GMC Motorhome: Water leaks

There’s been a thread lately about leaking bodies letting water in.  One of the presents we get for having such a unique, composite body is water leaks at seams and expansion joints.  Its doesn’t take much of an opening for water to find its way in.  The most greivest leak possibilities are to top side rails on either side of the coachthat rail with screws from front to back is a COVER rail for the actual sealant under it.  Bobbing this rail with silicone or whatever might stop water for a little but really needs to happen……probably @ 10 years (It is a seam that must periodically be replaced).  Under it is thisit will look like this from the outside and you really feel that fibbing that crack will do the trick…..but it probably will notaactually, that pic is of the rail back on, sealed and new machine thread stainless steel screws installed.  Under that rail we found broken roof panel rivets and great openings where water could not have helped but get inGit’s, there IS no short cut in addressing these rail leaks, they must both come off, old sealant ground out, holes must be tapped out and new flexible sealant (there are several that will do a good job (NOT 3M S-5200).  That sticks too hard and eventually when it has to be renewed which it will….U will never get it off.

Bottom line is the GMC has expansion and overlap seams that need to be reneqed at time.  Its tough getting tots machine steel screws tapped into extruded hi tensile strength aluminum……maybe in 10 years next time they may not be so hard…..good luck
……now on to the rest of the punch list.

Fuel tanks are going inand Drew brought over another assembled 455 for check out…..should be the first “Nutcases” test runMore to do…..thanks for dropping by, see ya tomorrow

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