I am doing a lot of rust repair on my 1971 W109 3.5l: trunk and rocker panels were rusted out. I have also repaired the floorpans which had rustholes.
The car is on stands. I am not driving.
Now: after finishing the trunk and floorpan I saw today lots of water after a heavier rain in both locations. My question is: where is this water coming from??
Is there a chance that water leaks through the front and rear window? Window seals leakin?
My rubber is old and I can see that chance.
Or where do you think the water is coming from and leaking into the car?
Martin

That would be my first guess. I have a similar problem with my 1973 W114. Fortunately I don't have to drive it in the rain anymore. I have the front and rear window seals, but my problem is finding someone that has the knowledge to change them without ruining the trim moulding and/or breaking the window(s). I am a little afraid to try it myself, but some have said if you take your time, it's not that bad. Hope you get it fixed.

Hello,
Window seals are often the cause. In addition, the sun roof drain passes through the "c" pillars and into the trunk before it exits through the trunk floor. Take a look at the condition of these plastic or rubber drain hoses. There is one on each side of the trunk back near the rear firewall.

If all else fails have someone hose down the car while you are closed up in the trunk with a flashlight. You'll surely find the leak this way. Caution, there is no interior latch release in these trunks so your helper will have to let you out!

__________________
Joe Alexander
Blacklick, Ohio
1964 220SE Rally (La Carrera Panamericana someday)
1966 Unimog 404s (Swedish Army)
1969 300SEL 6.3 (sold)
1969 280SL Pagoda
1973 280SEL 4.5
1974 450SLC FIA Rally car (standard trans)
1982 300D turbo (winter driver)
1986 560SEC
1989 Unimog FLU419 (US Army)
1991 300TE (wife)
2002 SLK 32 AMG (350 hp)

I agree with the assumption it's the seals. The windshield and rear window seals in my 108 leak, and I keep it under a cover while it sits @ my parents' house outside, because otherwise the passenger floorpans fill with water! For some reason the driver's side doesnt. It's that self-draining feature that ferric oxide makes!

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

The water may find its way onto your vehicles floor by rust-holes in the empty area under the wipers and behind/above the wiper-motor. The water likes to stay there and finally joints give up allowing water to flow in. The damage is VERY nasty to repair, see the pictures of the work I did last autumn:

And what finally stopped the water leaking in was opening that hollow under the vipers and grill and remaking the joints. Both the drivers and the passengers side. A boat epoxy finished the joints. Problem is that I had to weld the hollow closed again, so the hole there is for applying rust-preventing paint to cover..

Hey Pettery K

This sounds like a serious possibility for water to leak into the interior /floorpan.
I guess that's the problem.
I am doing rust repair for the last 1/2 year now and it is not too shocking any more. I am welding and I use Miracle paint/ fiberglass in combination.

Do you have a quick manual how to get to the area you are referring to?
I guess I have to take off the wipers , take off the panel/ grill between hood and windshield?
Many thanks Martin

Exactly. And that what You see is the cover for the hollow which is very hard to check without opening the top of it using the angle grinder, these parts are welded together:

But try first:
Remove also the noise reducer from the engine room and the viper-motor so that You´re able to see the joints there. Remove the interior plates under the steering wheel ang glove compartment and also take off the drivers seat.
Then ask Your mother to visit and get her watering can along. While Youre lying on Your back with with torch with Your head below the steering wheel ask her to pour plenty of water on windshield. You will be able to see the front leaks, if there´s any. If there are drops coming thru sheets, try a bit with screwdriver and
Then You should also check the engine room side as well, how the water begaves there, again the watering can is useful.

If there´s rust and strongly advice You to remove the fenders also and see the whole area thoroughly!

I forgot to say that´s best to remove the brake booster as well.

Right time to paint the booster and get a brand new master cylinder..

Petteri

Fortunately I have the fenders off already (the idiot before me had welded them to the rockerpanel..and cut off the screw connection there...so I don't know if I can get this screw connection back)
and I also have the covers underneath the dash off.
And I was planning to take the booster out anyway..because there are rustholes under there.
Good plan. I'll remove the panel underneath the wipers where the wiper motor is and the filter for indoor air... and will see what the mess is.

Thanks
Martin

I have seen these drains in the trunk and wondered where the water to be drained is coming from. I understand the sunroof but I have no sunroof.
Is it a drain for the trunk lid then?

I have seen that in the rear between trunk and rear window there is a panel..where the 2 plastic drains on either side attach. I have notice that in the 2 end someone has put epoxy probably to close these drains ...or for whatever reason.
Can you explain how these drains work?
Martin