MC-5 front roof vent

Jsrcaptain · January 01, 2021, 07:51:07 PM

I'm wondering how the rooftop vent thing on the front of my 72 MC5 works. There appears to be a bolted arm up on the ceiling for opening and closing it? I think I might have a leak up there too. I can't find anything in my pitiful manuals about it.

Dave5Cs · January 02, 2021, 12:49:55 PM

Roof top vent ? or Emergency escape hatch?

Jsrcaptain · January 02, 2021, 04:07:23 PM

Definitely not an escape hatch. It's right up front by the ID lights.

benherman1 · January 02, 2021, 06:02:10 PM

I ripped off the ceiling in my 5A. I'll get you some pictures of how it works tomorrow. The mechanism you are describing sounds like mine so hopefully nothing changed from the '64 model.

benherman1 · January 03, 2021, 09:01:48 AM

The vent gets its air through a spot in the roof with louvers. It kinda looks like a dent from the top. I assume this is something related to aerodynamics to help the air in. As far as drainage goes it seems to rely on the bus being pretty well leveled in order to drain back out the top. There may have been some variety of seal around the flapper but if so it is long gone now.The mechanism from the bolt to the flappers is out of adjustment on mine. I'm not sure how this would be found out or repaired without the ceiling down so lucky me I guess.

Are you parked facing up hill? That may be the simple fix if nothing is letting water in where it shouldn't.

Let me know if there are any more shots/angles that might help.

Jsrcaptain · January 03, 2021, 10:40:08 AM

Thanks for the pictures. I'm not sure if it's the source for the leak. Just one of the suspects.

benherman1 · January 03, 2021, 03:40:24 PM

Almost all of my leaks have ended up being caused by a botched removal of random crap bolted to the roof. I had no less than 4 antennas, holes from 2 more, A collection of holes in a circle, and a botched AC install. The only other leak was caused by some accident damage to the back of the bus.

I also found that wherever there was a leak the whole section of fiberglass was soaked along with adjacent sections most of the time. You may want to bite the bullet and drop the ceiling panel for some insulation upgrades. If you are putting the OEM panel back up it ought to be straightforward enough. Just lots and lots of rivets.

lostagain · January 03, 2021, 04:53:01 PM

Heck, I've driven brand new buses (MCI J4500, Prevost H3-45) that leak like a sieve from around the windshield. I remember new MC5s in the 70s that leaked. It is a bus thing, lol.