How to Find an Air Leak in Your Cars Windshield

Driving down the road and listening to the wind whistle and roar through your car is fine in a classic convertible with the top down. It's not so hot if it is a persistent air leak in your windshield. Finding the exact spot where the wind noise is coming from is often time consuming and difficult. Here are several of the best techniques to find that wind noise so it can be fixed.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Paper Towels
• Glass Cleaner
• Compressed Air Source
• Mechanics Stethoscope
• Ultrasonic Leak Detector
• Painters Tape

1. Push out on the glass.
   
   If it moves then it is loose and must be removed and re-installed. This is the worst possible result and the easiest to diagnose. In the related articles section we discuss how to deal with this. If the glass is in solid and there is no flex move on to step 2.

2. Spray glass cleaner over the outside of the windshield where you suspect the air leak is.
   
   Then, from the inside, blow compressed air outward. In many cases the air leak will show up right away as the cleaner bubbles away. If the air leak doesn't reveal itself then dry off the glass cleaner and go on to step 3.

3. Place tape over the edges and top of the windshield in six inch lengths.
   
   Drive the car at highway speed and listen for the wind noise. If the noise is gone, stop and remove one piece of tape and test drive again. Repeat until tape removal reveals the air leak. This is almost foolproof but it takes longer than steps one and two. IF you still haven't uncovered the source of the wind noise proceed to steps four and five.

4. Drive the car at highway speed while an assistant listens for air noise with a mechanics stethoscope.
   
   In order to know what you are listening for turn on the air conditioner and place the scope in front of it.
   
   Another way to 'scope your air leak is to roll up all your windows and turn on the radio. Run your 'scope on the outside edge of the glass. If the music volume goes noticeably, you've found your air leak.
   
   Step five is what I use in the shop. It is the most reliable and the most expensive option to do it yourself.

5. Use an ultrasonic leak detector.
   
   The transmitter is turned on then placed on the dashboard. Run the receiver on the outside edge of the glass. If the receiver sounds a steady tone, you've found your leak.

Tips & Warnings

• Air leaks and wind noise are often tough to track down. If none of the above steps work, inspect the weatherstripping around each door glass.
• If the door glasses all appear alright, check the firewall for holes that lead may lead into the car interior.

Resources

• Source for Mechanics Stethoscope
• Source for Ultrasonic Leak Detector
• How to Replace Automobile Windshield Glass
• How to Pick An Auto Glass Shop To Replace Your Windshield

[rrrbs29]

on 7/30/2009 Great article. I never thought of an air leak before.