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PSA - Passenger side water leak

rampage

rampage

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For those of you who have replaced your heater core, make sure you seal around the tubes passing through the fire wall before you install the rubber hoses. There’s a lip on the outside of the firewall that funnels water directly onto the hoses and it travels down the tubes and inside the cab. My neighbor had his heater core replaced and they didn’t seal it so I had to work some rtv around the hoses the best I could. It wasn’t just a trickle, it was a steady stream when I ran water over the windshield. Even if you didn’t replace the heater core the old sealant could be dried up and cracked. You need to clean the old sealant with some soap and a toothbrush (hopefully one you don’t use :rotfl:) to reveal any cracks that the dirt is hiding.
 
Is there supposed to be a single foam seal in there that goes over both tubes?

I can see the part in my head, just can't recall how it fits in there and what it is actually sealing.
 
I think you’re right - that does ring a bell. It’s been eons since I’ve seen the factory sealant but now that you mention it, I do recall it being a foam. Whatever was sealing it though all got removed on this truck and not replaced. :doah:
 
rampage said:
I think you’re right - that does ring a bell. It’s been eons since I’ve seen the factory sealant but now that you mention it, I do recall it being a foam. Whatever was sealing it though all got removed on this truck and not replaced. :doah:
Click to expand...

I just reused whatever was in mine when I did my heater core, but if it's prone to leak, then maybe re-using a 40 year old foam seal isn't a particularly good idea!

I don't recall ever thinking to myself "I see what this is here for" so the fact it had taken a set and was not likely to make a good seal hadn't even crossed my mind. I just put it back where it had been before prior to replacing the heater core.

Cant get to lmctruck to check, not sure who else should have it. Here is what GM was using on some of the cars. Same general shape and idea, just not exactly the same. I feel like the truck one was probably either a single thickness or two different thicknesses but half and half, not with odd protrusions like this: https://www.npdlink.com/product/hea...inlet-and-outlet-pipes-to-the-firewall/205095

Only ones I've ever seen are original, so whatever the original shape was, I'd have no clue.
 
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