Recently I noticed that two of my rocker plugs are missing allowing road water to be sprayed up into the rocker. My rockers are currently rust free and I would like to keep them that way. I would like to clean, dry and re-rust proof in there before I replace the plugs. I am told that they came from the factory with a waxy rust coating sprayed in. Any body have any suggestions for cleaning in there and re-applying the rust proofing?

Thanks.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Hmm... I thought we had this very discussion a few days ago. I seem to recall suggesting the use of Waxoyl to duplicate the waxy protectant, but my search on the term didn't show up.

I'd love to hear some too as it is already a problem on my car....

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'83 300D Turrrbo 295K miles

Home made "waxoyl"

2 1/2 qts turpentine
12 oz bee's wax/candle wax
1 qt light machine oil

-shred or grate wax into turpentine slowly, mixing to dissolve (GENTLY warm if necessary - NO OPEN FLAME)
-slowly add/mix oil in until thin enough to be sprayed (leave slightly thicker if brushing on)
-reapply once per year.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Mixture of petroleum products like grease and oil is vastly superior. If there is even surface rust in there it will slow it down almost to a halt. Anything else to my knowledge will speed it up. Spraying the petroleum mixture in is fast and easy. Drill half inch holes in the bottom of the rockers and use cheap plastic plugs available at most auto parts places. Warm it up first of course. I dealt with corrosion engineers and dealt with corrosin problems years ago. Any other approach is almost hopeless in my opinion. Especially in a closed in area like mercedes rocker panels.
Unless you want to spend a fortune initially or have clean absolutly unrusted metal to start with. Many times you can increase the rate of oxidation rather than slowing it down. I spent a lot of money learning this the hard way and have seen enough over time to believe it.

These rockers have holes (plugged) from the factory. DO NOT USE GREASE!!!!!
IF you do have perfectly clean metal, start with a zinc chromate primer (124 bodies were galvanized) or any primer rich in zinc. Works well short of sacrificial electrodes (IE: ocean going boats)

Already rusty? Oil with a solvent carrier is best. WHY no grease?

LOTS of research (NASA, USA Corps of Engineers, USN) found, repeatedly, grease does not move by capillary action, it sits still and forms a seal trapping what ever dirt, moisture, air, old rust etc. WITHOUT displacing it from the metal you want to protect.

Recall a mountain gondola falling when the cable broke in France about 14 or so years ago? The mechanism of failure was that over the years of service the cables were GREASED and not oiled. Corrosion progressed from the core - outward because moisture was trapped under the grease.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

We did, but on another forum. I thought I would see if I got any other ideas from a different audience.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

First I guess I need to look in there and see if any surface rust has formed.

What could be used to thin down oil to spray it in there, and what type of oil should be used (motor, 3 in 1, WD 40...)

If the existing factory waxoyl coating has prevented rust from starting should I try priming with the primer mentioned above, re-apply some waxoyl or just dry and re-seal the rocker?

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

The grease thckens the oil a little yet still allows the oil component to creep all over the place. Of course there will be existing rust in there other than in places like arizona.
Any topcoat over rust does seem to speed up the rate of oxidation compared to oil. The moisture becomes trapped or the existing oxide is still free to aquire oxygen. I am not talking about new metal here but what exists in reality. The oil seems to saturate the oxide to the extent of very little oxygen is able to get through to it.
Remember we are talking about a semi sealed box assembley here so you cannot clean it down internally prior to any treatment. Or really even get a good look inside it. Waxoil and it's kin just primarily lay on top of the oxide. Heavy grease alone would tend to do the same. But that option is meaningless anyways as you have no way to get it in there. Heavy grease and waxoil products are designed for new metal application basically. The oil component has to be able to creep as it is impossible or very difficult to get complete coverage in there otherwise. It does work extremely well in real life and in testing formats.
We used to buy a product called grease and graphite. In thirty gallon pails. The grease was lightweight. We were able to spray it as we had hydralic guns. At home you are limited to something like a 20.00 schultz gun. It cannot cope with too stiff a mixture. Thats why I know you could not have too much grease in your mixture. Our hydralic guns generated somewhere between 2-4 thousand pounds output to spray it. Remember you are trying to prevent oxygen and moisture from coming into contact with the oxide. The schultz gun is the one available to spray rocker panel rubberized coatings on. Reasonable in price and it will last a lifetime. I would not spray an oil lighter than 40 grade warmed up. It has to remain in place to some extent as well as creep. A lot of products like rustcheck or thin oils will tend to almost evaporate with time. They are poular because of cheap application equipment requirements. Our air powered hydralic guns were probably 1500-2500 apiece when we purchased them years ago. One gentleman was right on about the large cable the heavy grease alone trapped the moisture in the cable causing accelerated rusting. The cable would have lasted longer in my opinion with nothing applied. Waxoil presents about the same senario over rust.

Here in the rust belt we don't drive cars we like in the salt, but for some it's unavoidable.

One thing that we learned in the '80s is that some rust-proofing treatments actually cause more rust. This happens when the rustproofing (kind of a tar and solvent type of spray) forms pockets, voids, etc., and most important is that it would often block the drains at the bottom of doors rockers etc.

A friend of mine would make a spray with oil and kerosene, spray in doors and other voids with a garden sprayer, let it drain and drive all winter. His cars lasted pretty well.

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Gone to the dark side

- Jeff

i know this probably isnt the chaepest solution, but...
what about rhino lining or a product similar to it, i think that with the proper prep and cleaning, that this would work quite well and last a long time.

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82' 300SD

The problem is the prep work. you cannot bury any oxide at all. If the rhino coating stuck really well on spotless metal you probably would be okay. We are talking long term results over many years here.

The problem, like barry stated is cleaning the area through a few holes.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

How about POR-15 thinned & sprayed with a curved wand? I'm a firm believer in this stuff. Once it hits rust, it's not coming back. Of course, the rust has to be sound. If your rockers are real bad inside, it would be hard to scrape rust flakes off the metal-my 2 cents, Paul.

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1984 300CD red/blk 290,000 partial resto
1980 240D 4 sp Brn/palomino gone
1997 Mazda Miata STO edition wife's baby
1988 Lincoln Mark VII LSC next resto
1986 Subaru GL wagon daily
1993 Isuzu pickup field beater
2008 Honda Civic EX-L 5sp wife's new car
1978 Honda XL350
1974 Honda XL70 my Calif. ride in HS

Pull out rubber plugs and spray bar and chain oil (yes the stuff that used on chainsaws, it has wax parrifins in it.) and using compressed air and a air gun which is designed for applying chip gaurd to the rockers, spray the oil in the holes at different angles. You really don't have to lay the oil on thick as it will move on its own over time. Let it drip, and if you are creative you can collect the dripping to use again, then reinstall the plugs. Its a little messy but theres one thing metal loves and its oil.

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Currently driving a very clean 1985 300SD from the West Coast.