Common spots for water to leak into the cabin in W115?
 

Hey folks,

When it rains I've been having water pooling in the passenger front footwell of my 1974 W115. I've got the mat out of it so it's no longer soaking it all up, and have resorted to manually mopping it out instead.

I've recently had a couple of rust holes on the footwell/bulkhead there welded up and also sealed/protected the entire floorpan (such a satisfying job I might add!) but I'd rather just have a dry interior than constant mopping after it rains!

I can't see anywhere obvious the leak is coming from. I was hoping folks here might have some more insight?

FYI, there's no electric windows or central locking on my car for added wires to allow water to drip down!

Thanks :)

Could the windshield seal be leaking with the water running down the inside of the firewall?

Mine used to do that. I fixed it by (1) replacing the windshield seal and (2) putting silicone caulking in the vacuum line harnesses between the body and the doors. For the latter, the original rubber snaking insulation around the vacuum lines is probably cracked away, so water between the doors gaps will run right in. For me, it was a lot easier and cheaper than replacing the rubber shielding. I did one of them first and it helped but didn't entirely fix it; water in either will end up inside the car.



-Henry

Thanks for the suggestions! I'll investigate both and go from there :)

I have run into both of these. And that windshield seal is a common place for leaks. These are not that expensive and are not even that hard to do. But you might want to just get a new windshield and seal installed at the same time by a glass shop.

Check the seals around your taillights. These are also prone to leaking water into the trunk. I have tried resealing them but nothing works as well as just replacing them. Again, not hard to do.

If the leak is from the windshield, you should also check the rear passenger foot wells. It's common for water to run under the carpet and accumulate back there.

https://i.imgur.com/8UJP6k1.jpg

Ok, so this is what I'm working with (pretty obvious now my attention has been drawn to the windshield seal!)

Just spoke to an autoglass place here and they're quoting me (ballpark figure) around $300CAD just to reseat the original seal and go around it with polyurethane sealant. They suggested not getting a new seal as it would probably not seal anyway apparently.

Seems rather a lot of money to me. Any thoughts? Should I just clean it up and attempt to seal it myself?

Thanks!

Their charge is excessive. A new genuine MBZ Seal will probably cost around $150 if available. The installation cost will average $150. If possible do not use an after market seal - most of them do not fit correctly.

Thanks for the insight. I'll check out my local Benz dealer and see what they can do. The parts desk is generally very helpful and down to earth :)

Hopefully got it sorted. Basically just sealed the leaky seams myself with polyurethane... $8 instead of $300. I'll take that :)

My $0.02...Ask anyone doing the seal replacement if it comes to that, have you personally done this type of windshield before? If not, run. If yes, respectfully ask them how they do it. If that bothers them, run.

There is a factory recommended step-by-step procedure to do this job. I've done it and it works very well. Takes 3-4 hours and is an experienced DIY level task. Taking time and doing it yourself as per the factory procedure will likely result in a much better result than an inexperienced on this type glass pro learning on yours.

I'd use a factory seal if you can find one.

It is common for them to leak down low in the area under the grills on the cowling between the hood and the windshield. Remove the grills and look for any perforations.

Good luck!!!

If you have had that leak for a while, you will probably find a rusted window channel under it. In that case a new seal and/or gobs of goop is a temporary fix at best. Repairing or replacing a window channel by a good body shop is less expensive than you may think.

I had the rear channel on my 300CD fixed and installed a new seal over that. Five years so far and fixed. I had a glass shop R&R the rear windshield since coupe glass is very hard to find. As I recall, the whole job came to about $450.

do not attempt to remove and replace window seal unless you are an expert ! Unfortunately an external seal will work for awhile but will fail. And as mentioned you may have rust issue. Id she is a daily driver or if you are going to keep her get it done right

Where did you find a helpful, down to earth, MB dealership in Canada, or for that matter, anywhere? Most of them hate old cars and I passed on them a long time ago.