: Does your car leak under the dash? This could be the cause:

Highway Star
08-07-11, 12:10 AM
If you are having a strange leak from under the dash of your '70s' ('80s?) Caddy, be sure to check for cracks in the plastic-fiber heater box housing under the right-hand cowl vent. Over the years the housing will develope stress cracks near bolt/screw areas, which will result in an interior leak under the dash when it rains or car-washing. You will have to remove the cowl screen just below the wiper area. If you have a crack, it will need to be filled with a good epoxy, and sealed with something for good measure (I used rubberized undercoating over the epoxy). Here is a picture of the crack I had in my '79 CDV:


08-07-11, 12:38 PM
Thanks man. I'll have to check this on my 78 fleetwood it leaks under the dash on the drivers and passenger side.

08-08-11, 07:16 AM
Thanks for the info! Over the decades some of the various plastic parts do degrade from age and sun exposure.I bought my '78 Deville over a year ago from an older gentleman who had it stored in a country barn for half of it`s life,so most of the plastic parts are holding up well-----except for the dashboard which has a crack in it.
It seems impossible to find another dashboard the exact same color so i`m leaving it as it is for now.
I had a water leak 6 months ago,it took me a week to find it was coming from the moulding area on the top of the windshield.I ran a good bead of clear silicone along the entire top channel between the moulding and the vinyl roof---not a drop of water since.