Rusted engine block

Scrape off the rust, using a wire brush or scrubbing pad. This technique removes small rust. GM MDI
Apply a rust remover, using a steel wool pad or paper towel. Rub the rust remover into the rust.
Wait 10 minutes for the rust remover to work. Most rust removers contain hydrochloric acid, oxalic acid or other strong acids that dissolve rust.
Clean away the rust remover and the rust with paper towels. Dampen a paper towel, and wipe the areas, again.
Paint on a primer with a paint brush. Let the primer dry. The automotive primers offer protection against rust.
Use touch-up paint that is the same color as the Ford Galaxie. Apply it to all areas that are missing paint. Let the paint dry, before driving the car.

If this is an alignment rod Bar that you are talking off that goes back to the lower arm and the rust is in that attachment point where it is mounted to the frame Then it can be repaired with a new section being welded it but you will need an accredited welder / panel beater to do the job . If it is rusted through the frame then have the whole frame checked because rust is not always visible until the paint is disturbed. This part is vital to the steering stability and if not done properly will result in serious injury to the driver and others.

Considering your car is only worth $5,000 in great shape, I don't think it is worth repairing a rusted out frame and under body. If it was a 72, I would say yes, but 81, ahh, My brother used to restore cars, I saw what he went through, buying and selling his cars, He stopped buying rust buckets, if they had one spec of rust, he didn't touch it, there are plenty of rust free cars out there, And repairing rust is a nightmare, your Mercedes is not like a Chevy where they have every panel in stock ready to weld in, You would need to hire a body man full time for a year to get those panels fixed back up, and get it done on the frame??? Forget it, the frame is probably shot. Painting the undercarriage will take most of your money, you will never get it back out of the car. Hope this helps.

Rusted frame repair is a touchy situation.
Depending on what area of the frame is rusted, the saftey concern can vary.
If your a DIY preson, you can elad on some repair plates to cure some problems.
If it's in an area where a suspension part or steering component mounts, then repairs are touchy.

That "mud" is actually rust. Back in the early eighties the EPA began mandating more and more MPG. Quickest and easiest way to begin doing that is to cut down on the vehicle weight. Engine block and cylinder head castings were made thinner and the use of nickel (which is heavier than steel or iron) in the alloy they are cast from was cut back. Nickel acts as a rust inhibitor and also helps as a "binding agent",
(without that nickel in there, blocks rust easily, reacting to the acid buildup as antifreeze deteriorates. Blocks and heads are also more prone to cracking as the nickel is very important, helping hold the iron together on a molecular level.
Flush the block really well, have the radiator flushed separately or it will plug up worse. I have seen some engines that were so badly rusted that the welch plugs needed to be removed to let the rust out. Or, replace it altogether.
Best thing you can do is change the antifreeze and do a simple water flush at least every two years.
If you don't you will be right back in the shop doing this same repair again!
OK, class dismissed!
Good luck!!

It is under the vehicle under the drivers side frame rail.It might be rusty and hard to remove.Use P.B.Blaster it works really good on rust.Let it soak a little.This is a rust penatrent.Hope this helps.Good luck.

Rust Check once a year. The green can is thicker than the red can but is the same thing. Sprayed by a dealer, they warranty against rust. You should be able to get it at any auto parts store. Hope this helps.

Wire brush the area off and vacuum up any debris. You can use "rust killer" on the rusted surfaces and then use fiberglass mat to repair any holes. Overlap holes by at least 5" wherever possible. You can leave this unfinished or use spray bedliner paint to further seal the deck. i also recommend you go underneath and remove any loose rust and spray afterward with rubberized undercoating or rust will continue to form there. When using fiberglass on flat surfaces you can lay mat down dry and just pour resin on it and smooth it out so resin penetrates and you don't have lumps.

The frame, or just the body? A rusted frame is dangerous specially if it has holes. Welding on them is not recommended cuz it will make the metal hard and brittle. You can't do anything with a rusted frame with holes on it.

something wrong happen after that? u can start your engine?if its only wetness issue so take it to rust washing or by the rust material and wash the car by yourself