Leaky Sunroof on 993
 

The headliner and sunroof motor are removed from the 993 and the sunroof is welded shut. Of course it is leaking and the seats get soaked.

What can I use to seal the roof from the outside? The only thing that I know of is the sealant used around the tub. What is a better solution? Should I remove the seal and fill the gap? I was going to use the clear plastic adhesive (clear bra stuff) over the sealant for additional protection/longavity.

'the sealant used around the tub' comes in acrylic, urethane and silicone versions... And of course there are also sealants utilizing the same materials that are not labeled for tub use.

I would go for a colored (UV-resistant) silicone sealant as first choice, and a urethane as second. Surface prep is key, especially for silicones.

At Home Depot around here they have a variety of Dow and Sika sealants to choose from. You can also go to a building supply distributor and ask them which Dow silicones that have that may work best for you.

I would think you also have to be concerned about vibration issues, not normally an issue with bathrooms. Whatever you use needs to be flexible, and compliant with vibration and chassis flex. FWIW, you may want to also consider RV roof sealing products, because they're designed for that type of environment. But as DD mentions, anything you use will be meaningless without proper prep.

Good idea on checking RV stores. Although I suspect it is a pricy version of the HD stuff.

Would DD and HP like to share how to properly prep? Also, am I right in thinking that I should pull the stock seal around the sunroof off?

Even a properly functioning sunroof is not meant to be water tight. The "seals" around the edge of the sunroof door only seal out so much...the rest goes into the channels around the edge and drain out through the 4 drain tubes (one at each corner). 99% of all sunroof leaks are due to clogged drains...the water that does get by the seals can't get out and eventually spills over to seats and everything else. Wouldn't it be easier to unclog the drains? Hope this could help and I'm not stating the obvious.

From my non-engineering perspective, it just needs to be squeaky clean. Any oils, dust, dirt, etc will eventually foul the bond. Clean out any loose debris, etc. as much as possible, particularly on surfaces where you plan to put the sealer. If exterior painted surface, may want to even use polishing compound or similar to get any waxes off. A roughed up surface would help, too. Or maybe even take off all the paint, and then paint over the finished, sealed work; but this is probably overkill for a stinkin' race car. Use alchohol or such to lastly clean the surfaces, just before you apply the sealer. Finishing the cleanup 2 weeks before you apply the sealer is not a good practice.

Good points indeed! I guess also depends on how the sunroof is welded shut.

Best to seal metal-to-metal if possible. Proper prep is to clean, then scrape off any gunk/ residue, and finally hit the surfaces with mineral spirits or something similar to really remove any residue, etc.

I was assuming if the roof was welded shut there is a good chance seals, etc. were damaged and likely the drain system is no longer adequate or the water can bypass it where seals are damaged.

Was it welded by the same guy who did your aluminum tire rack? :shock:

I can't believe you call me cheap! Didn't you see the post about having sealant designed to handle the vibration? What's it going to cost you, an extra $3.00? Sheesh!

You are correct, except that I do not have a properly functioning sunroof that has a plugged drain. It is a converted race car where the interior was stripped, the drain tubes were removed, and tabs were welded on the inside to keep it permanately shut.