4108 Upper Window Leak

[richard5933]

We've got a small water leak from the upper (roof level) window. Water is seeping in somewhere and showing itself about 4" from the center.

The gasket seems to be in good shape, so I'm not sure where the water is entering. My suspicion is at the point the vertical rubber meets the lower horizontal rubber.

Any one have any experience with this? Suggestions?

I could add a little black silicone, but I really hate band-aid type repairs. Especially if I'm just guessing at the cause.

Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB

[chessie4905]

You mean the astro glass windows? I'd be surprised whether that weatherstrip is still available, let alone the glass. You could carefully inspect it and look for areas where shrinkage is obvious.  Careful application of Shoe Goo in those areas should fix it. This stuff really seals; amazing. Available at WalMart and Ace Hardware in black and clear. Use a small flat blade screwdriver to apply it for a neat job. Clean area with some solvent first. Common to have those windows leak,esp after a couple of years of age.

[richard5933]

Astro Glass? Didn't know they had a name. But that sounds right.

The bus spent the first few decades stored indoors, so the rubber gasket is still in pretty good condition. The glass is near perfect. I don't know if the vertical/center piece of the rubber gasket is a separate piece or molded as part of the outer rim, but it kind of looks like there is a seam between the vertical/center and the horizontal piece. My suspicion is that the joint between them has failed at the center bottom.

I think that the black silicone window sealant is pretty close to the shoe goo stuff. It's possible to lay a pretty skinny bead of it, so if I don't have a better suggestion by the next warm day that's what I'll do. I've got a little paint touch up to do first around the upper edge of the rubber gasket, so I'll need to have a day at least 50 degrees.

For now, we've got a tarp secured over the window to keep rain/snow from seeping in. The way things look, it might be a while till we have warm enough weather to attempt a repair.

Has anyone had one of these apart that could confirm the way the gasket goes together?

[Brassman]

As water flows downhill check the areas up above the leakage too. A small roof leak can evidence in the side wall.

[chessie4905]

My gasket assy for the astro glass is one piece, although I think when it was made they used separate pieces and used some type of heat seal or permanent cement or something.

[richard5933]

My gasket assy for the astro glass is one piece, although I think when it was made they used separate pieces and used some type of heat seal or permanent cement or something.

That would confirm my suspicion. It looks like the only possible infiltration point is where the center piece joins the lower horizontal. I'll report back once it's warm enough to attempt a repair. Maybe we'll get a few warm days before winter hits in full force.

[sledhead]

if you have to use caulking put masking tape on the window 1/8 " from the weatherstrip all around the window glass then another  strip of tape  on the skin of the coach  1 / 8 " from the weatherstrip . clean the area with laquer thinners first . put the caulking on the hole area and smooth it out with your finger , when it looks good remove all the tape right away and pull it off and do not let it touch any thing as it will get everywhere . let it dry for 24 hrs 

dave

[richard5933]

Tape... That's a good idea. Thanks for the suggestion.

Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB

[eagle19952]

osi Quad is good stuff, imo, it is the best stuff

http://www.ositough.com/en/colored-caulk.html

[Oonrahnjay]

osi Quad is good stuff, imo, it is the best stuff

http://www.ositough.com/en/colored-caulk.html 

    Thanks, Don.  Perfect time for me to have that info.  (Not that it matters to me - I need "refrigerator white" - but they sure have a big range of colors.)

[richard5933]

Finally had a few warm days here and was able to troubleshoot.

The gasket looked good other than the ends of the center/vertical locking bead being a bit out, but I don't believe that the locking bead channel opens to the inside (at least it's not supposed to.)

I didn't see any place in the gasket with any type of gap. No place that was even remotely out of place. Stumped I was.

Then I started brushing away what looked like dark bird droppings along the center of the lower portion of the roof. Only they weren't bird droppings. They were holes, each with a slightly raised burr where the thread of the now-removed screw raised a bit of metal.

It looks like this was a factory error at Custom Coach. The holes were perfectly aligned with the center trim piece that held up the vinyl headliner over the driver's area, and I'd guess that when they first installed it they drilled too deep and used too-long screws (There was actually a hole through one of the OEM rivets) Someone must have seen the mistake and re-mounted the trim, only they neglected to ever fill the holes. Since the bus has been stored indoors for most of its 43 years it seems that this was not a big enough problem to be noticed and/or repaired up till now.

The water was coming through these holes, following the vinyl headliner to the end just under the Astro window, and then leaking out. I would have put money on the problem being the window which was directly above it, and I would have lost the money.

For now I used a small dot of electrician's putty on each of the holes to close them in. It tested OK with a heavy soaking from the garden hose for now. I didn't want to contaminate the paint with silicone since a new paint job is on the to-do list. If the putty doesn't hold I'll do something more permanent, but I'm hoping it will hold until the paint job so that they can do the job properly and hide it under the paint.

[chessie4905]

Apparently the company had some knuckleheads working for them too.