2001 MB rear back driver side water leak

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2001 MB rear back driver side water leak

June 12, 2021, 01:27:44 pm

I've been unsuccessful to sort out a water leak in our 2001 Mid-Bath rear driver side window.   There has been some corrosion that was repaired.   However, the latest is on the inside with the lower window paneling being bit soft around edges and a few small bubbles on new paint. So it appears I still have a leak.

I don't think there is major damage yet but not being able to see inside who knows? I'm at a loss as to the next step because there is no obvious problem. Roof, end caps look good, and I have a nice 3M 5200 bead all around the window including bottom. 3M 5200 also all around seams on end caps.

One area that might be a problem is the aluminum panel seams?   I could not find any site information on the panel seams being a water leak issue?   However, when I push on the panel near the lower window there is some movement at the seam.   Most everywhere else I checked the panel seams are firm. It's just a slight movement in the seam captured in attached photo.

The next steps that I think make sense since all other seals look good:
1) Use 3M 5200 on the aluminum panel seam from the bathroom window to the rear back window, and on to the end cap.
2) Prefer not to but I'm thinking I need to pull window out and reseal gasket everything.   Also this will give me a view of what exactly is going on inside. (Probably have body shop do this)

I also just purchased FLIR ONE Gen 3 Infrared camera (on sale at Flir for $149).   With 20 year old RV it seems water leaks are always going to be my biggest issue going forward so I need better trouble shooting tools.

Is there anything I'm missing to fix this leak? I really do not want to take apart inside paneling and figure resealing the window I'm at least getting something done.   Once window is pulled, I'll know whether I need to start taking things apart on inside.

Re: 2001 MB rear back driver side water leak

Reply #1 – June 12, 2021, 01:47:16 pm

"I could not find any site information on the panel seams being a water leak issue?"

In the nearly 20 years that I've been a member of this forum I cannot remember anyone who had a leak at the aluminum panel seams! In so far as I know they are formed to be self sealing with 'J' shaped edges that overlap.

I have the feeling that you have already isolated the problem to that window.

Your photo was somewhat confusing due to the fact it was so close up. Try sending a broadside shot a bit farther away.

Re: 2001 MB rear back driver side water leak

Reply #2 – June 12, 2021, 04:53:04 pm

Hi (other) Larry; First I would suspect a roof leak at the edge (top rail) seam near the back that is traveling down to puddle at the bottom of that back rear window. Next I would suspect water getting in at the top seam of the window near the aft end that is traveling around the window to the bottom. You can remove the metal trim around the window. It is pretty well sealed to the side wall, so I don't think the window will fall out. You will be able to see the condition of the wood at the base of the window frame inside the wall. As Larry Wade has stated, a 2001 will need the top caulking around the window frame resealed by now. I think my '99 used that gray butyl rubber goo as the sealer around the windows, and it may have small cracks letting water in at the top of the frames by now. A friends 2001 MB had such a leak on the passenger side rear window. That probably depends on which window got the most sunlight. RonB

Re: 2001 MB rear back driver side water leak

Reply #3 – June 12, 2021, 06:06:33 pm

May not be an issue at all but when I resealed my windows I left the bottom edge of the window alone and only resealed on three sides so the water would have a place to drain out. Like Ron said, look the roof over.

Jon

Re: 2001 MB rear back driver side water leak

Reply #4 – June 14, 2021, 08:41:49 am

Ive pulled the aluminum panels off and I can confirm there is a significant overlap design to avoid water intrusion while allowing expansion/contraction.

Sealant is also applied where the panels connect, but even without sealant you would have to hit the seam with a pressure washer for a long period of time to get any water leaking in from what I have seen.

On my rear bath the drivers side rear panels near the rear corner are pretty loose at the joints but like I said, no water should the going in unless you are forcing it into the joint.

Re: 2001 MB rear back driver side water leak

Reply #5 – June 14, 2021, 12:17:58 pm

Quote from: JonS - June 12, 2021, 06:06:33 pm

May not be an issue at all but when I resealed my windows I left the bottom edge of the window alone and only resealed on three sides so the water would have a place to drain out. Like Ron said, look the roof over.

Correct, when resealing windows, always leave the bottom of the frame unsealed, to allow a pathway for water to escape if it penetrates the walls. It is a standard technique in the building trades, water needs a way out or it causes rot, of which your rig has some inside of any soft wall. By the time things get soft, the damage is done and continuing.
I have never found a horizontal wall seam that caused a leak, it's always on a seam of some sort.

Most rear leaks come from the end caps, they can look sealed but still allow water to leak in.
MBs also have leak issues around the back window, both around the frame and in the window itself where the rubber dividers sharing and allow leakage.
Have the roof seams been resealed or covered with Eternabond tape?

A few RV and body shops have the ability to pressurize the interior using a large fan that forces air in through one of the roof vents. When pressurized, the exterior can be 'painted' with soapy water, which forms bubbles are any leaks.
It's the only method I have found that actually shows leaks, my FLIR infrared camera has been worthless for finding leaks.

Larry

Re: 2001 MB rear back driver side water leak

Reply #6 – June 14, 2021, 05:27:54 pm

Thanks so much for taking time to respond everyone! See updated photos. looks OK except the Luggage Rail which is embarrassing.

The roof seams look good with both leveling compound and Eternabond Tape on all seams.   The exception is the Luggage Rails which look pretty rough and cracked but without obvious leaks. All windows within last two years have a bead of 3M 5200; however, I have made the error of also beading the bottom of windows. End caps seams are also sealed with 3M 5200 but it seems after a trip stress seems to loosen connections. Actions/ Questions:
1) Do I need to remove the bead of 5200 on lower part of all my windows?   I only have this one soft spot so it seems like the leak is a bigger issue. Maybe only remove after higher priorities are fixed?
2) I'll go ahead and reseal all the Roof Luggage Rails since they look rough and original. Maybe this is the highest probability cause?
   3) Agree damage is ongoing until resolved.   This seems to make the case to pull the window? Do you think removing window and casketing/ resealing properly with 5200 is my best plan?
   4) For the Rear Window window dividers are there new rubber strips that can be purchased from Factory? How does one repair? The look good but a bit baked.
   5) Should I just make sure a good seal with 5200?   Or should is now the time especially driver side leak to pull off my end caps?
   6) 5200 around rear running lights?

My gut feel is this order so I'm likely answering my own question: 1) Reseal all roof Luggage posts, 2) Reseal seams as needed end caps (outside only), 3) Pull Window to inspect damage to know if inside rebuild is needed, re gasket and reseal outside with 5200 (not bottom). 4) Rework rear window divider rubber (but not sure how?).   4) Sell a new FLIR camera on Ebay.

LarryD

Re: 2001 MB rear back driver side water leak

Reply #7 – June 15, 2021, 01:32:05 pm

If the luggage rack was leaking, you would have damage in the ceiling, near the leaking window..

For sealing the individual glass panes, in the rear window, this is the best product I have found so far.
Permatex® Flowable Silicone Windshield & Glass Sealer – Permatex

Larry

Re: 2001 MB rear back driver side water leak

Reply #8 – June 15, 2021, 06:33:57 pm

You may want to consider getting an “un-hesive” like Un-hesive 3M 5200 Sealant and Adhesive Remover to help dissolve the adhesive bond or cut the adhesive away. Be careful, if you pull on the 5200 it will take the paint with it, don’t ask me how I know. 😳

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