Cowl Plenum - Water Leaks to Interior
ModelsAll Omni, Horizon, Charger, Turismo, Rampage & Scamp
Subject
Water Leaks at Plenum & Cowl
Index
BODY
Date
February 11, 1985
No.
23-09-85
This bulletin outlines the recommended diagnosis and repair procedures which should be used to resolve plenum and cowl water leak complaints on subject model vehicles.
Proper repair requires pin point detection of where the water is entering the vehicle. To accomplish this, it will be necessary to water test the vehicle with a hose in the prescribed manner with an assistant inside the car to observe and locate the exact area of leakage. Often evidence of previous water tracking will also be helpful.
DIAGNOSIS
Remove front trim "kick" panel(s) from reported wet area and pull back interior carpeting from cowl and side cowl area.. Also pull back black mastic patch (if so equipped) from opening to expose cavity inside "A" pillar.
Apply water to the following areas separately to diagnose the path of the water entering the vehicle:
FIGURE 1 - Cowl Top Panel:
FIGURE 2 - Lower Cutout Inside Cowl:
A. Cowl Top Corner
Apply water to the end of the cowl top panel (Figure 1) by directing it underneath the end of the upper corner to check for an unsealed joint at the junction of the aperture/hinge pillar subassembly-to-plenum/side cowl subassembly at the base of the windshield. Water from this joint will follow down the hinge pillar cavity between panels #l, #2, or #3 and enter vehicle through lower cutout inside cowl (Figure 2).
FIGURE 1 - Cowl Top Panel:
B. Plenum
Lift hood and slowly hose test entire plenum and plenum end seam. Be careful not to splash water into air intake stovepipe (Figure 2). The two dominant sources of leakage here are (1) sealer skips in the end seam of the plenum-to-side cowl, especially in the area of the drain hole; this will appear from within along the flange of the plenum end, and (2) missing sealer
in the vertical seam of the aperture/pillar subassembly-to-side cowl, especially beneath the impact bar beam. Water draining from the plenum end drain hole dumps into the impact bar and is directed rearward into this seam. If unsealed, the water enters the vehicle also through the lower cutout in the side cowl.
Water draining from the plenum end into the impact bar beam also accumulates on welds beneath the impact bar and the antenna grommet. Any weld burn holes or nonseated or missing grommets will leak accordingly.
C. Dash Panel
Lift hood and hose test dash panel below plenum area thoroughly. Leakage can occur at attaching screws, grommets, and electrical bulkhead connector, etc., and enter directly. Leakage at dash panel-to-floor pan seam can also occur.
D. Wheelhouse
Turn front wheels for access and hose test the wheelhouse seam from inside the wheelhouse opening. Water leakage should show up from within the vehicle if skips in the sealer exist.
REPAIR PROCEDURE
From inside the vehicle during hose testing look for water leakage in the following areas:
A. Lower Opening in Side Cowl
Look into pillar cavity through lower opening cutout. Although this pillar cavity was designed to be a wet pillar with drain holes provided down in the sill area, water flowing down inside the cavity between panels #3 and #2 will hit the wiring and flanged edges splashing through the opening onto the floor area. Water appearing between panels #2 and #1 is permissible as it will not enter the interior.
FIGURE 3 - Cowl Top Corner:
1. If leakage is from water directed into cowl top corner at joint at base of windshield, repair by applying clear silicone RTV sealer with a nozzle into the cavity beneath the cowl top corner and dressing off neatly (Figure 3). Also direct sealer down 1" or 2" along seam which extends beneath fender. If better access is needed, remove last fender attaching bolt on top and loosen next 2 or 3 bolts to enable upper rear portion of fender to be moved outboard.
2. If leakage occurs when water is flowed into plenum, the vertical seam will have to be sealed beneath impact bar beam and just below beam. To obtain access to this area remove wheel and fender splash shield. Do not remove fender. With a minimum 3" long slim nozzle apply windshield or RTV sealer generously to this seam by placing the nozzle through the lower hole in the impact bar beam as shown. Assure that the entire seam beneath and below the beam is sealed. Also direct the sealer up the seam from below the beam as shown.
3. The windshield fence joint beneath moulding should be checked if leakage persists after above repair procedure.
B. Upper Side Cowl
When water is flowed into plenum, leakage may occur at plenum end flange-to-side cowl, antenna grommet, and impact bar weld burn holes.
1. Plenum End Flange - From inside of the plenum reseal the full length of the end seam with 3M Drip Chek, especially in the area of the drain hole.
2. Weld Burn Holes - Repair impact bar weld burn holes beneath plenum end by applying silicone RTV sealer from within the vehicle.
3. Antenna Grommet Hole - Water flowing out of plenum end drain is directed onto this grommet hole. If the antenna grommet is not seated properly it will leak - reseat accordingly. If hole is not being used or an aftermarket antenna without a grommet is used, the area will have to be sealed by some means, e.g. mastic patch cobbled grommet or silicone sealer.
C. Dash Panel
When water is directed to dash panel beneath plenum, leakage can occur at several places which can be repaired accordingly.
1. Attaching Screws - Leakage at sheetmetal screws can be repaired by removing screw, applying RTV sealer to hole and reinstall screw, and/or applying RTV sealer generously over the installed torqued screw head.
2. Grommets/Plugs - Seat grommets/plugs properly and/or apply sealer about periphery of grommet where it contacts dash panel.
3. Electrical Bulkhead Connector - Assure attaching screw is tight to seat peripheral gasket. Apply sealer about its periphery if needed.
4. Dash Panel-to-Floor Pan Seam - Repair sealer skips with silicone sealer accordingly.
D. Wheelhouse Seam
Water directed at wheelhouse seam from inside will enter vehicle immediately along this seam.
Missing or skips in the seam sealer can be repaired by applying silicone sealer locally.
E. AC/Heater Inside Ducts
If customer reports water coming out AC/heater ducts, water may be dripping into top of plenum air inlet stove pipe beneath its plastic cover. Water overflowing cowl top trough migrates between the metal flange and the plastic flange of the cover.
Remove stove pipe cover and wrap the cowl top trough upstanding flange with butyl tape in the area of the stove pipe cover. Reinstall cover. This seals between the trough flange and the cover to prevent the water overflowing the trough from getting to the top of the stove pipe.
POLICY: Information only