Roof leak

[jjrbus]

 The amount of knowledge iI have aquired over the years from you guys is amazing. Thought I should share this one.
I have had a tiny almost unoticeable roof leak in the rear of the bus. for a long time I thougt it was condensation. But as time went on it became obvious, although tiny it was a leak. I drove in the rain for the first time in years and the leak let in enough water to make me decide it needed to be fixed.
I have a Saudi MCI5C with the sunroof so this may not be simple. In the rear where the ememergency exit was I had installed an AC unit and later relocated it, This is the area where the leak is. Lucky for me I had coverd the hole in the outer roof with a 4X4 panel of sheet aluminum. I removed the sheet and looked at the patch over the inner roof, many rivets, all the pull type but can see nothing that screams out leak.
I clean the roof and use a brush on roof coating to get all the pop and pull rivets. I had the bus spray foamed when converting and thought a leak would never be a problem!!!
Today it rains and ir rains hard!! The leak is worse? What the???  This is normal for a bus, you fix something and it is worse, I'm use to this.
I'm up on the roof scratching my head, I can see nothing, I have visons of pulling the entire outer roof and slopping up the whole thing.  I have the wife watch inside as I go over the area with a hose. Nothing! I expand the area, nothing???
Then I rememberd something that was on this board at one time.  I get out the air hose and show the wife where I want her to point it as I go on roof with soap and water.  I am up there 10 minutes with her blowing air into ceiling and nothing? I have removed inner ceiling, I can see where water is comeing through foam, she is directing air into that area?
Its gotta be there somewhere, I look and there is a "hat" channel that the outer roof ataches too.  I squirt some soap inside it and we have bubbles The reason the leak was worse was the coating had formed a dam and allowed water to pool inside it.
It is riveted to the outer roof and I do not want to remove and reinstall it. That may make more problems. I am contemplateing filling this with spray foam, if water cannot get in it cannot leak.  Any other thoughts or ideas??   Jim

[Hartley]

An off the wall Idea....Yup...More Insanity..

Get a spray can of undercoating, add one of those nozzle tubes ( like a straw. )
and spray it up into the hat channel, Might need to drill a hole to get the spray into the right place but thats fixable if you get the leak sealed up.

Just a whacko Idea... May or may not work but would be better than shooting foam in and finding that it didn't work later.

Dave...

[Barn Owl]

Can you post some photos? It might make it easier for us to help you with a solution to your problem.

[luvrbus]

  Jim you can always use Eternabond tape to seal it with

[jjrbus]

A picture! I have been here long enough to know everybody is not looking at what I am looking at!!! I am going to use Dr Daves idea. The hat channel runs the length of the bus and is about 1 1/4 X 1 1/4" X 4 ft long,With the "rim" fastened to the bus or I am looking at the closed part of the channel. It will need 1/4" holes drilled every 8 inches for either foam or undercoating. If the first coat does not work I can add a second. If that fails a small block of C4 will be the final option!!

[Barn Owl]

A picture! I have been here long enough to know everybody is not looking at what I am looking at!!!

I couldn't disagree more, and you know the cliche. Nevertheless, just trying to help, and you asked. But then it's your problem, not mine.

I would not use foam, I like the flexibility of undercoating better.

Good luck....

[JohnEd]

Foam and undercoating need exposed to air to outgas and harden.  If the chamber is big enuff the foam will never harden....at least according to the mfr. rep. 

I don't know if you can do this but I would suggest you investigate a "two part" self hardening, epoxy like, substance for filling.  Find a way to inject it with force so it tries to follow the leak path.  I would drill a input hole in one end of the channel and a exhaust hole in the other and when it got full I would screw in a stopper screw and finally pressurize the chamber one last time and stopper that hole also.  If the leak has corroded the channel and it dissolves you will still have structural integrity due to the resin.......the last part is a joke

HTH

John