Fixing Leaky Cab Lights on Heavy Equipment

[MikePhua]

Problem Description
An equipment owner asked for help dealing with cab lights that were leaking water into the cab. The leaks were causing moisture problems inside the machine, and they wanted to know the best way to seal the lights properly.
Common Causes
Several operators pointed out that leaky cab lights are a common problem on older equipment. Over time, the factory seals around the lights can dry out, crack, or shift, allowing rainwater to seep in. Some lights have foam gaskets that lose their seal, while others rely on silicone or rubber seals that break down with UV exposure.
Recommended Solutions
The most common solution suggested was to remove each light, clean the mounting surface thoroughly, and reseal it. Many recommended using a high-quality automotive-grade silicone or polyurethane sealant around the light housing. Some preferred butyl rubber tape because it remains flexible and can be shaped to fill gaps.
One user shared that applying sealant both under the light flange and around the outer edge gives the best long-term result. It’s important to tighten the light evenly when reinstalling so the seal is compressed properly.
Extra Tips
A few people suggested checking for hidden rust or corrosion around the mounting holes. If water has been leaking for a while, it may have caused rust spots that need to be cleaned and primed before resealing.
Others mentioned it’s good practice to check the cab roof for hairline cracks or loose rivets, which can also be sources of leaks near the lights.
Final Advice
Fixing leaky cab lights is straightforward but requires careful prep work. Removing old gaskets, cleaning the surfaces, and using the right sealant can keep water out and protect the cab interior. Regular inspection of seals and lights will help prevent leaks from returning in the future.