MB OEM Roof Rail Install... with Problem

L

lukedog

Why Dogs Fly
It's supposed to be dry for a few days so I finally decided to put those first holes in my perfectly good van.

Taking out the plugs was not to bad. I broke off from the inside then drilled a hole from the top then the fun began removing.



Now i am having a problem. The white automotive sealer / adhesive shown is built up too high in the rail grove to allow the rail to sit flat..





Not sure what to do.

Should I try to grind it down a little?

I was not going to use any kind of caulking around the bolts but now I am pretty sure I will.
 
I

Inertiaman

Well-known member
Lukedog,

I encountered the same thing. What I found particularly irritating is that MB didn't design them such that the plastic "bridge" piece (that connect front/rear sections of the rail) to line up directly over that roof seam. Then the plastic piece could have been shaped to fit.

So before I finished my installation, I went to a local dealer and inspected several vans w/ factory rails installed. All of them crossed that seam without sealant. So I finished my installation without sealant and just ignored the slight curve of the rail over that seam. I've never had any leaks once my rails were torqued down, and the rain in Seattle has been HEAVY so its been tested sufficiently.

One thing to make you feel better: its really the round rubber washers at each stud/hole that are sealing the holes and preventing any water ingress. The thin rubber inserts at the rail edges are probably intended more for "seating" than "sealing" the rail to the roof. Even if those could successfully seal the length of the rail, there could still be water ingress at the plastic connectors in the front/rear/middle. In other words, I think that moisture will inevitably make its way between the rail and the roof; you just want to make sure it doesn't make it *inside* the roof.

FWIW, none of the factory installations I've looked at showed any evidence that sealant was used. I could see the very edge of that thin rubber bit at the bottom of the rail on both sides of each rail.

I know its frustrating when things don't seem "perfect" but in this case I can confidently say you'l be fine if you just ignore the "defect" and torque everything down, no sealant.
 
L

lukedog

Why Dogs Fly
Inertiaman said:
Lukedog,

I encountered the same thing. What I found particularly irritating is that MB didn't design them such that the plastic "bridge" piece (that connect front/rear sections of the rail) to line up directly over that roof seam. Then the plastic piece could have been shaped to fit.

So before I finished my installation, I went to a local dealer and inspected several vans w/ factory rails installed. All of them crossed that seam without sealant. So I finished my installation without sealant and just ignored the slight curve of the rail over that seam. I've never had any leaks once my rails were torqued down, and the rain in Seattle has been HEAVY so its been tested sufficiently.

One thing to make you feel better: its really the round rubber washers at each stud/hole that are sealing the holes and preventing any water ingress. The thin rubber inserts at the rail edges are probably intended more for "seating" than "sealing" the rail to the roof. Even if those could successfully seal the length of the rail, there could still be water ingress at the plastic connectors in the front/rear/middle. In other words, I think that moisture will inevitably make its way between the rail and the roof; you just want to make sure it doesn't make it *inside* the roof.

FWIW, none of the factory installations I've looked at showed any evidence that sealant was used. I could see the very edge of that thin rubber bit at the bottom of the rail on both sides of each rail.

I know its frustrating when things don't seem "perfect" but in this case I can confidently say you'l be fine if you just ignore the "defect" and torque everything down, no sealant.
Click to expand...
Concerned that the built in round washer will not seat all the way. Don't have a torque spec. Snapping off the screw isn't acceptable. Maybe I should remove some of the rubber along the rail allowing the round washer to seat better.
 
I

Inertiaman

Well-known member
The round washers will definitely seat. The stud/hole nearest that seam is still sufficiently distant from the seam to permit the aluminum rail to bend slightly and conform. I totally share your perspective that this seems a bit hodgepodge for MB OEM design, but apparently 1000's of vans are rolling the roads with the rails installed this way. I considered removing 3/4" of the edge rubber and shaping of the underside of the aluminum rail at the seam location with a half-round file, and then placing a short bit of 1mm EDPM under it, but ultimately decided it must not be necessary after confirming the factory installs had a visible (albeit tiny) gap under the rails immediately adjacent to the seam. I doubt removing a bit of the edge rubber, as you've considered, is going to help very much; that rubber passing over the seam gets squished immeasurably thin under the stud/nut pressure.

On torque, I used a 1/4" drive ratchet and did all the nuts in three passes: 1) just to flush, 2) snug but not super tight, 3) torqued tight to significant firm resistance. I accidentally forgot step #3 on three or four of the nuts on my final pass, and got some seeping on two holes during a very heavy rain. I tightened those nuts down like I'd done all the others, and never had any hint of seeping/leaking again. I agree it would be nice to have a torque spec, and perhaps a dealer mechanic procedure document has one, but the studs are pretty robust and the resistance ramps up pretty obviously as the rubber washers compress. Get 'em nice and tight, but don't be ham-fisted about it, and you'll be fine.
 
L

lukedog

Why Dogs Fly
we are expecting a few days of rain in a couple days. I have only worked on one side so far. I will take each nut off and apply some caulk before tightening. Can't hurt used sparingly.
 
R

RonR

Recovering Sprinter Owner
I had the same issue. My concern was having water (that may freeze) and tree sap / other junk collect counter the rail and cause rusting issues. I bedded the entire rail into a heavy bead of caulk to fill in the gaps, removing the excess that pushed out when I secured the mounting bolts.
Don't know if it makes a difference but nothing collects under the rail, lots of junk in the rail.
No leaks in Seattle.
Ron
 
hein

hein

Van Guru
I'd say carefully grind them smooth and set the rails in sealant or back the entire thing with VHB tape. You don't want water pooling under the rail and freezing. Debris (worst is road sand) can lodge under things and then start wearing on surfaces from vibration.
 
L

lukedog

Why Dogs Fly
I filed down two strips at each seam where the rubber gasket goes over. Used both a dremel tool and a flat file. I tightened the 11 nuts a number of times. Seems that after tightening and setting they can be re-tightened with same perceived torque if that makes sense.

Rains come tonight so we will see.
 
I

Inertiaman

Well-known member
lukedog said:
Seems that after tightening and setting they can be re-tightened with same perceived torque if that makes sense.
Click to expand...
I had the same sense when I tightened them down. I think maybe the rubber washers have some initial resistance that eventually compresses a bit more when they've been under pressure for several minutes?
 
L

lukedog

Why Dogs Fly
I must have tightened them a little too much... I'm not a strong guy ??? When we went out today there was some creaking that was not there before. :( I backed them off maybe 1/4 turn. Rain has not started yet.
 
N

nordich2o

New member
Lukedog and Inertiaman--Do you have Vendor recommendations for purchasing an aftermarket roof rail system to install on my 2015 144" high roof?
 
I

Inertiaman

Well-known member
We're both using the MB OEM roof rails. You can purchase them through most any MB/Sprinter dealer, though the pricing can vary. Can also be purchased from online genuine MB parts stores.
 
J

j5th

New member
nordich2o said:
Lukedog and Inertiaman--Do you have Vendor recommendations for purchasing an aftermarket roof rail system to install on my 2015 144" high roof?
Click to expand...
I recommend ordering from Jason White at Carriage House MB. Highly recommend him! Picked them up last week for roughly $240 shipped along with a few other things.
 
S

Sdavis

2014 144 HT
Resurrecting this thread:

Installing OEM MB roof rails on 144 passenger van. I can see these (nuts?) on the interior ceiling which I am guessing must correspond to the plugs on the roof exterior. Do these nuts get punched out or drilled out from above/below? Outside or inside? What's my next step?
 

Attachments

H

HarryN

Well-known member
There is some additional information in this thread.

https://sprinter-source.com/forum/showthread.php?t=40489

It is literally just a plastic bung pushed through a pre punched hole in the roof, and then painted over. The goal is to break the bung and carefully peal off the top so that you don't take a bunch of paint with it.

One way is to use a pliers and break if off from underneath. Another is to use a tool, such as an awl, and lightly hammer it into the center of the bung from on top to crack it. Plastic tools, such as plastic paint scrapers, etc can be helpful.

The sheet metal around the hole is slightly reinforced, but still pretty thin, so don't use any heavy forces.

On some vans, there is a molded foam block covering the most forward hole from underneath, and depending on what has been done on the van previously, can be difficult / nearly impossible to remove.

On a 170 length van, it can be a long, tedious process to carefully prepare each hole. Consider to have some tapered rubber plugs around to fill the holes as you make them in case you don't finish in one shot. The holes are 8mm / nominal 5/16 inch.

Not normally mentioned, but I like to use some green frog tape to hang a full length / height heavy drop cloth along the length of the van when working on top.
 
V

VanLifeFreedom

Member
Hey guys. In order to get the rails to sit flat you can use a sharp knife, small putty knife and a hammer. Knife the edges of the raised sealant and then chisel the sealant off the roof with a hammer and putty knife. After, add a thin layer of roofing sealant to the seem. For the plastic plugs, use a sharp flathead screwdriver and a hammer. Lay the tip of the screw driver on its side in contact with the edge of the plastic plug. Proceed to chisel it from the side. Take extra care to ensure you dont put any pressure downward into your roof and you just hit the side of the plastic plug. This will chip the plug off and then you just make sure the lower plug is clear and youre in business. This is done from the top of the roof.

When installing the rails we add a very thin layer of roofing sealant/adhesive to the rubber rings and the threads of the studs. This fills the void and provides peace of mind for the seal.


BTW we do not let a conversion through the shop without ensuring it has roof rails.
 
Last edited:
You must log in or register to reply here.

Top Bottom