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6.9 sill replacement project

Started by s class, 12 September 2007, 02:58 PM

s class

OK as I've said at various times, my 6.9's left sill is in very bad shape.  The right hand side on the other hand is completely free of rust. 

Its anybody's guess why this might be so, but my impression is the left sill must have acquired its denting a long time ago, allowing moisture and dirt to get in.  See the pictures.













[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

As you can see this is an ambitious project.  Accordingly I have bought a new outer sill.  The bulk of the challenges lie in the area around the front jacking point where there is a lot of denting that has extended into the inner sill, front floor area, and chassis rail. 

My intention is to cut away part of the floor on the front left, so as to be able properly remedy the inner sill and chassis rail in that area.  Once the floor is rewelded, I will start on the outer sill. 











The last picture of 'elongated washers' are the bits that go around the jacking points where they exit the outer sill. 

I am somewhat undecided if I should attempt this job before the roadworthiness inspection as it is going to take a lot of time to do it properly.  Something must be done before the inspection though as it will not pass in this condition.

Ryan


[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

nim205

Good luck with an ambitious project!

What I always wondered was, how do you rust-protect the inside of the replacement sill (or any other enclosed space for that matter)?

My logic says that if you weld the new part from the outside, and paint it nicely, it will look good for a while, but then probably start rotting from the exposed metal left on the inner part of the weld.

CraigS

You use a product called Tectyl. This can be diluted and sprayed on and into channels, box sections, etc. and always remains "sticky".



Quote from: nim205 on 12 September 2007, 06:47 PM
What I always wondered was, how do you rust-protect the inside of the replacement sill (or any other enclosed space for that matter)?

[url="http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/"]http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/[/url]

nim205

Thanks for the answer.

I've found Tectyl (#10 in the following link), which is a line of products:

http://www.valvolineeurope.com/pi_sheet_center/index.asp?p=/public/10.%20Tectyl

The most suitable appears to be a substance called Superwax. Still the question remains: do you spray it before you weld in the new panel? wouldn't it then burn away at the welding site or reduce weld quality? or do you spray it after the welding is done? how?



This is the underside of my car. I believe the sill is the original one, since the car is virtually rust-free. A mastic-like product has been applied to the joining of the sill with the floor pan. It is clearly different than the undercoating. What is this substance?


CraigS

#5
That is normal body underseal. Tectyl is applied after repairs/restoration. It can be applied by brush, but is better diluted and sprayed into the chassis and panels so that you get full coverage. I have seen this stuff after 25 years and it is still pliable. It is primarily for internal use - inside box sections, chassis rails, door panels, etc.
[url="http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/"]http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/[/url]

koan


Please takes lots of photos and notes s-class, as this is job that I need to do or have done on one of my sills. No where near as bad as yours, just a bit of rust around the jacking point but who knows what's inside.

Is the sill an M-B part or is it from elsewhere?

koan
Boogity, Boogity, Boogity, Amen!

500eguy

wow, this does look like a very difficult project, but will be great when finished.... my sills seem to be in decent shape... i think one side is patched up a bit, i am going to coat it with POR-15 a rust preventative and hopefully that will solve the problems that could lurk in the future.

s class

koan the sill is a genuine MB part, ex-Germany.  It is labelled with the old style MB stickers, indicating its been a long time on the shelves.  It was actually not particularly costly, ans hence I didn't even think of looking elsewhere. 

I will probably delay this job till after the roadworthy inspection because further investigation suggests there may be problems in the A pillar base as well - in other words this job is going to take a long time. 

But I think today must be christmas - my new welder arrived in anticipation of this job.  50 to 250A inverter-MIG.  Photos tomorrow!  yippeee!


[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

styria

why would blue be difficult to keep clean - or rather any more difficult than other colours?

I agree there are worse things than blue, but either way the colour isn't by biggest concern right now


[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

Well no actual progress on the sill yet, but I got a new toy that I am really excited about, that will help in the project. 

50-250A, DC-inverter MIG.

THis is a nice MIG machine.  Really controlled and smooth welds.  (excuse the other untidiness in my garage.  I do try to keep it tidy, really I do.)








[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

CraigS

It looks fairly similar to one that I have, but which I use gasless. I don't know if it is the same in SA, but in Australia you can only rent the gas bottles, and they charge you a monthly rent as well as the fill up cost. To have it sitting around the garage for those odd occasions when you want to use it becomes damn expensive with the rental.
[url="http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/"]http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/[/url]

s class

#12
Yes the cylinder is rented.  The rental is only ZAR40, or about Aus$6,50 a month.  Nothing.  At that price I can't even pay petrol to go and hire one for a day. 


[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

Today I got the end piece which closes off the front of the sill area :





[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

OK what the new bits I bought do not address is the rusted out front jacking point and the inner sill which is damaged in that area.  So today I received a 'section' of 280SE which will be disected to yield the necessaries.  Photos to come.


[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