1977 rear bumper washer sealant?

[j79z28]

What are you guys using to seal the 4 washers that push onto the rear body section inside the trunk that help hold the rear bumper on? I am using the old school rope windshield sealant and am still getting water in my trunk. Any tips or ideas? Thanks

[roadking77]

I didnt use anything on my car, but I would think a seam sealer from a caulking gun may be more effective than the rope caulk. Not original but some coloured sealant of any type would do. Black silicone?

[Wallington]

The originals were a bright orange sealing rubber that appeared to be part of the domed washer surround and centre, compressing upon install. There were separate parts numbers for the top sealing washers and the lower standard domed washers without the seal. There was also a different sealing washer added between the bumper brackets and the trunk sheetmetal on the outside, according to parts diagrams. I haven't seen the remains but was likely the same rubbery foam type washers that sealed similar holes from between spoilers and trunk lid, likely crumbled and disintegrated upon removal.

Adding some sort of sealant is always a good extra, around the outer edge but also the inner edge of studs. Some snug fitting neoprene rubber washers that compress, fit tight on studs and slightly larger than the washers, are also a good method, and can be added to both sides of sheetmetal.

Here's a used set on ebay of the originals just for reference. I'm not sure of any similar items available new for resto use.

https://www.ebay.com.au/itm/124933302545?hash=item1d169ae911:g:QOUAAOSwoLphWwxS

[Wallington]

Actually, while looking for something similar stumbled across this from AMK Products and also sold through Classic Muscle (don't know who they are).
It's a 1.75" diameter rear bumper domed sealing washer for 78-81 Camaro models, and probably many others. 0.52" hole, for washer, not seal.

I haven't currently got a GM reference for the number #463120 and any useful Camaro bumper diagrams.

https://www.classicmuscle.com/p-1978-1981-bar-mounting-bolt-sealing-washer-463120

Edit: #463120 doesn't appear in Parts Manuals but is the inner trunk sealing washer in the 1980 Assembly Manual.

[roadking77]

I am pretty sure I used something like those washers on my 77. I think there is an orange such washer for the 79, but its been awhile since I have been to that part of the car.