WATER LEAKS ONTO FRONT FLOOR IN 1965-69 AMERICANS/RAMBLER
ARTICLE TAKEN FROM RAMBLER READER VOL.23 NO.1 2002
In previous issues of the Rambler Reader we have presented various trouble shooting analyses of the cause for water leaks onto the front floor carpet of the 65 to 69 American (Rambler). we revisit this problem because of the frequent occurrence and puzzling nature of this source . Some of this will be familiar , some of it new .
Here are some of the source for the problem , the order in witch the trouble shooting should progress , and analysis of the treatment :
1. Problem: Water drips from the end of the cowl lacing fastener clips onto front floor carpet . ( The cowl lacing is mounted on the engine side of the fire at rear edge of the hood. (foot note) this runs the whole length of the fire wall at top sticks out about a 1/4 " held down by the cowl sheet metal .
Analysis: The cowl lacing fastening clips if not properly sealed will allow water to drip directly through the heater core into the bottom of the housing accumulate to a point where it will run out of the damper pivot and unto the floor .
Solution: Seal
the lacing clips and test for a leak. 
2. Problem: The windshield gasket may be leaking , allowing water to soak through the windshield rubber gasket between the heater core and the plenum chamber and unto the floor .
Analysis: Water is leaking past the windshield gasket at the heater core housing .
Solution: remove the heater core housing and check the windshield gasket for moisture. A windshield leak may soak and saturate the gasket between the heater core and the plenum chamber and run into housing or directly to the outside of the housing and unto the floor . If the gasket is saturated with water , seal the windshield gasket by applying sealer on the inside behind the rubber lip to outer edge of the pinch weld flange along the top sides . While the heater core housing is out seal the seams around the baffle in the plenum chamber by reaching in though the opening in the dash and toe board assembly . Test for leaks.
( foot note ) During the time when these cars were new , we repaired it differently .
1. remove wiper arms extrusions nuts and the extrusions .
2. open hood remove all the 5/16 nut headed screws from cowl cover .
3. remove the cowl don't bent this panel and watch not to scratch the hood or the cover .
4. when you remove the cowl there should be a rubber seal 1" wide the length of the cowl this is lacing seal mention in problem 1 .
5. the sheet metal above the heater needs to be cut away as wide as possible for the repair. You'll see where the water is running in the heater core the dam area needs to be at least one inch high to kept water from running into the core .
6. use a material called dum dum can be purchased at NAPA comes in long strings about 1/4 in wide strips for sealing water leaks.
7. repair as needed keep area clean .
8. the area that was cut out can be taped over with duck tape or braze back together .
This section of article was written by myself a appeared in the Rambler Reader several years ago .
3. Problem: The plenum, chamber baffle may be admitting water through voids in the sealer around edges of the baffle .
Analysis: Gaps in the sealer allow water to pass the baffle edges .
Solution: Clean off loose and dried sealer and fill all gaps with fresh sealer . Test for leaks .
4. Problem: there may be some spillover at the flange around the heater opening when car is parked at an extreme attitude .
Analysis: The plenum chamber drainage system is capable of diverting water at the rate of 10 gallons per minute without spillover at the flange , with the car parked level at the curb . However , under extremely unusual parking attitudes and with a heavy windswept rainfall , water may spill over the flange . The water will then run down through the heater core into the housing and out onto the floor .
Solution: Install a rubber gasket on the flange which will raise the effective height of the flange at least one inch . AMC had a kit for this purpose , part #3598667 , Group 20.120 . The deflector in the kit can be installed and sealed by reaching through the heater opening on the underside of the instrument panel.
Or , never park on a steep hills . And if not fixed here is what will
happen!!
Disclaimer: This site is not intended to instruct or teach anyone in proper or safe methods of working on or maintaining a car and the author takes no responsibility for the use of the information contained herein.
