Updated on Aug. 22, 2024
Properly tightening fasteners saves money and lives by preventing loose car parts from failing. Most of the time, you can do this yourself.
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Sometimes it’s a rattle, or maybe a loud thud. Keeping parts securely tightened and bolted together lessens the possibility of premature part wear and failure, reduces overall vehicle operating expenses and makes driving more fun.
Once a nut or bolt becomes loose, it can quickly become unfastened. Failures due to loose parts can have nasty consequences. If you hear noises when accelerating, stopping, turning or driving over a pothole, it usually means one of the 30,000 or so parts in your car is loose.
Although modern cars can be held together with adhesives, plastic rivets, or speed nuts, the humble nut and bolt still make up the majority of fasteners.
Fasteners may loosen due to:
Pinpointing a loose fastener can be tricky, but it’s worth the time and effort. Look for these telltale signs that indicate loose parts:
Every bolt type and grade has a specific torque specification (spec). If using a torque wrench to tighten loose fasteners, torque to 50% of spec, then to 100%. So if a bolt’s tightening torque is rated 150 foot-pounds (ft-lb), first torque all bolts to 75 ft-lb, then 150 ft-lb.
Performing a DIY “safety tightening” as part of your annual maintenance schedule can eliminate rattles and noises plus identify potential problems, avoiding a costly crisis before it starts.
You’ll need a 1/4-in., 3/8-in. and 1/2-in. drive standard and metric socket set (use six-point sockets if you have them), safety glasses and gloves, as well as a floor jack and safety stands. Box-end wrenches also work well, but you cannot measure torque.
Do not use an open-end wrench for final tightening. Its weaker jaws can spread open, rounding off a bolt head or slip off, causing an injury. Make sure the socket or wrench head fits fully and snugly on the nut or bolt head.
Here’s what to do if a part becomes loose:
The following simple DIY repairs can save you from replacing parts costing hundreds of dollars. P.S. Here’s why using certain automotive fasteners is a no-go.
Remove any rust from exposed threads. Loosen, then retighten lugs, nuts or bolts in a star or cross-cross pattern to spec, using a torque wrench or digital torque adapter. Always replace rusty or rounded lug nuts and bolts; never try to rethread or restore damaged wheel studs or lug nuts and bolts.
Loose wheel hub bearing nuts can cause the steering wheel to shake at low to medium driving speeds. If the hub nuts are loose, tighten, then replace with new, usually 30 millimeters or larger. Many parts stores lend tools if you don’t have this size socket in your toolbox.
Loose disc brake mounting hardware can cause rattling while driving over bumps or potholes.
Safely jack up your car and remove the wheels. Inspect the disc brake caliper mounting bolts (usually in a bracket behind the rotor) for visibly loose or worn parts. Loose brake hardware can cause brake pads and rotors to wear unevenly or the steering wheel to vibrate while stopping. Save $100 or more if you properly lube, clean and tighten brake hardware
Loose suspension hardware or fasteners can cause a sharp snapping or crack when driving or turning. It may also cause uneven tire wear or vibrations when stopping. With the wheels off, inspect and tighten:
Metallic clanking, rattling or vibrations from under your car on acceleration indicate a misaligned exhaust system caused by a loose muffler clamp or mounting bracket/hanger.
When the exhaust is cool, grab and shake the tailpipe. It’s normal for an exhaust system to move slightly. Listen for parts knocking into each other, especially the tinny sounds given off by a loose heat shield.
Working safely and wearing eye protection, carefully spray fasteners with rust penetrant. Using six-point sockets, tighten all muffler clamps, mounting brackets and heat shield nuts and bolts. Replacing broken or rotted muffler clamps, exhaust hangers or insulators yourself can save $50 to $100 in parts and labor.
A loose exhaust system can cause muffler or catalytic converter failures. Replacing those are best left to your mechanic.
Rattling or squeaking from under the hood can be caused by loose battery hold down bolts, engine support bolts or component mounting bracket fasteners.
A bouncing battery will short-circuit, greatly shortening its life expectancy. Depending on the battery’s location, the terminals can short-circuit against the underside of the hood or the seat cushion support springs. The latter can cause a fire.
Check the telltale signs listed above and check that all mounting brackets, pulleys, tensioners and idler wheels are secured tightly to the engine. Also check for a loose fender radiator support, hood and hood latch, and bumper support fasteners.
Gently snug loose valve cover and engine oil pan bolts if you notice oil stains around them, not puddles of oil. Taking a half-hour to tighten every nut and bolt you can see and reach under the hood can potentially can save you hundreds, if not thousands of dollars, while reducing breakdowns.
If spark plugs work their way loose, they sound like an exhaust leak. They can blow right out of the cylinder head, taking the threads with them. Over-tightening can distort the plug or cylinder head threads, making it virtually impossible to remove without damaging the head. You can save money by correctly replacing spark plugs yourself.
A loose seat track that’s rocking back and forth, or a door that won’t stay latched properly, are extremely dangerous. A seat track not firmly anchored to the frame and/or floor can cause a driver’s foot to come off the brake pedal when trying to stop. Check all seat-attaching bolts, especially if you feel any movement in the seat.
A loose door latch or striker can cause a door to pop open and eject an occupant during an accident, especially if they’re not wearing a seat belt. Tightening both are simple 15-minute DIY repairs that save you from replacing difficult-to-install, pricey door latches ($100 to $300), or having plates welded to the floorboards if the seat bolt threads rip out. Most of all, it can save lives.
