow over the tonneau greatly increases. More wind results in higher pressure and turbulence against the cover, which can push through or flap loose sections.
Resonant Frequency Is Achieved
The whistling reaches its peak volume when wind speed over the cover causes resonance. Similar to blowing over a bottle, the airflow vibrates the material at its ideal resonant frequency, amplifying the noise. This often occurs between 65-80 mph.
Tips To Prevent And Stop Tonneau Cover Whistling
Here are some pro tips from tonneau cover experts on minimizing whistling truck bed covers:
- Use thick, dense vinyl protectant creams to keep soft covers tight. Reapply every few months.
- Adjust cover tension and alignment at least twice per year to account for stretching and warping.
- Clean tonneau tracks and lubricate the plastic slides with silicone spray to prevent sticking.
- Add sealant pads under the cover rails and magnets along the tailgate edge for a tight seal.
- Use small rubber bumpers on folding panels and canister edges to damp vibrations.
- Install foam weather stripping instead of rubber seals for better sound insulation.
- Try adding aerodynamic tonneau cover tailgate spoilers to smooth airflow.
- Replace old factory seals with thicker aftermarket seals to prevent leaking and noise.
- For hard covers, add dense sound dampening mats on the underside to mute resonances.
FAQ About Noisy Tonneau Covers
Why does my soft roll up tonneau whistle so loudly on the freeway?
Soft vinyl covers can stretch over time and develop gaps at the sides and tailgate. The wind passing through these openings creates loud whistling. Try re-tensioning the bows and using vinyl protectant.
Will adding sealant strips completely prevent my cover from whistling?
Extra sealing can help but is not a 100% fix for a noisy cover. The wind flowing over the cover surface can still cause some whistling due to turbulence. Proper cover alignment and tensioning is key.
Can I drive with my hard folding cover partially opened?
Never drive with a folding cover partially opened. The panels will flap violently and damage the hinges or your truck bed. Fully open or fully close it before driving.
Does a tonneau cover whistle more with it empty or loaded?
An empty bed allows more airflow under the cover, potentially increasing whistling from below. A loaded bed blocks this airflow but causes more buffeting on top. Both can make noise.
Should I grease the tonneau hinges to reduce noise?
Yes, lubricating the hinge bushings and pivot points allows the panels to move smoothly and quietly without squeaking. Use silicone or PTFE spray lube for best results.
The Bottom Line On Tonneau Cover Whistling
Annoying tonneau cover whistling usually results from airflow through gaps or loosely secured panels flapping at speed. Thoroughly inspect for leaks, adjust cover fitment, lubricate components, and reseal the tailgate and side rails to quiet it down. Hard covers may amplify standard differential noise. Proper care and maintenance will minimize whistling and keep your cover secure.