OEM MB Roof Rail Install tips

brownvan

2017 4X4 HR 144"
A couple of tips to pass on to whoever is installing their OEM MB roof rails themselves.
I looked at a few online videos which were helpful but thought I would mention a few things...(2017 2500 HR 4x4 Cargo 140")

My Cargo van didn't have any headliner but it did have the two foam pieces above the driver/passengers seat. They take abit of wrangling to remove if you want to keep them intact - start with removing the B-pillar plastic trim (seatbelts first) and undoing 2 grab handle bolts and 1 sun visor screw for both sides. This will free up the headliner enough to grapple with the foam. Or hack it out if you don't want to reinstall it again.
Note that the passenger side foam is attached with a piece of VHB to the inside of the roof. The foam pieces are "hooked" into features on the interior cage. Removing the foam pieces is necessary to access the 2 hidden roof plugs....

Regarding removing plugs- I found a medium temp setting on my heat gun and held 1" from the plug for 20 seconds (working from inside the van, under each plug), then use medium phillips drive screwdriver to tilt/break off the body of the plastic plug. Reapply heat at 1" for another 20 seconds, then push up/out the plug with phillips screwdriver. If it doesn't free, give it another 15-20 seconds of heat from below. Easiest to remove glue while it is heated or when it is really cold. Acetone also works but harms the paint.
Clean area where rails will mount on the roof channels thoroughly.
Foam pillow on step ladder top-face/bearing-surface held with bungee cords to lean against the side of the van...

After cleaning all the holes and removed excess glue (with can be scraped off as well), I painted the areas from the inside/outside, sprayed paint into cup and applied with small brush.

Assemble the OEM roof rails and prep threads with Vibratite VC-3. Apply silicone sealant (I used Dow 737) around lower shaft of each stud to black rubber seal on each stud. Also applied silicone in areas of the plastic rail-connectors (3 plastic pieces per rail, 4 regions per rail) that did not have perimeter rubber sealant to keep water out from under the rail if possible.

Place rail on roof upside down then slide and rotate to mate with holes.

Apply silicone sealant on OEM flange-nuts on bearing side in small o-rings. Lightly thread all of them onto the studs. I did one rail at-a-time doing this method. Then come back and get them further tightened to minimize assembly slop but not fully secure.

Regarding roof seam - I found I was able to get the roof seam to deform if I heated it with the heat gun (1" @20 sec) from above and torqued the bolts from inside. Somewhere around 20 seconds at 3 angles, including heating the rail, then hurry in the van and tighten the flange-nuts inside on either side of the roof seam and the roof seam will deform/flatten. Repeat to stress relieve. I chose a reasonable torque at 30 in-lb for the flange nuts - didn't have any instructions fyi so this may be lower than OEM spec.
Removed excess silicone inside with q-tips and clean with alcohol.

anywho, onward...
 

TaoOfWoo

Member
Great write Up! I think I have seen on here that silicone is not used because of its tendency towards rusting metal. I think that is why Sikaflex or Dap Gutter and Flashing or any non-silicone caulking is used for roof fan installs and such.
 

TaoOfWoo

Member
I ordered some OEM MB roof rails for $315 from our local Freightliner dealer and they did not charge shipping since I was willing to wait for their next biweekly shipment. They came from California and were not packaged very well. Got a hole in the box but it didn’t damage the rails too bad.
 

96r50

Member
I did this today and followed your advice about the heat gun. It worked really well and made removing the adhesive a lot easier. I cleaned up the rest with rubbing alcohol and painted a couple layers of white primer on the holes. I didn't use any additional sealant on the holes. We'll see how that works out in a day or two when the rain comes!
 

rararames

New member
I did this today and followed your advice about the heat gun. It worked really well and made removing the adhesive a lot easier. I cleaned up the rest with rubbing alcohol and painted a couple layers of white primer on the holes. I didn't use any additional sealant on the holes. We'll see how that works out in a day or two when the rain comes!
How'd it do? Any issues with moisture when installing sans sealant?
 

96r50

Member
So far so good. I checked it multiple times during that rain storm and others (still don’t have wall or ceiling panels in) and haven’t seen any leaks.
 

rararames

New member
Awesome, thanks.

We just did the install and about an hour later got a pretty good rain, not a drop in the van. The only thing I did was to paint the holes and use thread locker. Hopefully it holds up.
 
I'm having trouble finding a diagram showing the OEM roof rails, rubber seals (if any?), washers, and bolts. Can someone point me in the right direction or post a link?

I need to temporarily remove the roof rail and reinstall it.

Thanks!
 

brownvan

2017 4X4 HR 144"
Each side is a 2-piece rail with a plastic connector that lines-up on the rear-roof-seam. The integrated rubber seal is bonded to the aluminum rails and the steel studs are pressed in to the rail. The nuts have an integrated fender washer. I think there were 7 studs per rail for the 144". Each rail-side assembly can only be removed/installed as one piece after the rails are lined-up on the plastic connector since the studs are pressed into the alum rail, the installation/removal is a little different than aftermarket rails.
 

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THE

2018, 144, HR, 4x4
Odd, my OEM rails, 2018 Cargo 144 HR, came in tubes and there are only nuts, no washers of any kind. No integrated washer either.

THe
 

TaoOfWoo

Member
Just installed OEM roof rails yesterday, along with a Thule hideaway awning with Thule rack mount. Used heat gun for about 20-30 sec on each plug. Started with trying to scrape top of plug off with car panel remover tools, which are hard plastic, then get barrel of plug out from the inside of the van. Since there were two of us, it turned out to work faster and more efficient to heat plug from outside van and have the person inside the van push plug out with the rubber side of a hammer handle, to avoid damage if they slipped. Then came back after they cooled and removed sealant cold. Much less mess! Then just a wipe with acetone. Used DAP roof and gutter sealant in a donut around each bolt. Did not deform the seal where the roof pieces come together inside the rail channel. Did not seem to be much of a hump at all, plus we used the DAP on each bolt. Just tightened bolts slightly past snug since no torque specs. To remove foam blocks, just loosened b-pillar and pulled headliner back while the other person wrestled the foam out. Did not damage foam too much, still able to trim it down to use as a template or filler. Still don’t know what that foam is for! Seems like they designed the headliner around it! Followed “cyclevan” user’s video from YouTube. I think that they are Sprinterworld.com. FWIW, our rails are just like OP brownvan’s.
 

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cre8er

New member
Are the OEM rails shorter than aftermarket? Looks like they fall short of the front by quite a bit. How far in are they front and back? Preferably for both 144" and 170" WB?
 
I'm not sure if any of the aftermarket roof rails would be longer than the OEM ones, as long as they use the same pre-punched holes in the roof as the OEM rails. In the pic you can see the top side of the studs (pic is looking front to back) and the first one is pretty close to the front edge of the rail. I'm guessing so that there is not too much leverage force that can be applied on the front edge. If the rail was a lot longer and stuck out front farther I would bet you would need to make your own roof penetration, but that is just a guess. There is really not a whole lot of room in front of that first bolt, maybe 6" ish or less.



FYI, I do not think that the OEM rails come with a standard set of fasteners any more. I have heard of some coming with washers but no nuts, some with nuts but no washers etc. My set came with neither, so a trip to a hardware store that stocks metric size stuff should be planned for.

Popping out the plugs is easy-peazy. Hit them from the underside with a heat gun (I used medium setting) for about 20 seconds, then just push up on them. I used a wooden handle and they just popped up. Then clean up the top side and you are good to go.

Cheers,
JR
 

rfvega

Member
For the complete kit (rails and bolt/washers) the part name is "C Rail for A2", part number 665-607-52-64.
 

221206a

Member
For the complete kit (rails and bolt/washers) the part name is "C Rail for A2", part number 665-607-52-64.
I was able to use that part number a few yrs ago for my build. Tried using today to help a buddy on his build. I cant find the whole kit anywhere. MB online part stores, ebay, etc. Gonna call the dealer tomorrow if anyone else is having the same issue
 

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