ETA 1-9-2023 Subject vehicle: 1996 Sonoma SLS RWD 2.2L MT Reg cab, 70k miles. Over ~18 months, as I infrequently worked on this problem, this thread morphed into instructions and a collection of reference photos. Some of my comments and photos in this 1st post did not well support that, so I...
Do you have any suggestions for sealing the bulkhead “connector” below the Cowl Drain Outlet on the R side for circa 1996 vehicles? I will call it a “connector” for simplicity. It is a very high water flow area, unfortunately. If I understand correctly, this connector was relocated to the firewall in one of the subsequent years, if not the very next model year. Probably a wise engineering decision.
I will explain factory installation as I understand it. The 2 – halves of the connector are split by a vertical seam into a left and right side. They apparently snap together, and were filled with a clear rubbery compound where the wires pass through. The top and bottom of the connector seam around the screw holes do not appear well to be sealed by any compound. The connector attaches to the cab with 2 – sheet metal screws. An ~¼” thick seal is sandwiched between the cab and connector. I appears to be sponge (foam) neoprene or similar. There was an additional, small piece of thin, butyl tape/ribbon applied to the cab over the top sheet metal screw hole. The top of the connector bedded in that. The top sheet metal screw also holds the plastic water deflector in place. The deflector is in no way sealed to anything; is a bit flimsy; but is well contoured to the body of the connector. Water entering into the top of the deflector will make contact with the side of the connector & neoprene seal. I actually am not certain what purpose it serves. Not shown is a weighted, rubber flap that covers the Cowl Drain Outlet; maybe to discourage vermin from entering.
The ¼” seal is compressed a bit, but not in terrible condition. What would you suggest for sealing this pass-through to the cab interior? I can source some butyl sealant to replace the small ribbon/tape I previously removed; screw the connector (w/ original seal) and deflector back in place; and replicate the original, factory solution. However, I do not want to remove all the front end sheet metal again to correct water intrusion to the Cab interior.