Water in Trunk Under Spare Tire Symptoms (Find the Leak)

Finding water under your spare tire is a nasty surprise. It leads to rust and a rotten smell fast. You need to stop it before things get worse.

This guide will show you the common leak spots. You will learn how to find them, and what to do next.

You found water under the spare tire, so you need to act fast. First, pull out the spare tire and all tools. Get a shop vac or old towels and remove every drop of standing water. Then, clear out any mats or carpet in the trunk. This lets you see the bare metal and find where the water is coming from. Ignoring it will only cause bigger problems.

Why Water Gets Into Your Trunk

Water in the trunk usually means a seal is bad. It could also be a cracked seam or a clogged drain. Finding the exact spot can take some digging.

Tail Light Seals Are Common

This is a very common place for water to get in. Over time, the seals around your tail light assemblies can dry out and crack. Rainwater runs down the body, gets behind the light, and flows straight into your trunk.

Trunk Lid Seal

The big rubber seal that goes all the way around your trunk opening is called the trunk lid seal or weather stripping. This seal can get old, crack, or even get pinched. A bad seal here means water comes right in when it rains or you wash the car.

Sunroof Drain Tubes

If your car has a sunroof, it has drain tubes. These tubes run down the car pillars, often ending behind the rear bumper or inside the wheel wells. They can get clogged with dirt or come loose. When they clog, water backs up and often leaks into the trunk.

Rear Window Seal

The seal around the back window can also fail. This is less common than other leaks. But if the adhesive or rubber seal dries out, water can slowly seep in. It often shows up first near the top of the trunk opening.

Rusted Body Seams

Over years, the metal seams in your car’s body can rust. Tiny holes can form. Water finds its way through these tiny holes, especially after heavy rain. This is harder to spot because the rust might be hidden.

Ventilation Vents

Your trunk has vents to let air out. These are often hidden behind the bumper or in the side panels. They have flaps or seals that can fail. If they get stuck open or the seal breaks, water can get sucked in when you drive.

Getting to the source of the leak is the biggest challenge. Take your time looking closely at each area. A small leak can cause big damage if you let it go.

• Check all rubber seals for cracks.
• Look for rust spots on the metal.
• See if carpets feel damp in specific areas.
• Pour a small amount of water on suspects.
• Inspect the tail light assembly.
• Feel for wetness near the rear window.

How to Find a Trunk Leak

Finding the exact spot where water gets into your trunk takes patience. Do not just guess and replace parts. You need to actually see the water come in.

Remove Everything From Trunk

Start by clearing out the trunk. Take out the spare tire, jack, tools, and any mats or carpet. You want to see the bare metal of the trunk floor and sides. This makes it easier to spot water trails.

It also helps you clean any existing mold or rust. Get rid of everything that holds moisture. Use a shop vac or old towels to dry out the spare tire well.

Leave the trunk empty for your inspection. This way, any new water will be easy to see.

• Take out the spare tire.
• Remove all tools and the jack.
• Pull out any carpet or liners.
• Dry the entire area completely.

Clean All Visible Surfaces

Once empty, clean the trunk area well. Wipe down all metal surfaces and seals. Use a simple cleaner to remove dirt, dust, and grime. This helps you spot fresh water much easier.

Dirty areas can hide a small drip. You want a clean slate to look for water trails. Pay extra attention to corners and seams.

A clean surface shows water marks clearly. It also helps you see if any seam sealer is cracked.

• Wipe down metal floors and sides.
• Clean the rubber trunk lid seal.
• Use a flashlight to check tight spots.
• Look for old water stains or dirt lines.

Perform a Water Hose Test

This is the best way to find a leak. Have someone sit inside the trunk with a flashlight. You, outside, will spray water on the car. Start with low pressure.

Spray small sections at a time. Go around the trunk lid, then the tail lights, then the rear window. Wait a few minutes after each section. Your helper will watch for water coming in.

When your helper sees a drip, you found your leak! Make sure you isolate the exact spot. This water hose test is usually very effective.

• Have someone in the trunk with a light.
• Spray water in small sections.
• Start with the trunk lid seam.
• Move to tail lights, then the rear window.
• Spray the entire rear of the car.

Inspect Trunk Lid Weather Stripping

The large rubber seal around the trunk opening is often the culprit. Look for cracks, tears, or flattened spots. This weather stripping can get hard with age. A good seal should feel soft and springy.

Push down on the trunk lid from the outside. The seal should compress evenly. If it looks uneven or has gaps, it is probably letting water in.

Sometimes, a small piece of debris can get caught under it. This breaks the seal. Replace any damaged weather stripping right away.

• Check for visible cracks or tears.
• Feel for hard, brittle spots.
• Look for areas that do not compress.
• Make sure it is seated correctly.

Check Tail Light Seals

Unbolt the tail light assemblies. They are usually held on by a few nuts or screws. Pull them gently away from the car body. Look at the foam or rubber gaskets behind them. These are the tail light seals.

If these gaskets are compressed, torn, or missing, water will get past them. You might see rust or water trails on the metal behind the lights. Replace these gaskets if they are bad.

Sometimes, a loose tail light lets water in. Make sure they are bolted on tight. New gaskets are cheap and easy to put in.

• Remove the tail light assembly.
• Inspect the old gaskets or seals.
• Look for rust behind the lights.
• Clean the mounting surface.

Look at Sunroof Drain Exits

If your car has a sunroof, check its drain tubes. Pour a small amount of water into the sunroof drain channels. Watch to see if it drips out cleanly under the car. If it backs up or leaks inside, you have a clog or a loose tube.

The end of these tubes often gets clogged with dirt. Sometimes, the tube itself can disconnect from its fitting. This often causes water to go straight into the trunk.

Finding these tubes can be tricky. They often run down the rear pillars.

• Pour water into sunroof drains.
• Watch for water exiting under the car.
• Look for clogs at the tube ends.
• Check for disconnected tubes.

Check Body Seams and Drain Plugs

Look closely at all the metal seams inside your trunk. Use a bright flashlight. You might see tiny cracks in the rusted body seams. These are often covered by seam sealer from the factory. That sealer can fail over time.

Also, many trunks have rubber drain plugs on the floor. These are there to let water out if needed. Make sure they are still in place and properly sealed. A missing or loose plug is an easy entry point for water.

You can often find these leaks by looking for rust or dried water stains. These stains show where water has been flowing.

• Inspect all factory body seams.
• Look for cracks in old seam sealer.
• Check all rubber drain plugs.
• Search for rust spots on the trunk floor.

Once you find the leak, you need to fix it right away. Do not put off this repair. Water damage spreads quickly and costs more money down the road.

The Damage Water Causes in Your Trunk

Water in the trunk is not just annoying. It leads to serious problems. The longer it sits, the worse things get. You really need to fix it fast.

One of the first things you will notice is rust. Water sitting on metal eats away at it. This can damage the floor of your trunk. It can even make holes in the metal.

Next, you will get a bad smell. This is from mold and mildew growing in the damp carpets. That smell gets into the whole car. It is hard to get rid of once it starts.

Electrical parts are often under the trunk floor or in the side panels. Water can damage wires and modules back there. This can cause confusing electrical problems. Your lights might act weird or other things stop working.

Your spare tire can get damaged, too. The rim can rust badly. The rubber might even start to rot if it stays wet for a long time. You might need a new spare.

• Rust on the trunk floor
• Mold and mildew growth
• Foul, musty smell
• Electrical problems
• Damaged spare tire
• Compromised car value

How to Dry Out Your Trunk

After you fix the leak, drying the trunk is the next big job. You need to get every bit of moisture out. If you do not, you will still have mold and rust problems.

First, remove everything from the trunk. Take out the spare tire, tools, and all carpet. Get out any water with a shop vac or old towels. Make sure the bare metal is exposed.

Next, open the trunk lid completely. Let the car sit outside on a sunny, dry day. Good airflow helps a lot. You can also point a fan into the trunk to speed things up.

For stubborn moisture, use a dehumidifier. Put it in the trunk and close the lid most of the way. Run it for several hours, or even a full day. This pulls moisture out of the air and materials.

Sprinkle baking soda over the wet areas. It helps soak up moisture and bad smells. Leave it for a few hours, then vacuum it up. This will help freshen the area.

• Remove all items and carpet.
• Soak up standing water.
• Open the trunk fully.
• Use fans for airflow.
• Run a dehumidifier.
• Apply baking soda for smells.

Preventing Future Trunk Leaks

Once you fix a leak, you do not want it to happen again. Taking a few steps can help keep your trunk dry for good. A little maintenance goes a long way.

Regularly check your trunk lid seal. Look for cracks or areas that feel hard and brittle. You can put a thin layer of silicone grease on it. This keeps the rubber soft and helps it seal better.

Check your tail light seals once a year. When you change a bulb, take a look at the gaskets. If they look worn, replace them before they fail. It is an easy and cheap fix.

Keep your sunroof drains clear. Pour a little water in them now and then to make sure they drain freely. If they are slow, use compressed air to gently blow out any clogs. Do not use high pressure.

Avoid high-pressure car washes directed at your trunk or rear window. The strong spray can force water past seals that are barely holding up. Hand washing is safer for old seals.

Sometimes, the original seam sealer fails. If you had a leak from a body seam, reseal it with automotive-grade seam sealer. This adds a layer of protection to problem areas.

• Inspect trunk lid seal often.
• Lubricate rubber seals with grease.
• Check tail light gaskets yearly.
• Clear sunroof drains regularly.
• Avoid direct high-pressure spray.
• Reseal body seams as needed.

When to Get a Mechanic Involved

Sometimes, a trunk leak is more than you can handle alone. Knowing when to call in a professional saves time and prevents bigger headaches. Do not be afraid to ask for help.

If you cannot find the leak, a mechanic has tools and experience you do not. They can use smoke tests or special dyes to trace water paths. This finds hidden leaks fast.

If you have major rust damage, you need a body shop. Welding and panel replacement are not DIY jobs. They can fix the metal properly and seal it for good.

Any electrical problems from the water mean a mechanic should look at it. Water and wires do not mix. They can figure out what got damaged and replace faulty parts safely.

If you lack the right tools or simply do not have the time, a mechanic is a good option. Some leaks need panels removed or special sealants applied. This saves you frustration.

A mechanic can give you peace of mind. They can ensure the repair is done right. They will also confirm there are no other hidden problems.

• Cannot find the leak yourself.
• You see major rust damage.
• Electrical components are failing.
• Lack of tools or experience.
• The leak is coming from a complex area.
• You want a professional guarantee.

Final Thoughts

I hope this guide helps you find and fix that annoying water in your trunk. It is a common problem, but one you can usually tackle yourself. Getting it dry and sealed quickly will save you from bigger, more expensive repairs down the road.

Frequently Asked Questions

Is Water in My Trunk a Serious Problem?

Yes, water in your trunk is a serious problem. It causes rust on metal parts, which can weaken the car’s structure. It also leads to mold and mildew, creating a bad smell. Water can damage electronic components and wiring, causing electrical issues.

Can a Clogged Sunroof Drain Cause a Trunk Leak?

Yes, a clogged sunroof drain is a very common cause of trunk leaks. Sunroofs have drain tubes that run down the car’s pillars. If these tubes get blocked with dirt or debris, water cannot drain properly. It will back up and often spill into the trunk.

Are Trunk Lid Seals Easy to Replace?

Trunk lid seals, or weather stripping, are usually quite easy to replace. They typically pull right off and push a new one into place. No special tools are needed. Just make sure to get the correct seal for your specific car model.

Do All Cars Have Drain Plugs in the Trunk?

Most cars have one or more rubber drain plugs in the trunk floor. These are designed to allow water to escape if it gets in, or to drain during manufacturing. Make sure these plugs are securely in place and not missing or damaged.

Should I Use Silicone Sealer to Fix a Leak?

You can use automotive-grade silicone sealer for small cracks in body seams or around tail light gaskets. However, it is always best to replace a damaged rubber seal or gasket completely. Silicone is a good temporary fix or for very minor, hard-to-reach spots.

Will My Car Get Mold If Water Sits in the Trunk?

Yes, your car will almost certainly get mold and mildew if water sits in the trunk, especially in carpeted areas. Mold grows in damp, dark places. Once it starts, it is very hard to get rid of completely and causes a nasty, musty odor.

How Long Can Water Stay in My Trunk Before It Causes Damage?

Even a few days of standing water can start the rusting process and allow mold to begin growing. Electrical damage can happen much faster if wires or modules get soaked. You should remove all water and fix the leak as soon as you find it.

How Much Does It Cost to Fix a Trunk Leak?

The cost to fix a trunk leak varies a lot. If it is a simple rubber seal, you might pay $20-$100 for a new part and fix it yourself. If it needs a mechanic to find a hidden leak or a body shop for rust repair, it could be hundreds of dollars.