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Bootwell rust repair

Started by s class, 22 January 2013, 04:43 AM

DialecticDielectrics

I've got the same problem in exactly the same spot.  Seems like there are bunch of us.  Any idea where the water usually gets in? The antenna is on the other side, so it can't be through there.

Body shops are quoting me about $1000 to do the patch work, so I might have to try my hand at this job, although I have absolutely no welding experience  :o.  I take it that it's a much better strategy to find a rust-free piece from a donor than to attempt patch fabrication?

gf

Water usually gets in through cracked  boot seals and tail light seals.  plugged water drains will speed up the process.Usually you dont spot it until rust has eaten clear through cause of the carpets and stone chip protection hide the puddles and rust so well. Nearly every w116 ive seen has a history of this. If your seals arent good and youve a rust free w116- 3 months of rain will do it!
 

oversize

The rear window seal and fuel filler drain is also a problem.  These should be checked regularly.  Patches are fine as long as you keep the original contours (so the repair isn't obvious) and you protect the new steel/welds effectively
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

DialecticDielectrics

This is all very useful. 

One shop quoted me a little under $600 to patch the hole with fiberglass.  Anybody have any thoughts on the fiberglass technique?

Alternatively, if I stick with steel, what sort of power tool would one need to cut out the piece from a rust-free donor car, IF such a car exists?

s class

Fibreglass would be considered a bodge technique.  And $600 is a hell of a lot for a bodge that you can do yourself just as badly at home on a Saturday afternoon. 

A permanent repair requires welding, and importantly, grinding and treating of the welds on BOTH sides afterwards. 

There are many tools you can use to cut out donor panels.  Basic DIY would be an angle grinder, pro stuff would be pneumatic shears and spot-weld removal drills.

I would suggest that this is a difficult weld, even for someone experienced.  You definately don't want to try this as a learn-to-weld-first-attempt.  Thin sheet is very tricky to weld without burning holes.  You can do it with an oxy-acetelene set, or (preferably) a MIG machine (AKA CO2 welding).  If you want to go the DIY route, practice cutting up and welding back together on scrap body panels first. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

ZCarFan

Quote from: DialecticDielectrics on 28 February 2013, 09:48 PM
This is all very useful. 

One shop quoted me a little under $600 to patch the hole with fiberglass.  Anybody have any thoughts on the fiberglass technique?

Alternatively, if I stick with steel, what sort of power tool would one need to cut out the piece from a rust-free donor car, IF such a car exists?

I agree with S Class -- no reason to pay $600 for what you could do yourself for $30.  I've used the fiber-reinforced resin to fill in missing metal before, and have had some last 5 years or more.  In the end, it is still "damaged" but it you are trying to seal up the car and preserve it until correct repairs are made it beats leaving a hole there.


oversize

Stay away from fiberglass.  Do it right the first time and save $$, time and effort
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

DialecticDielectrics

When talking to the guy at the body shop, I didn't realize that the fiberglass job he was talking about would be the same type of fiberglass that can be found at any auto shop.  For some reason, I thought he was describing some sort of more sturdy fiberglass, buuut I guess I was mistaken.  In fact, the previous owner fiberglass-patched this spot, and my impression is that the fiberglass probably made the rust worse by trapping moisture up against the metal and feeding the rust.

My friend has a 110 V MIG Welder and some experience working on jobs like this.  So I think we're going to give it a go with a patch piece.  In the Oregon climate, I think I'd be hard-pressed to find a donor car in a pick-n-pull that isn't also rusted, so patches may be the way to go. 

ponton

I believe the patch panels are still available from mercedes for something like $100. It will come in a factory e-coat so you won't have to worry about whats lurking beneath the surface.  Joe can probably shed some light on the availability situation.

Ian

s class

Left hand side - looked innocent enough from the outside.....



Looking rearwards from the rear wheel arch, the extent of the cutting is evident :



Looking forwards from the rear of the car :



[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

s class

After welding, repaired areas primed, flatted, seam sealer applied, and stone chip applied in the correct areas.  You can see the primer has been feathered out, and the masking is set up in preparation for blending the colour in :

On the right :



On the left :



right side, from underneath, looking forward :



[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

s class



[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oversize

Damn fantastic job!  Love your work; well done!
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

Squiggle Dog

That looks great! I'd like to learn welding and bodywork, and will need to since I have a 1960s major rustbucket project on the backburner.
Stop paying for animal cruelty and slaughter. Go vegan! [url="https://challenge22.com/"]https://challenge22.com/[/url]

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, 350,000+