Recaulking skylights on ‘92 GMC Vandura/Explorer conversion

[Lorelei072]

I wasn’t sure where to post my question, but I need to recaulk the skylights on my 1992 GMC Vandura 2500 “Rallywagon”/ Explorer conversion van. The roof is fiberglass and my skylights leak. I bought some high-grade all-weather silicone caulk & removed one of the inside plastic frames thinking the glass just pops out, but it seems cemented in. Do I have to remove the exterior seals? They seem pretty dried out & probably need replacing. How should I proceed?

Edited to add 2 interior pics

 

[highdesertranger]

first off never use silicone.

it's real hard to tell from one picture but on most of these window/skylights the glass stays in the frame. here's what you need to do,

remove the whole skylight frame and all.

clean all existing sealant thoroughly. if silicone was ever use it must be removed 100% no exceptions.

rebed with new Butyl tape. marine is the best. the Butyl tape that compass marine sells is awesome, far superior to RV butyl tape

reinstall the skylight and tighten it down. give it a couple of days and retorque the screws that hold it down.

now trim off the extra butyl tape that has oozed out.

you can leave it like that or for extra protection use a Dicor product to seal around the edge. for a flat roof use Dicor self leveling lap sealant. for the sides use the Dicor non-sag lap sealant. actually on the sides above the windows I have used a thin bead of 3M 5200.

the next time they leak, more than likely you not own it anymore.

highdesertranger

 

[B and C]

^^^ Great advice (as usual).

 

[Lorelei072]

Thanks. How do I remove the entire piece with the frame? Pry it from the outside or push it from the inside? Is there anything else I need to remove beforehand?

 

[B and C]

My windows all have screws on the inside frame to connect it to the outside frame. They are on the flat part all around the perimeter.

Taking a closer look, the rubber holding the window in the frame appears shot. This may be a job for a window shop.

 

[highdesertranger]

can you post a pic of the inside?

B and C might be right it appears the window seal itself is bad.

highdesertranger

 

[bullfrog]

This one appears to me to use no screws to hold the frame. It looks to me like it will require a new gasket. The one you have appears to have a chrome trim piece which usually has to be carefully removed without bending it first. Once you have sourced a gasket you can run a single edge razor blade along the glass and cut off the lip of rubber gasket that holds it in. Do both inside and outside lips if you have to and then cut around the outside rim of the glass as any pressure on the glass will break it. Clean both the glass and the hole lightly sanding and painting the hole if you have to to to get a smooth surface. I would highly recommend sourcing an all rubber gasket that doesn't use trim. If you can't find the one piece gasket you can probably buy it by the foot and super glue the to ends together. When you install it this joint should be at the center of the long straight run which is least likely to have standing water and as the rubber will shrink over time try not to make it too tight on the glass but still able to be fitted into the hole. Using a little Dawn dish detergent and water insert the glass in the gasket and using the thinnest smooth weed eater string you can find wrap it twice plus a little extra around the gasket in the groove that goes against the fiberglass. Get two pieces of wooden dowel rod about 6 inches long and drill a hole in the center a little larger than the weed eater string. Insert the weed eater string and tie a knot in it to prevent it pulling through. After putting on safety glasses lay the glass and gasket on the outside top, spray everything down with soapy water and working from the inside slowly pull the string pulling the inside lip of the gasket over the fiberglass. The dish detergent will actually dry like glue after a few days. After you have broken the glass and healed up from the really clean cut most any glass shop will be glad to have your business. Good luck!

 

[Lorelei072]

can you post a pic of the inside?

B and C might be right it appears the window seal itself is bad.

highdesertranger

I added inside pics

 

[highdesertranger]

wow this is a tough one. can't really see how these are mounted. you would need to pull the headliner back to see. it does look like someone has tried to seal them before. if they used silicone you're in trouble. at this point it might be better to replace them all together or delete them. or you could try to just Dicor the crap out of them. it will be ugly and is not something I like to recommend. highdesertranger

 

[bullfrog]

A lot of fiberglass toppers mold in a lip that a double sided grooved rubber gasket seals to the fiberglass on the outer edge and to the glass on the inside edge just like the old windshields. You will notice in the picture there is a seam (this usually indicates an all rubber gasket which is sold by the foot) with an insert in the rubber gasket that most likely has pulled apart as well as rips and irregular tears where someone has tried to force glue or sealant on the inside as well as silicone possibly between the glass and the rubber seal. Unless there are screws on the inside under the headliner that screw into the trim strip on the outside (which I doubt) this is an all rubber rubber gasket. Usually the metal trim outside is joined at the ends with a inch or so long connector somewhere, it is hard to see but yours appears to be missing. You may get lucky if it is still there and be able to slide the connector one way or the other to reveal the end of the trim so you can start to carefully remove it. Wear gloves as the edges are usually razor sharp. I may be totally wrong as I stopped working on these sort of things in the 1980"s but if you can't find any screws it almost has to be as I described above. If you still can't figure it out take it to a glass shop and ask, they usually don't charge for giving you an estimate and ask what is involved to replace the seal.

 

[Lorelei072]

Thanks. There is a plastic frame that screwed on the inside. I removed that before taking pictures.

Desert High Ranger, can you elaborate why silicone is a problem?

 

[B and C]

I'll take a stab. If you ever have to remove it because something started leaking again, you have to get all the old stuff off as the new will not adhere to old silicone so you will still have a leak between the new and the old if it isn't removed completely. There is a reason why the RV industry doesn't use it. RV's move and flex, houses not so much but I won't use it on my house either. Have you ever tried to remove silicone? It is a big, labor intensive job.

Edit to add: It is cheaper but not really made for a mobile application.

 

[bullfrog]

Were there several screws or just a few that held up the trim piece? Did they screw into an outside frame part of the window sandwiching the fiberglass top or just into the headliner?

 

[Lorelei072]

There were 3 upper and 3 lower screws that hold each interior plastic frame which are so aged and brittle they are cracking easily. I'd like to try fashioning replacements of wood using a cardboard stencil. The exterior gaskets are also quite decrepit and likely to tear up if disturbed. I'm going to see if Explorer can provide replacements. In the meantime I found a marine fiberglass shop that applied silicone to the outside and provided estimates for reconditioning 30-year-old fiberglass.