Author Topic: 1974 450SEL Rain Leaks  (Read 658 times)

Mergyver

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1974 450SEL Rain Leaks
« on: 28 September 2018, 06:28 AM »
I have been chasing a driver side leak without any luck. Hoping you guys have some advice.

Driver side floor, It seems to be coming from the side right behind the support that the carries the attachment bolts at the front of the front seat. I am thinking door seals but I am not sure.

The foot well in front of those mounting points is not wet. The carpet on the side behind the mounting point feels wet.

I notice water on the rubber boot where the rear door retaining strap (the metal strap that keeps the rear door from opening too wide) enters the B column. I am wondering if water could be leaking through that into the B column and out the bottom on to the floor. Could that be? Would replacing door seals help?

Thanks guys
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

daantjie

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Re: 1974 450SEL Rain Leaks
« Reply #1 on: 28 September 2018, 07:56 AM »
Water leaks are a pain :'(

Problem is that where you see the water does not mean that this is where it is coming from. What I would do is to pull the driver side carpet (the heavy insulated one), as well as remove the driver footrest and really check this area for rust/water.  Then with all this removed, run a hose so that it continually runs water over the driver side of the windshield and then follow the drain path. Do this for at least 5 minutes.

A very common leak is a rust hole under the fuse box which usually rusts through the firewall which then leads to water running down the firewall and collecting in the driver side foot well.  If you are parked on an incline then the water will pool towards the cross member where the front bolts for the seat attaches.  In bad cases it will also run towards the driver side passenger foot well and collect there.

A problem with the heavy insulation in the floor pans is that they hold water really well, no way to dry them out other than towels and to let the car dry in the sun, a real mess >:(

Also check your sun roof drains, this is also a big culprit.  If they are clogged or the pan is rusted out, then the water will not drain properly and find all kinds of channels to make it into the cab.  Oodles of fun :o
Daniel
1977 450 SEL 6.9 - Astralsilber

Diesel 617

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Re: 1974 450SEL Rain Leaks
« Reply #2 on: 28 September 2018, 11:30 AM »
How is the windshield seal, have you driven the car in a heavy rain? Look at the bottom corners of the windshield, water loves to pool their and leak under the seal into the car. Quick test with a garden hose, car wash or a heavy rain.
1980 300SD Retired
1979 280SE Euro Spec Import Crank Windows and Cloth Seats


Inventory Price
1980 450SEL/SE 722.004 Trans 150kmi ($50)
1978-1980 300SD Trans 260k mi $50
-2 450 Pairs + 300SD pair bad boots Axles $25/45
-3.07 450/300SD Differential $30

Mergyver

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Re: 1974 450SEL Rain Leaks
« Reply #3 on: 28 September 2018, 12:04 PM »
Thanks guys. I will start pulling up carpets and see what I find in the driver footwell.
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

floyd111

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Re: 1974 450SEL Rain Leaks
« Reply #4 on: 28 September 2018, 04:50 PM »
On that note, would it be advisable to drill 1 inch holes in each floor pan, with a rubber plug in them, to avoid such mishaps in the future, make them easier to dry?

gavin116

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Re: 1974 450SEL Rain Leaks
« Reply #5 on: 29 September 2018, 12:35 AM »
Hi Mergyver

This may give you some idea of water leaking into the cabin. Occasionally my driver's seat cushion was damp. I never even knew that the foot carpet was wet on the passenger side...

https://forum.w116.org/test-drive/my-first-w116-here-at-last/msg101522/#msg101522

Always try to get the car water-tight, as leaks lead to rust, rust leads to death :(


Randys01

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Re: 1974 450SEL Rain Leaks
« Reply #6 on: 29 September 2018, 01:31 AM »
Whether the W116 is LHD or RHD, the rusting phenomenon on the lhs of the car seems a common problem. In lhd, the fuse box gets in the way of a clean sight observation of how the firewall and inner guard mate up: but in a rhd variant it is plain to see there is a design faux pax which allows water to be trapped in an unsealed seam. In RHD countries, parking aggravates the problem because of the road camber.

Had MB filled these seams with bog, the problem may have been allayed altho ultimately, even the best seam sealer succumbs to frequent wetness.

If MB ever twigged to this design fault, they never remedied it in later production -wherein a small drain hole would have saved the day.
I understand W123 share a similar fate.

I am not aware that the RHS of a W116 mirrors the lhs problem, nothing the way this side of the car is pressed is quite different.

There are plenty of photos on different sites showing how rampant this corrosion can be, often requiring major surgery as the firewall skin is double skinned in sections.

gavin116

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Re: 1974 450SEL Rain Leaks
« Reply #7 on: 29 September 2018, 01:45 AM »
Randy you're spot on! When we did my bodywork, we placed just such a drain on both sides for good measure. See the first two pictures of this post:
https://forum.w116.org/test-drive/my-first-w116-here-at-last/msg122884/#msg122884

Squiggle Dog

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Re: 1974 450SEL Rain Leaks
« Reply #8 on: 29 September 2018, 12:06 PM »
Randy you're spot on! When we did my bodywork, we placed just such a drain on both sides for good measure. See the first two pictures of this post:
https://forum.w116.org/test-drive/my-first-w116-here-at-last/msg122884/#msg122884

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Heated Seats, 347,000+

Mergyver

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Re: 1974 450SEL Rain Leaks
« Reply #9 on: 12 October 2018, 03:45 PM »
Thanks for the pointers everyone.

I have found two leaks. One is a little pinhole of rust under the fuse box. I have not started on this one yet. I am not sure whether it makes sense to cut it out and weld in some new metal or  if I should just clean the rust and use some rust encapsulating paint combined with some mating to temporarily plug it.

The larger leak seems to be coming from the rear window base on the left side. I took out the rear seat and the sound deadening felt mat is soaked from the hat shelf down. The hat shelf cover is also wet. I will go after this one first.

I guess I should start by replacing the rear window seal. I will start a new thread to see if anyone has pointers on that.

1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

ratfink41

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Re: 1974 450SEL Rain Leaks
« Reply #10 on: 30 October 2018, 04:24 AM »
Water leaks are a pain :'(

Problem is that where you see the water does not mean that this is where it is coming from. What I would do is to pull the driver side carpet (the heavy insulated one), as well as remove the driver footrest and really check this area for rust/water.  Then with all this removed, run a hose so that it continually runs water over the driver side of the windshield and then follow the drain path. Do this for at least 5 minutes.

A very common leak is a rust hole under the fuse box which usually rusts through the firewall which then leads to water running down the firewall and collecting in the driver side foot well.  If you are parked on an incline then the water will pool towards the cross member where the front bolts for the seat attaches.  In bad cases it will also run towards the driver side passenger foot well and collect there.

A problem with the heavy insulation in the floor pans is that they hold water really well, no way to dry them out other than towels and to let the car dry in the sun, a real mess >:(

Also check your sun roof drains, this is also a big culprit.  If they are clogged or the pan is rusted out, then the water will not drain properly and find all kinds of channels to make it into the cab.  Oodles of fun :o
Thanks for the info! Do you think it would be due to rusted out rocker pannels. I pulled up the carpet and found a few minor holes, minor as in you couldn't fit a pencil through it. But behind my drivers seat was soaked with water just on the carpets, not the seat.

daantjie

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Re: 1974 450SEL Rain Leaks
« Reply #11 on: 30 October 2018, 01:45 PM »
Holes in the rocker panel (inner) could be caused by the jack hole tube rusting all the way through.  If the rust is in the same area of the jack hole tube then this is for sure the cause. 
Take a good look at the area where the outer rocker panel meets the floor underneath the car.  There is heavy undercoating and it's very common for rust to form underneath it.  You might find a huge rust surprise if you start  poking this area with  a screwdriver.  Peel away the undercoating and you might see daylight :o
Daniel
1977 450 SEL 6.9 - Astralsilber

Mergyver

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Re: 1974 450SEL Rain Leaks
« Reply #12 on: 06 November 2018, 06:15 PM »
I will take a look at the jack points. I have confirmed though that the left corner of the rear window is leaking. I am working on replacing the seal. It is so brittle it is a bit tough to get out.
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased