GM N Body and L Body Cowl Remove and Water Leak Repair

Use the information at your own risk. There is no claim to accuracy.


Water Leaks are common for the GM N-bodies and the L-bodies. For a great reference article, see:

That plastic piece under the windshield wiper arms is called a cowl. To remove it, do the following:

Tools: You will need a "battery terminal puller" to remove the wiper arm. Often, a small three-leg puller will not work. The horizontal part of the legs are often too thick and the arms are often to "bulky" to fit into the very tight areas required. Pep Boys and Autozone sell (used to sell?) a cheap "battery terminal puller" for a few dollars. Those are the best. They are very small and compact. The puller does not have to be very strong. However, when my puller "decided to play hide and seek" with me, the only one that I could find is the beefier battery terminal puller (had springs and the whole deal) for ~$10. That puller *barely* fit in the available area. But, it did fit. Of course, about a month later, my smaller puller came out of hiding :-) and I did see at least one part store selling that cheaper and smaller puller.

Examples of battery terminal pullers (opens up in a new window):
General low cost battery terminal puller.
Craftsman battery terminal puller.
KD Tools battery terminal puller.

    Remove the windshield wiper arms
  1. Turn the car on and put the wipers around the middle of their sweep.
  2. At the end of the arms is a push on plastic cap. Remove that cap.
  3. Look at bottom of the arm on the *side*. You will see a small *hole*. Get the correct size drill bit to go into that hole.
  4. Lift up the arm. Align the outside hole with the side hole. Put in the drill bit to keep the arm elevated.
  5. Remove the nut holding the arm down.
  6. Put the "battery terminal puller" on the end of the wiper arm. Gently pull the end of the arm off the stud. Note: Some cars/models may need the wiper arms fully down, in the middle, fully up, to get enough access with the battery puller.
  7. Repeat for the other side. Note: Some cars/models may need the wiper arms fully down, in the middle, fully up, to get enough access with the battery puller.

  8. Remove the Cowl
  9. Remove all of the screws holding the cowl in place.
  10. Carefully, get the ends of the cowl from under the moldings at the side of the wind shield.

  11. Clean under the Cowl Area
  12. Go the passenger side. Find the fresh air vent. Find the DRAIN hole. You may not be able to see it. But, water should flow right down. Use a vacuum and CLEAN that whole area. If you have a Shop Vac, then you can also blow that area clean.
  13. Clean ALL of the area that is under the cowl. Use Simple Green or whatever if there is caked up dirt and grime. It must be clean to prevent the drain holes from clogging.
  14. Look at the gasket and the metal under the fresh air vent assembly. They should look good. If not, remove the assembly. For *minor* rust or gasket problems, you can use Ultra Copper or Ultra Blue silicon sealer.
  15. Look at the gasket that is under the top of the cowl. Often it breaks apart. A good gasket will prevent some of the water from entering the cowl area. You can get a replacement gasket at Home Depot in the area where they sell the weather seals for doors and windows.

  16. Reassemble
  17. Reassemble in the reverse order. The bolts the hold the wipers on do NOT require a lot of force. Just make them "snug".

Also, lift the carpet where the leak is. Remove ALL of the under padding that you can. That will just add mold and mildew and keep moisture. Plus, it smells BAD! Once you fix the leak, go to Wal-Mart and get some *automotive* carpet for about $6. Cut to length and shape. Put one or two layers UNDER your carpet to bring the carpet back up to the correct level.

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