sway bar through inner wheelwell and water leaks - PeachParts Mercedes-Benz Forum

JHZR2 · #1 08-17-2007, 10:47 PM

Hello,

As you may remember, my 85 had some rust spots. I had them professionally repaired by an auto body shop familiar with cars like mine. Good to go, right???

Well, not quite... still have to get to the bottom of why water was getting into weird spots to begin with. After all, all drains are clear, water flows as it should, etc. However, how would you explain rust like this:

In the driver's footwell/wheelwell, going through, and water like this:

Well, the water on the floor was partiall because of a small leak at the hole where the inner fender plastic liner (that makes the drain that always gets clogged, etc) gets screwed in, and a slight seam opening in the pocket drain. Solved on the outside relatively well and robustly. I spent the money and have been taking the time to do it right and seal it and prevent rust. However, one problem remains... when water comed out of the hood pocket drain, and onto the lower 'ledge', where the lower drain hole is, water can not only go through the hole, but also off theother side, towards the sway bar bushing.

The problem is that regardless of where the water goes, some will get into the spot where the sway bar comes through the inner wheelwell metal (you can see the bushing through this hole, and the hole would be up and to the left of what I'm showing in the first picture... perhaps Ill try to snap a shot of it tomorrow...).

Well, the rust was repaired by putting new metal on the outside and in the footwell of the driver's side. The metal on the inside of the car was left with a few small holes in the welding. Well, when water flows into the little gap where the sway bar goes through, it runs down the inner underside of the car's belly/floorboard of the driver, and it leaks in through the couple of small holes in the welding. If I pull the floorboard drain plugs, the metal in there is clean and rust free. However, there must be a gap or second metal piece under the metal that makes the driver's footwell, and water must run between them - or else why would there be rust in that spot in the first picture, and why would water flow in through the hole by where the sway bar bushing is, and end up flowing under where the rust spot was????

Is the welding wrong that it isnt 100% closed all around? Maybe... however, the problem that caused the orignal rust must still exist - water getting into the hole where the swaybar comes through, and making its way under there. That had to be why there was rust to begin with - water was sitting where it shoudlnt. Now that there are a couple of openings, it will run in, letting me know that there is still a problem (and also letting me spray antirust spray out through them to whatever is underneath!).

So, the question to this long-winded post is, how is water ingress at the sway bar entry point in the inner wheelwell controlled? Im tempted to slather the hole in asphalt for roofs, but doubt that such a method is the best solution.

Id appreciate any insight you may be able to give.

Thanks!!

JMH

biobenz240d · #2 08-17-2007, 11:04 PM

All the water leaks I have seen on my mbs are from the windshield moulding (front and rear). The water makes its way under the floor mats and eventually rusts out the floor pan. I used a silicone adhesive ,applied between the glass and rubber moulding and it stopped the leaks in all 3 of my benzs.

charmalu · #3 08-18-2007, 12:02 AM

that first picture at the top right there is a plastic tube. it part of the
plastic splash guard that goes under the fender above the wheel. the
bottom of the drain is blocked off, I removed the plastic shield and cut
out the bottom so it would drain. it drains the hinge pocket and drain
in the corner.
also with the splash guard out, check between the fender and the wall,
you might be surprised to find rust starting in there and the end of the
rocker.
I ended up removing both fenders and refinishing and sealing that area.
seems to be an area MB neglected. I`ve seen this on a few other cars
in the wrecking yard.

Charlie

JHZR2 · #4 08-18-2007, 09:59 AM

for better or worse, it is not the windshield gasket - Ive tested the whole car with a hose, and gone over everything with a fine toothed comb...

As for the drain (the plastic piece), I have had the same idea as you - makeit easier for water to get out and not clog. I removed the plastic pieces on both sides alltogether for now, and plan to put a few small holes in the bottom of each one. Fortunately everything is very solid without issue in the spots you mentioned. I have checked everywhere for surface and sub-surface rust. It is non-existant at this point, fortunately, however the seepage at the one point where the sway bar goes through is still an issue.

Pics to come... thanks!

JMH

JHZR2 · #5 08-18-2007, 10:36 AM

So the rust shown on the outer side of the driver's floor/wheelwell is shown as a repair here (from the inside):

It is fully sealed and undercoated on the outside, but when water runs through this:

Water will come through the few weld holes on the inside - itll run right in.

The question is, what is the standard MB mitigation scheme for sealing off and removing water that flows into that hole by the sway bar???

Obviously this mitigation is not present, thus why I had rust there to begin with. Rust repair is only as good as getting to the root of the water ingress problem, so any insight into how to seal that sway bar area, and why it is causing me troubles in the first place, would be most appeciated.

Thanks!!!

JMH

Army-Ant · #6 08-19-2007, 06:51 PM

I've got a 240D (W115) with the very same problem. Ive got water coming in and not sure as to its entry point. I did locate one possible source(but not the only), with the help of other forum users. On the 240D, there are black rubber boots in the door hinge area that house the vacuum lines for the locks. Mine were dry rotted...I tried taping them up but it didnt work. So I plan to remove whats left of the boots and foam fill the area where the lines run into the vehicle...someplace behind my hood release. This will prevent the roof water run-off from entering the vehicle. I suspect there are other points of entry under the car...luckily I have no rust spots in my floor boards and all the carpet has been removed because of the water problem so its easy to see around. I think that my A/C is also contributing to some of the water coming in. I plan on undercoating the entire floorboard areas on the inside of the car...thinking this may prevent water from coming in from underneath.
Keep posting...Im very curious to see how you address your problem.

TimFreeh · #7 08-19-2007, 07:03 PM

Quote:

Originally Posted by JHZR2

So the rust shown on the outer side of the driver's floor/wheelwell is shown as a repair here (from the inside)....

Was that repair done by a professional body shop?

JHZR2 · #8 08-20-2007, 01:27 AM

yes, why?

Don't need any fancy smoothing or blending of metal layers on a floorboard that will be covered by carpet. Just wanted the stuff done that I couldnt do, so that thenId have control of the rest, to do as research indicates to be best.

Maybe Im right, maybe Im wrong. I can always do it again, despite it being economically inefficient. Then again, I didnt pay much for the job, and the metal sure is solid now...

Any comments on the patch?

thanks!

JMH

TimFreeh · #9 08-20-2007, 07:58 AM

Quote:

Originally Posted by JHZR2

Maybe Im right, maybe Im wrong. I can always do it again, despite it being economically inefficient. Then again, I didnt pay much for the job, and the metal sure is solid now...

Any comments on the patch?

Apparently I'm a much better welder than I thought....

The patch panel looks fine (I've found that its much easier to control metal warpage/shrinkage when you use a circular patch) but the quality of the welding is pretty bad IMHO. As you have found out there is no way in the world that patch will be water tight. To be fair its pretty difficult to produce patch panels that are totally water tight - as you noted seam sealer/undercoating is frequently used to seal weld seams - and in my experiences they work well for this purpose. I've had great results using 3M epoxy based seam sealers for this application.

It looks to me like the guy that did the welding on your car did not have an auto-darkening welding helmet - the weld beads are not precisely placed on the intended area of the seam. It's hard to say from the picture but some of the beads don't look like they have good penetration. While I agree that cosmetic issues are not a big concern when you are dealing with patch panels that are not covered by body filler it would have taken about 20 second to use a grinder to remove the high spots on the weld before they applied the primer. By using a grinder to remove the high spots and then going back and filling the low areas with additional weld beads you can make patch panels that are almost invisible.

I know you dearly love the W123 chassis but I think you are fighting an uphill battle with rust issues on these cars - at least ones that have spent their lives in the northeast. I spent quite a bit of time/effort in the mid 80's trying to save W115 powered Diesel vehicles from the horrific effects of rust. What I found was that I'd spend a lot of time restoring a floorpan or quarterpanel only to find rust popping out from another area of the car next year. Rust never sleeps and even if you are able to figure out where the water is getting into the body of your car (and I'm a bit skeptical that its coming through the swaybar mount) I'd bet you are going to have other areas of the car that are going to require continuing restoration on at least an every-other year basis - the problem is that there is always rust on these cars that you can't see because it is hidden by undercoating or in an inaccessible place.

If you really, really, really can't live life without a W123 chassis car I'd look for one that has spend its life on Arizona or California and then transfer your interior and drivetrain into that car - then I would only drive it in the summer in New Jersey....

I don't mean to be pessimistic, I know that its like to really love an old MB Diesel and want to keep it on the road forever, but I wanted to give you the benefits of my experiences.

Best of luck - Tim

JHZR2 · #10 08-20-2007, 10:39 AM

Tim,

thanks very much for your insight! I greatly appreciate it. The welding elsewhere on the car is very smooth and done as you described, maybe this part was forgotten?

I agree that it is an uphill battle and that the chances of success are low. I dont need my w123 as a daily driver, it will be a garage queen that I use for weekend trips and whatnot. I have the space and there is just something fun about these cars to me.

Someday I plan to buy one of those ttally like new w123 cars (maybe even a coupe), that sell for $10-20k, but have super low miles and are in great condition. Until then, I plod along doing the best I can... For now getting our house remodeled is the bigger $$$ cost.

Anyway, you don't think the leak is from the sway bar mount, however my wife and I have gone over everything, and that is the one spot which when it sees water on the outside, do we get water inside. We have sprayed everywhere in a very systematic, precise way, and that is what we are seeing... It is the strangest thing to me, but appears to be what it is. To that end, I have to guess that MB had some plan for the water that came in there. I guess my plan now is to re-install the plastic fender liner (so that the water draining in the wheel well goes out in a more controlled fashion, and not across to the sway bar mount), and to attempt to enlarge the lower drain hole, so that the water will go out more readily. I may even build up a hill next to the drain, so that there is less water that is seen coming over from the drain hole to the sway bar mount, when it is very wet. Can you reccomend doing anything else? Is putting roofng tar or spray undercoating in the hole where the sway bar comes through a decent idea, or am I just creating more issues?

Thanks again!!!!

JMH

TimFreeh · #11 08-20-2007, 09:20 PM

Quote:

Originally Posted by JHZR2

The welding elsewhere on the car is very smooth and done as you described, maybe this part was forgotten?

Sounds plausible, glad to hear the other areas look better.

Quote:

Originally Posted by JHZR2

Anyway, you don't think the leak is from the sway bar mount, however my wife and I have gone over everything, and that is the one spot which when it sees water on the outside, do we get water inside. We have sprayed everywhere in a very systematic, precise way, and that is what we are seeing... It is the strangest thing to me, but appears to be what it is. To that end, I have to guess that MB had some plan for the water that came in there. I guess my plan now is to re-install the plastic fender liner (so that the water draining in the wheel well goes out in a more controlled fashion, and not across to the sway bar mount), and to attempt to enlarge the lower drain hole, so that the water will go out more readily. I may even build up a hill next to the drain, so that there is less water that is seen coming over from the drain hole to the sway bar mount, when it is very wet. Can you reccomend doing anything else? Is putting roofng tar or spray undercoating in the hole where the sway bar comes through a decent idea, or am I just creating more issues?.....JMH

I'm afraid its been a long time since I've had the inner fender liner out of a W123 but I think your plan on reinstalling it and sealing it as best you can is a good start. The best way to stop water is to have multiple barriers between the water and what you want to keep dry - kind of like using a storm door or hurriance shutters on your house, two seals are always better than one. As I recall there was a rubber gasket that was used on the outside of the inner fender liner to help keep water out of the rocker panels. Is the gasket present on your car? Is it in good shape?

I'm afraid I'm not going to be much help in chasing your water leak problems - I have lots of experience in trying to find/fix water leaks but I've had very little success.

I'll offer you a quick story about my most recent experiences in fixing water leaks in my 1991 300D turbo. About 4 years ago I noticed that the drivers side floor mat was getting wet - but it only got wet when I had driven the car in the rain. At first the leak was pretty small but over time it got worse until I finally had to try to figure out where the leak was coming from. I literally spent hours with a garden hose (and later, a pressure washer) shooting water into the windshield mouldings, floorboards, sunroof, rocker panels from every conceivable angle desperately trying to find the leak. I could not get the car to leak a drop of water under any of my testing..... Fast forward about six months of soggy carpets and moldy smells in the interior....... The registration has to be renewed and I fail the DMV inspection due to a small windshield crack. I have the windshield replaced and guess what? The leak totally disappeared and the foot well on the drivers side has been as dry as a summer desert for the last two years.

While I don't doubt its possible that you could discover a leak using a controlled testing environment with a garden hose I don't think its a 100% certainty that testing with a hose will exclude a bad windshield seal - at least I know it didn't on my W124.

Have you ever had the windshield seal in your car replaced? They are a known weak spot in the W123 and if it hasn't been changed I would seriously consider renewing the windshield seal.

patbob · #12 08-21-2007, 06:01 PM

Quote:

Originally Posted by Army-Ant

I plan on undercoating the entire floorboard areas on the inside of the car...thinking this may prevent water from coming in from underneath.

If there's holes through the floorboard, this won't prevent water from entering for long, then it'll just be hiding the progress of the rust.

JHZR2 · #13 08-22-2007, 02:10 AM

but if after extensive testing, the water ingress is from the hole where the sway bar goes through, what can be done? Nobody seems tohave a handle of the sealing mechanism that MB set up there to prevent water ingress - perhaps there was none, and what water came through just drained via the rocker drains... Itsjustnow that there is a small hole in the weld that I see the water come that way.

Without more knowledge from someone who has cut into the floors of these cars more than I, I shall not know.

Given that the hole in the floorboard is there essentially on purpose, by the skill of the welder, let's call it, what is to not prevent rust, assuming the hole is sealed up? its not like it is a rust hole with active moving oxidation in it, this is a hole that is the remains of a cut to good metal and welding in ofa patch?

Do you have a better solution?

Thanks,

JMH