Water in the trunk of an R107 is common and important to fix, because it causes rust in the spare wheel well and trunk floor. The usual sources are the trunk seal, the taillight gaskets and the area around the trunk lid.
Where water enters
- Trunk seal: the rubber seal around the trunk opening hardens and shrinks.
- Taillight gaskets: the gaskets between the taillights and the body leak.
- Trunk lock and emblem area: small gaps can let water in.
- Rear window area on cars with the top up: water can run toward the trunk.
- Body seams: older sealer cracks.
How to find the leak
- Remove the trunk mats and dry the trunk.
- Have a helper run water over the trunk lid and the taillights while you look inside with a flashlight.
- Look for drips at the taillights and around the seal.
- Placing paper towels in suspected areas helps locate the leak.
Trunk seal
Replace a hard or cracked seal. Clean the channel thoroughly and check it for rust before fitting the new seal. Some seals push onto a lip; others need adhesive in places.
Taillight gaskets
Remove the taillights and check the gaskets. Replace them if they are hard or cracked. Check the area under the gasket for rust. When refitting, tighten the nuts evenly; overtightening can crack the lens.
Trunk lock and central locking
The trunk lock can be operated by key, and on cars with central locking, by the vacuum system. If the trunk does not lock or unlock with central locking, check the vacuum element at the trunk lock and the vacuum line. See central locking. A mechanical lock that sticks needs cleaning and lubrication.
Spare well rust
The spare wheel well is a low point where water collects. Remove the spare and inspect the well for rust. Check the drain plugs and make sure they are fitted. Small surface rust can be treated; perforation needs repair. See rust check.
Quick answers
- Why is my trunk wet after rain? Usually the seal or taillight gaskets.
- Can a bad trunk seal cause rust? Yes, especially in the spare well.
- Is the trunk lock vacuum operated? On cars with central locking, yes.
- What should be in the trunk? The spare, the jack and the factory tool kit, if it is still with the car.
- Can I seal leaks with silicone? Use proper gaskets and seals; silicone is only a temporary fix in a few spots.
