Part number for bulkhead seal?

[shifty]

Almost got all my water leaks fixed except 2 in the cowl/firewall area.

Need to know if there's a OEM seal P/N for the bulkhead behind the coolant overflow - circled in red in the attached pic. Hit that thing with a hose this weekend and water poured into the floorboard. Can't find in GM's catalog.

Also ...

I'd love ideas where my last cowl/firewall leak may be. I read 50 threads around the internet leading me to patch these already (all were leaking):

• Cracked seam sealer on either side of the cowl, near hood hinges.
• Leaking cowl screw sitting above the airbox opening.
• Cowl hole over above the airbox opening (Tahoes same year have a plastic cover there).
• Checked the antenna grommet, it's prefectly good as you see...

If I run a little water inside the cowl, I leak behind the blower motor. It's almost like the seam sealer around the airbox opening itself is cracked? I can't see in there though.

[Palf70Step]

I don't remember them starting till the GMT 800, but does your's have the quick release heater hose connectors on the firewall? Mine leaked after the got a bit old, and it did it the way you are describing. I think they just used black RTV on that, least that is all I have ever seen on them.

[shifty]

I'll need to check when it's light out, Bill, you may be right. I will say though - the water coming into the cab definitely only comes in on the passenger side, it's clear as spring water, and doesn't smell like it has coolant. It also only comes in when raining. I park on the street, so the truck is naturally pitched with the passenger side lower than the driver, so when rain hits the truck, it naturally moves towards the passenger side.

I was shocked at how much water was leaking in from this seam right here on the passenger side - that bolt head is the hood hinge and the white is the coolant overflow bottle - look at those cracks! I used Flex Seal to re-seal this entire area on both sides and that reduced about 50% of the water I was seeing during rains on both sides. I wish I had the skill to completely gut all of the seam sealer on the cowl and re-seal/paint. It needs it.