Rubberized undercoating alternatives? - PeachParts Mercedes-Benz Forum

Mölyapina · #1 12-20-2013, 10:35 PM

What have folks done to replace the rubberized undercoating in the old 'Benzes? I've seen JamesDean complain about how it sags and creates little pockets for water to sit in, and after crawling around underneath my car, I can see where he is coming from!

I found that Advance sells this 3M rubberized spray-on undercoating. Anybody here used it? What have folks here used?

lorainfurniture · #2 12-20-2013, 10:44 PM

I have a pump sprayer from Home Depot and spray my used motor oil under the car.

Mölyapina · #3 12-20-2013, 10:51 PM

Quote:

Originally Posted by lorainfurniture

I have a pump sprayer from Home Depot and spray my used motor oil under the car.

Hm. Do you still have the factory undercoating on your car or have you stripped that out?

lorainfurniture · #4 12-20-2013, 10:57 PM

Most is still there, but rust is rearing it's ugly head. It seems the oil it the only stuff that really stunts the spread of rust. Once it builds up, you don't have to do it anymore.

Rockyriver · #5 12-20-2013, 11:03 PM

I have used the 3M from advance and it works well.
However it runs out quick, that stuff comes out fast.
Wear old clothes and paint it on somewhere you don't walk
Or drive. It splatters a lot and it sticks like mad to all it touches.
Wrap the exaust pipe or put up with the smell of burning tar a few days.
Don't get it on the drive shaft or bolts you may want to take off.
Other than that it makes the car look like new under neath.
Car ramps and having the car off the ground so you can get underneath easily is a big plus to
Using this stuff neatly.

Rockyriver · #6 12-20-2013, 11:05 PM

Quote:

Originally Posted by lorainfurniture

I have a pump sprayer from Home Depot and spray my used motor oil under the car.

Good God that must make a mess in a driveway or parking area.
I never heard tell of such.

Mölyapina · #7 12-20-2013, 11:33 PM

Quote:

Originally Posted by Rockyriver

Good God that must make a mess in a driveway or parking area.
I never heard tell of such.

Yeah, that is done in the other rust belt. There are even shops that do it professionally, but they are thinning out as this becomes less and less necessary on newer cars.

And it works. My parts car 300D looked like someone had dutifully sprayed it in the past, and many of the nuts and bolts -- such as the transmission support bolts -- were easy as pie to take out.

Of course, I was absolutely covered in engine oil after that, bu that is a small price to pay for no rust (the car had plenty of rust as a result of water leaks, but no rust going outside-in).

Stretch · #8 12-21-2013, 04:43 AM

I'll probably use POR-15 and then their chassis top coat.

I know it won't be as quiet as the rubber stuff but if there's a leak the water won't get trapped and travel across the whole sodding length of the vehicle (merrily chuckling and giggling evilly - ha ha I'm really going to %%%% this Benz up). It'll just rust through in one spot.

KAdams4458 · #9 12-21-2013, 04:44 PM

If you're doing an all-over job, Zolatone Tuff Rider is nice stuff. It's supposed to be bedliner, but it's a much better undercoat.

It's a two-part urethane that needs to be applied with a schutz gun. It dries fast to sort of a dense foam finish with a bit of gloss and slickness. It doesn't chip, probably because it has some squish to it, so even rocks bouncing around in wheel wells become quiet and less of a distraction. Definitely good stuff.

barry12345 · #10 12-21-2013, 05:07 PM

Well depends on your climate. In temperature swings the metal underneath the undercoating sweats. Somehow or other oxygen gets in as well. Oxidation or rusting then can be worse than on bare metal.

Petroleum products seem to block the oxygen and slow down the rusting as much as they can. You cannot absolutely stop it other than it's total elimination once underway it seems.

For some reason it is also worse in humid climates. Spraying coatings that set up over rust in general will accelerate the rusting rate. A hard coating well bonded to clean unrusted metal seems to work to some degree.

Other than that petroleum products are known to be the best alternative. Grease is better than oil. Sprayable with crude equipment if warmed up. Messy to do under chassis work afterwords unless steamed off is a problem.

Zulfiqar · #11 12-21-2013, 05:46 PM

The oil attacks the rubber coating - seen that a ton of times, if you really have a problem of the factory coat peeling away, use a steel scraper and some elbow grease to remove as much as possible.

Once done spray the 3M product with utmost care of splattering, wear a full banana suit.

You also should get a can or two of Nuxodol - its the wax coating that is sprayed inside the body cavities, the Noxudol is really thin and will get everywhere in the body. This is how such problems are dealt with in EU.

Using oil is a disaster by any stretch, Ive seen countless cars being destroyed by it.

barry12345 · #12 12-21-2013, 08:16 PM

We have a real bad deal going in the eastern canadian rust belt. Dealer applied harder undercoatings applied at about 400.00 each on new cars. The cars rust out quicker than without any undercoating at all quite often.

For example my son in laws 2002 Honda civic was not undercoated and fared far better than his friends similar cars that were dealer undercoated over time.

Sprayed and touched up yearly with silicon based oil products instead from new properly they do very well in comparison. I suspect thin oil products or the leaching of the oil component in grease ties very tight to the steel denying it oxygen so it cannot rust.

I still have our hydraulic grease and graphite spray set up. You cannot buy the mixture anymore and it is slightly illegal now to use this. It compressed the product to several thousand pounds pressure and sprayed it through a small orfice. We found it quick,fast and effective.

I have always suspected the Mercedes coating was intended as a noise reducer primarily more than a rustproofer. Otherwise I could not see why the factory stuck to applying it. Their cars rusted out really seriously in our climate.

motoxo · #13 12-22-2013, 12:54 AM

i've heard that mb uses atmosit.

terson atmosit

i sorta like the idea of oiling up the iron to deter rust. my car is a rust magnet. hmm ... when it's rusted away it's no longer magnetic so technically that's wrong.

cho · #14 12-22-2013, 06:21 AM

Quote:

Originally Posted by Rockyriver

Good God that must make a mess in a driveway or parking area.
I never heard tell of such.

no it does not it dries and pick a dust ....many folks over here do that procedure..as long is 15w40 oil
used...the procedure is repeated every 5 years or so.... I had a opportunity
to examine some of those cars underneath.... no rust at all...

while spraying the rubber has to be avoided....

but...zinc based coating is the best way to go if you have the means...

.

1project2many · #15 12-22-2013, 10:41 AM

I've got lots of experience and research in this regard. Rust occurs when iron oxidizes in the presence of moisture. If you can remove the moisture or the oxygen you can prevent or stop rust.

Most new cars today are sold with some type of rust through warranty. In order to meet the warranty the car bodies are typically treated with a sacrificial coating to prevent early rust through. The sacrificial coating oxidizes faster than the iron in the steel. Zinc galvanizing is the most common coating that I'm aware of although the auto industry is constantly searching for less expensive, more effective treatments. If you look under a car and see powdery grey-white corrosion on a steel panel then you are looking at oxidized Zinc.

Galvanizing is a good treatment as it can be applied to metal on one or both sides, before or after the metal is shaped, and it can be applied in a separate facility from where the car is assembled. It can be welded through with proper equipment and it has the ability to "heal" if it's mildly damaged. But galvanizing is not effective indefinitely. Once the zinc is depleted the iron in the steel is unprotected and will corrode quickly.

Paint protects metal by preventing both moisture and oxygen from reaching the base metal. To be effective, paint must adhere well to the metal it's protecting and it must be able to fully seal all surfaces which will be exposed to moisture or oxygen. When a panel can be properly cleaned and prepped, and access is available to all surfaces, paint can be an effective rust deterrent. But as an underbody rustproofing applied after a car is manufactured, paint is not very effective.

Rubberized undercoatings are similar to paint. They protect a panel by providing a physical barrier between the panel and the moisture and air which cause rust. Like paint, undercoatings must adhere to the panel they will protect, and they must seal or encase the panel to be effective. Undercoatings are much more viscous than paint and require careful application to be effective. You must have line of sight access to every place you'd like to protect in order to ensure a spray on undercoating treatment will be effective. So if you want the rockers protected, you must drill holes or remove plugs to gain access to the inside of the rockers. If you want welded subframe components protected, you must drill holes in the subframe to allow coating to be sprayed inside the subframe. Undercoatings, like paint, will apply over moisture or water then cure, trapping moisture in exactly the spot you don't want it so application should be done with the car clean and dry... very dry. Oh, and one way to tell if the OEM coating you're looking at is intended to be a rust preventative or a sound deadener is to see if the OEM drilled holes and applied the coatings inside boxed panels and structures such as the rockers and subframe. No holes = ineffective as rust preventative.

Oil has the wonderful quality of having a greater surface tension than water. Panels coated in oil will repel water and will be protected from oxygen. Like paint or rubberized coating, the panel must be fully coated to be fully protected. But unlike undercoating and many paints, oil has a tendency to creep or spread out from the area it's first applied which means it often flows into welds and behind brackets and lines that would be an obstruction to paint or thicker undercoating. Oil spray applied under pressure can also displace water and will creep into areas already rusted to provide protection there. In my experience significantly rusted frames can be slowed to near zero progression with yearly applications of oil. So oil can be a very effective rust preventative but there are some valid considerations before using it.

---Petroleum based oils have a severely negative consequence for our cars because they act as a solvent to the petroleum based asphalt typically used in rubberized undercoating.

---Petroleum based oils have a severely negative connotation in connection with the environment and use of such could result in a visit with local environmental police.

---Oils are only effective as long as they remain on the panel. Since oils don't cure, they generally need replenishing over time.

---Applying oil requires protective gear and cleanup equipment. Petroleum based oil is a carcinogen. Used oil contains heavy metals and unburned fuels which are also health hazards. And it's messy. You really don't want to be taking a bath in the stuff so a protective suit is a darn good idea. And if you apply it with an air sprayer you don't want to be inhaling any vapors so a respirator is important. I've applied oil based spray for menay years and can provide some interesting suggestions on what is more or less effective.

There are non-petroleum base oils, too. Vegetable based oils can be very sticky and provide a coating that stays put (ask anyone that burns WVO) but they also break down and grow mold in humid areas. Plus they have a unique smell. Lately I've been using a product called Fluid Film which is made from fat extracted from sheep wool. It seems to be very effective when applied full strength as I've found on some of our buses but it's a little tough to apply. This year I tried using a simple air suction gun and cutting the FF with turpentine. That approach uses much less FF, allowed me to easily blow the coating into boxed panels, and cleaned up with minimal effort. It seems to be effective and has the advantage of being environmentally friendly. I'll be able to report on effectiveness after this winter.

Oh, and one final note: Anyone in New England has heard someone say "salt rusts vehicles." While it's true we see much more rust where salt is used, the salt itself does not directly cause rust. Salt is hygroscopic and will attract moisture. Calcium chloride more than sodium chloride, but both will do this. When salt "dries" on the frame and body of a car, it never fully dries. Instead it continues to attract moisture from the air and will keep this moisture in contact with the steel frame and body causing rust.