First and foremost on this day let me congratulate all the fathers out there for staying sane through all of this…..see, I can say that…..like Red Green would say “I’m there with ya”!
I have 2 boys that both have already done so much better than me, made me proud and will and already absolutely have made a difference in this world and brother ain’t that all you want?
Today they are out there doing their thing and I’m very happy for that….I’m in here plunking on this thing and doing something I enjoy doing and isn’t THAT all you can expect out of life?
Happy Fathers Day guys
So what does all that mess have to do with sealing your rails? ……..Nothing, it’s today and well…..I’m happy to be alive so lets get to it:
This subject is very close to me….you see all of us go through our lives dealing with stresses, I would just float in a gator floaty all day in the pool! Experiences are why we’re here but experiences from stress are things we all want to run from! We all know we can’t and when something just doesn’t seem right it brings on stress for everybody.
One such stress generator in my life are water leaks in the GMC motohome body. It is the bane of the existence of a motorhome wearing and airplane fuselage!
The body of the GMC is a composite of SMC (sheet mold compound) plastic and hi tensile strength corrosion coated 6061 aluminum. Not thin stuff like all trailers and motorhome of the day…Oh no, this is aircraft grade aluminum! Both materials…with different tensile strengths, flex rates and expansion GLUED or bonded not welded or riveted (in the design) to the roll cage aluminum frame. Glued mind you not screwed, welded, rivets but bonded together like ain aircraft! Why? When you build an airplane it must flex, it must expand and contract with altitude and it must withstand all kinds of stresses any good aircraft could encounter. That sounds awesome right?
If you were to build a motorhome like the tolerances the aircraft manufacturers do and would be needing servicing as an aircraft must have as per FAA regulations…..none of us could afford to buy an motorhome such as that! Even if you could that “continuous preventive maintenance would not allow the body to leak water….or the motor to drip oil…….the tires get too old…….or wiring chaffs and starts a fire! None of us….I say that not for sure because there are some GMC enthusiasts that do….but most of us imperfect humans react rather than act. Sorry but if we had a preventive maintenance schedule that if not done your motorhome could not be on the road I dare say MOST of the stresses of using one of these things would just go away…along with most of our wallets!
So if this awesome GMC motorhome body was designed at least like and airplane……….why would we expect it to perform any different! The top rails that run front to back where the roof meets the sidewalls is a “SEALING SYSTEM” which must be serviced on some periodic timeSo lets see, that could have be every 10 years maybe……..that would have been somewhere around 1988….when my wifes car was new!
BTW, lemme break this …boring to some….and let me show you a bright spot in my Fathers Day this year……….I gave 1 1988 Volvo……30 years old….to Janie this weekend Both older but still lookin good…….that car was NEW then!
Sort of silly comparison but It made me happy this Fathers Day to find such a thing for my wife and all of us to enjoy.
Back to the rails……. that alimunim rail with the drip rail is NOT the sealing component of that seam…… As you can see, this coaches roof had been brushed with some of that elastomer roof sealant put on toaster box motorhomes (that’s the white stuff up there) Under that stuff and the rail you see what is supposed to stop water from coming in it’s the butyl tape that rail is protecting . Someone way before actually tried to resel these rails……that’s the white stuff here But as you can see it did not do what it was supposed to. Where the aluminum roof seam, the front cap plastic and sidewall aluminum meet, my razor knife fully extended as you can see is poking the plastic inside panel of the headliner inside the coach…it’s an open hole!
The front and rear cap ends have an open hole to the interior if the sealant doesn’t stop it!
Plus the buildup of goo in the body groove where the rail is supposed to slide into is so clogged up That there is no way the extruded rail would ever fit into hey, and look at the goopage buildup on it! No way could this have sealed..oh and the drilled and tapped machine holes in the hollow body beam leaked at ANY of those screws……water gets in. The self tapping hex head screws the previous owner have put the rails down with could not HELP but channes water through the pitched windings of the screw…..in other words…probably every screw leaked! So with the gobbed silocone you saw above…this sealing system was long past it’s maintenance cycle and screwed up to boot!
Now you say “Why the heck did GM do this!!!??? To be honest no automotive seal had ever been made this way and also to such a tight tolerance….Ahhh, that’s it…some aircraft fuselage engineer figured he would incorporate a sealing system in the GMC body…a better seal if it is maintained.
I don’t think any of us ever thought about preventive maintenance on our coach bodies for water leaks. Water does NOT leak through hi tensile strength aircraft aluminum……it leaks at the perimeters and the penetrations. The perimeters are the cross seams at the front and back of the coach which BTW is an overlap seam of dissimilar materials…….that must be periodically resealed by the nature of the seam…..but the top rails are a very long seam….one that if the body were to go into a twist would pop that seam….So the aircraft enginerr designed a seal that would move that much but the sealant was the butyl tape under the rail……if you try and seal the rail from the outside, the seam moves too much even for sealants today I think.
Because of it’s design it needs to be periodically serviced and resealed….the cross seams too!
So to really seal those “penetrations” You would need to remove it all Search the roof for those holes and address each Note the rails are back on and resealed…. Then the cross seams are sealed and this roof can now be repainted and all the penetrations were sealed…the perimeters were sealed too and of the 10 top clearance lights that created 30 holes in the front and rear caps don’t leak………..maybe this roof will not leak until the coach is driven on a rock road and shakes all the seams which may pop sealant!
I’m telling you guys…body leaks is and must be a constant vigilance and expect leaks if the resealing system maintenance schedule is not kept.
We fix our cars when they break….they actually “maintain” an aircraft! Good thing cause you can’t pull over in the sky!
Another…”if you don’t do it all the way it will not work” things like brakes
So guys….yes it’s not an easy job but it can be done by you or someone with reasonable skills…some descent cuss words….and the right sealants to do the job. I’ve done some videos over on YouTube about this and hope to do more soon. I’m meeting with an internet firm on Tuesday that may be able to help us on line. The Co-op thus far has “gotten by with a little help from our friends” and man do I totally thank all of those….John D., Spacely, Lucy, Greg W., crap I can’t remember them all…..so maybe we can break into mobetta soon…stay tuned………
Where did that come from!…..I’m off and it’s Fathers Day! I can do anything I want……….. another thing I’ve been wanting to find time for was to put this together Found it in the dumpster…I’m not sure but it might be one made in the USA! I’ll say this, I didn’t use any metric wrenches…….well, it seemed like a sloppy 15mm on the rear wheel nuts……
This is also for Janie and her beach house. I had first rebuilt my Mon’s Schwin “Hollywood” to keep at the beach When JD stayed there last he commented I needed 2 bikes at the beach. OK, now we have 2. Still no internet or cable but there are good cell signals hey….we’re getting there.
If any of you guys are interested in baking your brain at a beach in Florida our Ormond by the Sea place has openings this summer. $50 a night..3 night minimum of full laundry service….Janie needs a job! A 1 beer walk to the water! Hey, if you’re gonna sweat it might as well be in a nice place and that’s air conditioned!
Anyway, I really wanted to get this off of my chest…this water leak thing. I tell you everyone has to deal with this…there is no “it’s done” it has to be a constant vigilance and maintenance. You can’t wait until you see a leak…that’s too lat for all motorhomes today and really too late for us too. The rails on this coach were what I would call a “worse case scenario”. Not only was the seal system comprimized but the screws that were used in an attempt to do the right thing doomed the repair. Hey, I’ll give the previous owner full credit for being creative covering the stove vent hole Hey really, I like it….call the coach “Bassmaster”…..the guy tried but screwed up his rails. At least he tried…if you have rusted torx pan head screws front to back on your rail it has probably missed 4 periodic reseals…..Do you have any water leaks? Hmmmmm….what to do……..
It was my please..really giving you guys part of my Fathers Day….I’m not away from my family….at least this one and I’m spending the rest of the day with Janie….Dads, don’t go sit in the garage, get off your ass and show some father stuff…at least once a year!!!!! Alright then…. we’ll see ya leter
Jim, you didn’t divulge what you use to reseal the roof seams and clearance lights. I used Dicor self-leveling sealant as it’s what was available locally. No leaks. What do you recommend?
William P Hubert says
I do support you on Patreron.
I have a 78 Royale that is undergoing a paint job up in upstate new York. Based on your older postings about the rail and sealing it we have removed both of them and cleaned the extrusion under the rail. Lost a lot of the fasteners so intend to move the rails a bit to drill and tap for new 10-24 SS Torx head screws. Got Bond and Seal from Wurth.
What is the best method of using the Bond and Seal for rebedding the rail? Is it important to reoved the butyl tape that is on the underside of the rail. ? Do you run a bead in the middle of the extrusion where the screws will fasten in? How many tubes do you use per rail?
Do you recommend using the B+S on the cross seam where the front and rear caps meet the aluminum.
Replacing all clearance lights, took off the the TV antenna and made that hole disappear.
Had this baby since 1983 so trying to keep it up for the next 2 generations that are following. Your site is great.
Thanks for your help