Rust protection

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Introduction

If you want to invest in your vehicle's longevity, you need to pay attention to rust. In some markets and versions the Jimny is galvanised for additional protection.

If there is rust, it should be remedied before it gets worse. If there is no rust, it should be remedied while it still has not appeared.

So, scrape and clean the rust from the underbody of the vehicle (if it has rust), and then protect the underbody against future rusting with some good anti-rust material.

General idea

Areas of Jimny which are most susceptible to rust:

1. Boot / trunk floor
2. Below the rear seats
3. Inner wheel arches
4. Bodywork behind the side plastic mouldings (claddings)
5. Bodywork behind front driving lights

There are several schools of thought regarding which materials and methods should be used to achieve anti-rust protection.

Some use coatings ("underseals") like bitumen. However, these coatings can hide the rust behind them if the surfaces are not thoroughly cleaned prior to coating application, or if the coating has not been thoroughly applied, so the moisture "creeps" under.

One alternative method is to apply "rust inhibitors". Most of them work on the principle of chemically altering the rust itself, "freezing" it or chemically converting it into another substance. They are usually quite expensive, and typically do not have an effect on non-rusted surfaces (rust must first appear, and then you apply the inhibitor).

There are other alternative methods and substances. Explore on your own.

One of many manufacturers of products which deal with rust is Buzzweld (suggestion from a forum user).

Some quick guidelines

Below is just a quick write-up which needs proper "sortiment" (division into subchapters, better explanations etc.)

In general, the best results by far can be achieved if the vehicle is first dismantled (body separated from frame). However, that is a major undertaking by itself and can be quite unpredictable process with older vehicles (many stuck bolts which break off, some flaky brake lines which crack during removal, some stuck bolts in the bushings will require replacing the bushings, etc.).

If the body is separated from the frame (and the transmission and the suspension, which remain on the frame), than the underside of the body can be thoroughly cleaned and protected, as well as the top of the frame/chassis.

However, the dismantling can be taken further to the "complete" level by also dismantling all the transmission and suspension elements from the chassis. Then the bare chassis can be dipped into a hot zinc bath ("hot zinc plating" process) and this is the only method which cleans and protects the inside of the chassis tubes and rails. There is no other solution for the complete chassis protection. Cold zinc plating (also galled zinc galvanization) is thinner and can be applied only to the exterior surfaces of the chassis, not to the interiors. Note that the process of both hod and cold zinc plating usually implies prior dipping of the material to be treated into a pool of special acid, which kills of any remaining rust, dirt, greases and bad spirits. This is usually included in the price of zinc plating.

Of course, each dismantled suspension and transmission piece can also be taken for zinc plating or some other coating (but the bushes have to be removed first in some cases).

After a vehicle component iz zinc plated, it can then be treated with a "final" coating. There are several materials which can be used - automotive wax, bitumen-alike coating, plastic-alike coating (not recommended outdoor applications), or hard bed-liner coating. Whichever final coating is applied, the application should be done in at least two passes (2 layers).

Opinions on which final coating material is the best vary as much as do opinions on an only proper world religion.

(Allegedly poorer) alternatives to hot or cold zinc plating are to paint the bare metal with a good quality primer paint (preferably 2-component one) and then apply one of the mentioned final coatings.

However, the most important part of this process is the prior removal of the existing rust. Rust is like cancer. If even a tiny untreated bit remains, it will spread again all around in due time. A standard method of rust removal is by using manual or powered wire brushes (attached to drills, grinders, etc.). However a much more thorough rust removal can be accomplished only with sand blasting.

Sand blasting is of course done much easier and with far better reach is the body is dismantled from the chassis.

Whichever rust removal procedure is performed, (if the surface will not be dipped into a zinc bath), the treated surfaces should then be "painted" over or sprayed over with some rust treatment (elimination) chemical. Its job is to kill the last tiny thin remains of rust which might have stayed in some pores or scratches after the mechanical removal has been performed. The best chemicals for this job are the ones which chemically alter (transform) the rust into another non-ferrous material (making it impotent). These chemicals are much more expensive than ordinary "rust melting / elimination" chemicals. Prices are usually about 20-40 EUR per liter, but they are well worth it. An example manufacturer of these chemicals is Wurth from Germany.

A rust treatment chemical usually needs about 12-24 hours to do its job. Some of these chemicals require grinding them off after they harden off, while others allow further coating applications like it's a bare metal.

Note that timing and weather protection is important during the entire process.

For example, if you sand blast the chassis, and then load it onto a trailer to be taken somewhere else for the next phase, if it's a cloudy day with high humidity (let alone rainy day!), the metal will quickly develop rust flecks on the way to the next station. Or if you wait too long after the application of the rust treatment chemical, the chemical will "evaporate" and the rust will return from the air moisture again ....

Without vehicle dismantling:

If you do not go on the path of dismantling the body from the chassis (you most likely won't do that), then it is highly recommended to at least remove the fuel tank and possibly the transfer case as well before the rust proofing. Removing these two should not be difficult. It is just a bit fiddly to properly connect the fuel lines when returning the fuel tank back into position.

Removal of these two will enable much, much better access to the underside of the body below the rear seats and below the boot. These are the areas which usually suffer the most from rust on Jimnys, and these areas can be properly cleaned and protected only if the fuel tank (and preferably the transfer case too) are removed.

If the body is not dismantled from the chassis, then both of the zinc platings are not an option. Everything else what was mentioned above is still valid and possible (rust grinding, sand blasting, rust chemical application, primer paints, final coatings, etc.). It will just be harder (more effort) to properly treat all the surfaces and hidden "bays". Also be careful not to damage the brake lines and hoses, the vacuum hoses and various wires while doing th jobs ...

Note: Pressurized zinc spray cans are (allegedly) much inferior solution to proper zinc plating and they should (allegedly) not be used. Better to use a proper primer paint on bare metal.

Note: Most primer paints are porous, meaning that moisture passes through them. This means that you need to apply final coating(s) of your choice (which need to be airtight) as soon as the primer paint dries off. A lot of people leave the project for a while (maybe to take a rest) after the application of a primer paint, thinking that they have covered the bare metal and how the main "rust shield" is on, but it isn't! Primer paints provide no protection against moisture, they are just a "stop-gap" layer so that the final airtight coating can adhere properly!

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Page last edited on 24/05/2018 by user Bosanek