My 1989 300E is in perfect operating order and absolutely no rust until I recently inspected the 4 jack points. 3 of the 4 show rust and one appears serious. I'm angry for not having checked more frequently but can't lament over things I cannot change.

I have done a search on this and have found that this is not uncommon and that some owners remove the jack points altogether and fill/cover/repaint the damaged area with new bodywork. This makes sense from the perspective that the MB jacks are not necessarily the best choice for the safe jacking of your vehicle. However, my first choice would be to repair to original condition as the rest of the car is fine.

I have posted a few pictures of the LF jack point (the worst one) and would be grateful for information on the MB body structure around the jack points, assessing the damage, stopping the corrosion, and then repair. Also info and sources for getting the right tools, chemicals, and parts. I was not able to find out the body structure on my MB repair CD's - Is this info elsewhere?

Necessity dictates that I have to do as much as possible myself and limit the most complex work to others.

Many thanks,
Paul

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The inside structure of these consists of a tube (which is open to the elements, shown in pictures) and some reinforcing webbing that allows the weight to bear on the inner pressed 'frame' member and the rocker 'cylinder' along the bottom of the body. Try using the jack in each tube, and if you can lift the car without the tube inner webbing collapsing, which will be evident as the weight will push it upwards and start twisting the rocker outer skin, you're good to go for a cosmetic fix.
That would be a stiff wire brush chucked in your drill or grinder to remove all the rust and paint around each hole. Then treat the area with your favorite rust treatment compound, prime, then apply some rocker panel 'gravel guard'. Finish with spray touch-up paint. All this is well within your skill set, I assume, and not at all expensive. One trip to the local body shop supply should get you all you need for under $50.00.

__________________
1986 560SL
2002 Toyota Camry
1993 Lexus

I think that the rust is generally cosmetic but the worst should be limited to deeper pitting. According to the dealer the rocker panel is a one piece unit and if damaged or severely corroded the recommendation is to replace the entire unit to maintain structural integrity. This must be a very expensive choice!

After talking to a few hotrodders it appears that the best option is to use POR15 "silver" which can be used as a bit of a filler if the area is badly pitted. So I've ordered the starter kit and I'll wire brush the area and use the kit to clean and cover the rusted area. I hope that there will not be any compatability issues between the surrounding metal and paints with POR15 - anyone know?

As this area of the car has an undercoating - is it effective to blend the repaired area with the rest of rocker panel? Or should the entire rocker panel be redone? I presume that the undercoating material is still available. Would this be a specialist application?

Thanks,
Paul

My old school method:

1. Wire brush and grind back paint 2X diameter of rust you see.

2. Use a rust reducer (phosphoric acid type) that will cause a reduction reaction to any remainung pits of oxide. It also etches the metal nicely to recieve the paint.

3. Paint with a water cured urethane (POR15). The silver is thick and is great as a "primer".

4. POR15 can be painted over with enamel, laquer or urethane. For outdoor use a topcoat is recommended. I'd use a chassis paint that matches your color scheme and paint the whole rocker panel (I've actually used a brush on some friends' cars for this.).

This site is for a proprietary brand of water cured urethane, but it applies to POR15. http://hirschauto.com/miracle.htm

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

OK, I've wirebrushed the rust away (first two pictures) and then ground most out with a small grinder on a Dremel tool (last two pictures).

There are still small rust pits in the metal and some rust in the weld joint at the 12 to 3 o'clock positions. The POR15 is supposed to neutralize the rust in the pits - right? What about the rust in the weld joint? Or should I grind out the rust in the weld - I assume that it wouldn't take much more grinding to remove it. The instructions with the POR15 state that it is OK to have some rust remaining but I'm not so confident if the rust is migrating through a seam or joint. I do want to do an excellent job so that I can rest comfortably with my results.

It also looks like that I will not need the POR15 Silver as I didn't have to grind out too much. However, I am thinking about blending the repair to the existing primer/paint/undercoating - is this doable with an excellent result or will look it like a patch? This is the part that I'm worried about as I want to do a "perfect" job and not have to re-visit this anytime soon. I changed my thinking because it looks like the weatherstripping between the rocker panel and door is glued on and may be a big hassle to remove or replace in order to permit a thorough repainting of the rocker panel. Same concern goes for the rubber pads beneath the jack posts.

My other concern is the rust inside the tube. The tube corroded as deep as the plugs. Based on your previous comments and from what I can see inside I think that the best action is to use POR15 black paint after I brush/grind out the rust. However, I am concerned with the compatibility of the POR15 and the MB coating inside (is this WAXOYL?) as well as blending the two coatings so that the tube is full protected inside. Your comments?

Again, thanks for your tips and I'll keep posting my updates with pictures.

Regards,
Paul
1989 300E

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First of all, EXCELLENT start! Looking really good here. Since the Por15 kit is on the way anyway, just use it to finish up the preparation.
You could get one of those small diameter brush-type attachments, or use a cylindrical sanding attachment, to ream the worst rust out of the tubes, then apply the por15 inside and around the holes.
Jbaj007's advice is good, re. the rust reducer, as an alternative to Por15. I'd wait and read the Por15 directions as far as compatibility. It's likely one or the other will work nicely, since you only have surface rust (and little of that now).
So, having finished the first stage, you now need to examine the finish of the rest of the rocker panel, to plan the blending. Your pics don't show the texture of the surface of the rest of the panel, but it's likely a gentle pebbly effect from a thick coat of whatever compound Mercedes used to undercoat the paint.
I found spray bomb rocker panel coating (not undercoat), like GravelGuard, is fairly close to what my old MB had on it, but yours may differ. You need to find a similar coating to do an effective blend. To make the repairs disappear, and avoid refinishing of the entire panel texture surface, it's essential to get the right stuff under the paint.
Then, it's time to decide whether to repaint the entire panel, or just the repaired areas. You needn't remove weatherstrippng and jack pads, just do a good masking job. If you are going to repaint just the repairs, mask out about 1" beyond the repair, turn the edge of the tape up about 1/4", and spray over/from behind the turned-up edge (like 'over the fence'). This trick helps to avoid a buildup of paint at the masked line. Of course, mask EVERYTHING all around the areas you are working on to minimize overspray.

__________________
1986 560SL
2002 Toyota Camry
1993 Lexus

Use POR15 on my sons 65 Mustang. The POR15 does like a rough surface with some pitting. It really likes to adhear to that kind of surface. Use the 3 products that are recomended by POR15.
The first step is the Marine clean it is a strong degreaser that will remove any grease. It will burn slightly on the skin, As I said a STRONG degreaser.
Second step, Metal ready. A phosoporic acid/ metal primer soulution. apply it and allow it to sit for a while. It eats away at the rust and converts it to carbon. After evaporating it leaves a metal prep on the surface.
Then apply the POR15.

You must follow the companies directions, by using all 3 products, or the por can lift off the surface.

Some findings.

A rough surface is better. Don't worry about eliminating all the bumps and rust.

Cover yourself completely when painting with the POR15 paint. If it gets on your skin and dries, you have to wear it off. Just like Gorilla/polyurathane glue. So cover yourself. You can use ther cleaner to remove it if wet. Once dry its there until your skins top layer dies off. A note. You can use 3M weatherstrip adhesive remover to remove it when wet. It takes a little more but works nicely.

I'm more concerned with the interior of the rocker panel. The tube goes all the way thru and you have a cavity that may or may not have rust. If the metal seems solid and the rust has not eaten thru the rocker panel and tube then you should be OK. POR15 it and touch it up. If the rust shows it has eaten away at the metal and is allowing moisture into the rocker panel then you have a bigger job in front of you.

Let us know how it goes.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

I started the POR15 process but was not comfortable with the results after using the METAL READY. By then my time had run out and other priorities were calling. I went through the instructions again and also called Customer Support so I think I have a better handle on what to do next time.

In the mean time I was curious about what Mercedes demanded for surface rust repair and was essentially told that it depends on the paint manufacturer. Since this car was prepared/painted with Glasurit products I tracked down a local contact (Glasurit is owned by BASF) and he was fairly helpful. These are the products he recommended to follow closest to OEM metal preparation and painting:
Glasurit epoxy 801-1871 (used by MB on bare metal for warranty repairs)
Glasurit HS Primer 285-50
Glasurit Stone Chip Protection 1109-1240
Glasurit 55 Line base coat
Glasurit 923 series clearcoat

The rep couldn't recommend POR15 because there is no knowledge of compatability with Glasurit and that it is not a Glasurit product. Another auto enthusiast friend also suggested that I stay with an epoxy repair which, I assume, implies to not use POR15.

So I have a dilemma. Using the POR15 process looks like a job that I can do myself but will likely not match OEM or meet long term corrosion protection needs (unsure of compatibility with surrounding paints and anti-corrosion coatings). The Glasurit/epoxy approach appears to be more complex and more expensive (ie body shop) but offset with more long lasting and better visual results (compatible with surrounding coatings and using well-researched products).

What more should I find out? Are my assumptions correct or am I misleading myself? Your comments?

Thanks,
Paul

I'm not an MB expert but from years of restoring old cars I'd say it depends mostly on the environment you drive the vehicle in, and what degree of "correctness" on the car you are willing to accept. In my experience, a urethane like POR15 will provide better long-term protection vs. an epoxy against rust in severe conditions, such as driving on salty, snowy roads. You can paint over POR 15 with modern auto paints.

I would not worry about compatibility with any waxoyl-based products, IMO it's long gone on any exposed surfaces you are about to recoat. (unless they have reformulated it, Waxoyl was just a mix of oil, turpentine and wax...)

But of course MB didn't use POR 15 when they first built the car, so using it is a non-factory modification if you look at it that way. If it were me and I lived in Wisconsin or some hellish place like that and drove in winter, I'd use POR 15. If I lived in southern California I'd refinish with factory paint.

I would heed the previously-stated advice to check the surrounding metal for damage also, and if you do decide to apply the POR 15 yourself be sure not to get any on you or anywhere you don't want it to go...

__________________
1999 SL500

Request current pictures, how is the repair holding up to Canada winter?
Any special advice on this repair?

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Well, in the end I chickened out doing the repairs myself after losing confidence with the products from the local auto supply store and also not having the right environment to do the job properly as it was getting too cold outside. So I prepared the jack points as shown and did what I thought was right for prepping against flash corrosion. I also called a few autobody shops and then choose to take the vehicle to the only local shop that used OEM (Glasurit) supplies. My stipulation was that I never wanted to return to the shop with the cost chasing that requirement.

However, I'm not sure that I received what I wanted.....take a look. Any comments?

Appreciate any thoughts on next steps.

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Exterior is nice.
Interior looks like naked metal.
You could attempt POR15 treatment, but you risk making a mess of the exterior paint.
Several members use bearing grease inside the tube + a rubber plug/cap to seal each tube. With the correct cap/plug it looks good, and will out live the vehicle, the only issue becomes heat = poor cap/plug seal drooling/leaking grease during hot summers = visiting Texas, Mexico, Florida, southern California, etc, etc.
In Canada you should not have heat issues, so I would suggest a light coating of spray chain grease = farm equipment or motorcycle shop should have it, the cap/plug may be more difficult = to find one that fits correctly, and you can buy in groups of eight or more for spares.

Please do NOT pack them solid with bearing grease = in (Canada) sub zero conditions it becomes very hard, making the jack point unusable.

I still have the original caps. I left them off as others were saying that the caps only trapped moisture inside and this was the cause of the corrosion in the first place. All 4 jack points had grease remaining with 3 of the 4 having corrosion at various stages. The corrosion was limited to the first inch or so inside the tube and the worst corrosion appeared to be at the outside edge.

I'm worried that putting the caps back on would start the process over again. Your idea of putting the POR 15 on the new corrosion seems logical although, as you say, care would have to be taken to avoid damaging the paint. I hope this would stop or substantially slow the corrosion.

Thanks for the response! I also appreciate all the others who have guided this repair.

Paul

I really do think that you should replace those caps. In place, maybe with a bit of grease or dab of silicone to seal them, and assuming you have now sealed the tubes on the inside, the only moisture in there would be condensation....and we know that it takes warm/cold surfaces to produce this, highly unlikely inside a rocker panel IMO. Leaving them open just gives the water a 100% chance of getting in, and in our winters, you'll maybe get some salt in there with it too.
If you're worried about grease stiffening up in the cold, just get a small container of snowblower grease, the kind they use in the differential, I think it's called Alvania or something like that. I used it on the regulator gears and tracks of two of my Mazda power windows to keep them from slowing down in cold weather due to stiffening.

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1986 560SL
2002 Toyota Camry
1993 Lexus

How about doing both. I think whunter's suggestion of the spray chain grease is a good idea, but what about combining that with putting the caps back in with one minor modification---center and drill a tiny hole in each cap so that water can wick out if there is condensation that develops or any water happens to "splash" up in there. Then I would think you would have the best of both worlds. Just a thought.

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1986 300SDL
1988 Monte Carlo SS
2002 Avalanche
2003 100th Anniversary H-D Dyna Wide Glide