rust!! - PeachParts Mercedes-Benz Forum

300SD81 · #1 02-25-2007, 06:44 PM

I swapped my chipped rim with a new one I bought today, and my bottle jack punched through the rubber jack pad. I didn't realize that the center of the pad had no metal behind it. It didn't seem to cause any damage except for ripping the rubber pad. But there seems to be a lot of rust on the metal behind it. How would I fix this? I can't see how bad it is without peeling off the rubbery coating under the car. What is it and can I buy more of it and paint it on? Will scraping off the rust and painting be enough?

1ajs · #2 02-25-2007, 06:51 PM

can't realy be fixed find a new jack point.....

as for the coasting it cause more rust then stops it....... if it gets a hole in it anywere then water gets under and it never drys out so it slowly rots... thats probly what happend.. anyhow to fix the rust all you can do is sand blast and peel the coasting out and then get some rust converter stuff or some zink oxide primer then swpray it with caned tar to seal the area...

Mustang_man298 · #3 02-26-2007, 01:16 AM

That jacking hole is supposed to be made of metal, there is no rubber pad, what I think you are seeing is the rubberized coating (supposed to resist rock chips). If you punched through it then chances are the metal's going to be pretty bad. Only thing you can do is peel it back and find some good metal to see how far it goes. You might want to check the whole car over good underneath if the rust is that deep, there may be unseen structural issues going on with more rust, & finding out by having the car come apart on the highway is not the best method...
My 80 has a 2" hole at the front left jack hole, further looking underneath saw hefty rust in the suspension parts and coming out of almost every welded seam in the underbody, I bought a replacement car and the 80 is heading to the "parts department" out in back of the shop. The only 2 panels on it that dont have rust holes in them are the trunk lid and hood.

300SD81 · #4 02-26-2007, 03:33 PM

rubber pad on other side:

rubber pad i punched through (didn't realize there was no metal in the center):

Mustang_man298 · #5 02-26-2007, 11:26 PM

Interesting....niether my 80 nor my 82 has those, or places where they might have once been. There should still have been metal there though regardless, gotta support those pads somehow...

dkveuro · #6 02-26-2007, 11:41 PM

Your not supposed to sharpen the jack ram to a point !

.

86560SEL · #7 02-26-2007, 11:48 PM

I do not have those pads on my 85' W126 (380SE) either, nor any place where they should be.

My car is very solid at those areas.... let me sell you my car and you drop that diesel down in it.

I agree--- that rust looks nasty there. I see you are in Atlanta, so I am assuming that the car spent a good deal of time up north.

I am confused though... you said "punched through". Did you place the jack on the lower part of the rocker panel? The jack is supposed to have a rod that goes into that hole. I do not see how it could punch through it.

Quote:

Originally Posted by Mustang_man298

Interesting....niether my 80 nor my 82 has those, or places where they might have once been. There should still have been metal there though regardless, gotta support those pads somehow...

MS Fowler · #8 02-27-2007, 06:57 AM

My '82 300SD has the same type of pad under each jack point.

dannym · #9 02-27-2007, 08:35 AM

Quote:

Originally Posted by MS Fowler

My '82 300SD has the same type of pad under each jack point.

Same here

300SD81 · #10 02-27-2007, 03:10 PM

I have no idea about the history of the car. I bought it as a $300 beater, and fell in love with it. The jack that punched through was a bottle jack witht he contact surface having an approx. 1in diameter. There is NO rust showing in the pictures, that is dirt, all the metal is covered by a rubbery coating. I assumed those pads were for jacking with non-stock jacks. Maybe I was wrong. All 4 pads seem to fit into a hole in the metal the same way the one I punched through did.

300SD81 · #11 03-11-2007, 05:56 PM

Heres some pics of the rusted area after I peeled off the undercoating. It seems to be localized to the area around where the jack pad used to be. I guess water got in there and stayed there for a while... I'm considering pulling off the pad on the other side to check it, but where can I get another pad?

vtmbz · #12 03-11-2007, 06:13 PM

I'm knee deep in this issue right now, and will share a picture:
This is your jackpoint with the outer rockerpanel removed.

To renew my jackpoints, I removed the rocker panel, and cut away the rusted bottom of the jackpoint

and cut a new bottom: on my car this meant I had to form a 2"dimple in the center of a piece of steel about 6" x 12". weld that to the bottom of the jackpoints extending down under the belly pan, and then replace the rocker panel.

But I have a solid set of jackpoints, and a new rocker panel. Ok, the tools to do it cost more than the estimate to replace.. but I still have the tools!

I would say that when the jack wont pick up the car without going into the rocker, the kind of undercoating is immaterial...

300SD81 · #13 03-11-2007, 06:23 PM

Mine probably isn't nearly as bad as yours is. The area in those pics where the undercoating is peeled off are the only rusted areas. I stopped peeling when I saw clean metal. Can I just sand off the rust there, and put more undercoating on? Is it possible to make metal thicker, without cutting away anything, like melt some steel in to thicken it, without cutting it off and putting a sheet there...

Matt L · #14 03-11-2007, 06:41 PM

Nope. You have to cut out the rusted metal.

MTUpower · #15 03-11-2007, 07:00 PM

Men- he has said he used a BOTTLE JACK- not the standard MB jack. That right there is your first problem- use the MB jack from now on. Second, fix the "pad" (which is there to protect the car when it goes up on the lift, not so that you can use a bottle jack) as best you can and live and learn. Rust is cancer.