What to do if the bottom of the car is rotten

Methods for sealing the underbody of a car without welding

A source of through corrosion, or simply a hole, in the bottom of the car is the price to pay for comfort in the cabin. Its primary source is not anti-icing reagents acting outside, but moisture accumulating under the “pie” of heat, sound and waterproofing. Therefore, when eliminating it, work is carried out mainly from the inside.

If you follow all safety rules when welding, you must completely dismantle the interior, including the trim. This is always very time consuming. Therefore, the question of how to seal the bottom of a car without welding is very relevant. Moreover, most alternative methods do not give worse, but rather better results.

Cold methods of sealing holes in metal

There are two ways to repair holes in the underbody of a car without using hot work.

1. Using composite materials - various types of polymer resins in combination with a reinforcing filler and a curing reaction accelerator. With high-quality surface treatment, in addition to restoring mechanical strength, they play the role of inhibitors - retarders of chemical and electrochemical corrosion reactions;
2. Installing sheet material patches onto rivets.

General technological rules

Holes in the bottom are usually discovered from the outside, when inspecting the car on a pit or lift. Signs of through corrosion are local swellings, which, when you try to pick them out, crumble into dust.

If you find such troubles, you need to open and remove the pie of heat, noise and waterproofing on the floor in the cabin in the entire area where the sheet of iron forming the floor is welded to the power elements of the body - thresholds, tunnel and others. Then you will see the whole picture of the damage and will be able to take preventive measures in those places where corrosion has not yet become through.

Before the process of sealing the holes itself, you need to take measures to slow down the corrosion process (stopping it is an unattainable ideal to strive for). To do this, all iron rags are removed, and the edges that have residual strength are treated with sandpaper and a wire brush until shiny. The cleaned surface is treated with rust converters. For example, the “Tsinkar” composition. Work is being carried out inside and outside.

After completion of the work, the surface of the unprotected metal is covered with bitumen mastics, putty (acrylic, epoxy), paint or gun fat.

The work makes sense if the total surface of through holes does not exceed 15% of the floor area.

Fixing pinholes

If the source of through corrosion has a diameter of no more than 1 centimeter, it can simply be covered with a two-component polymer composition. Poxipol glue or a cold welding kit similar to plasticine gives good results.

A small hole makes it possible to use so-called cathodic electrochemical protection. Find an aluminum rod, make a rivet out of it and fill the hole with it. Within a radius of 20 cm from it, corrosion will stop. True, the rivet will gradually collapse on its own. But this may take five years.

Repairing large-scale damage

In this case, you will have to take care to restore mechanical strength. If the hole is on a flat area, then there is no point in messing around with epoxy and fiberglass.

A truly durable composite material is obtained only with absolutely precise adherence to technology - mixing proportions, drying mode and much more. Use ready-made material of this kind, for example, textolite. Having a thickness of 3 mm, it is not inferior in strength to sheet iron. The plate can only be installed with epoxy glue, but it is better to use a combined connection using rivets. The latter should be made of aluminum, then they will play the role of cathodic protection.

Long holes at the joints with power elements are eliminated with patches made of sheet iron or aluminum. They need to be bent according to the shape of the joint so that the width of the contact zone with the still living material is at least 2 cm. They are installed on aluminum rivets; the use of an epoxy compound would be useful. Especially if sheet metal is used. After all, you cannot know exactly its composition and in which direction electrochemical corrosion will go - whether it will destroy the patch or the body. The polymer resin will act as an inhibitor.

The final sealing of cracks and holes is carried out using, for example, the Novol Plus 710 kit. In addition to the epoxy filler and hardener, it includes a piece of fiberglass.

Is it worth soldering

You can also seal holes in the bottom using soldering. However, ordinary household soldering irons are not suitable for heating metal with a thickness of 0.5 mm or more. Most likely, a hair dryer will not help you with this. You need to use a portable gas burner, for example, Super-Ego R355, which fits into a small - volume from 400 to 700 ml - cylinder for camping stoves.

Solder and flux are required for soldering. The solder used is low-melting, with a predominant content of tin or lead. Flux can be replaced with electrolytic acid. The connection is strong and can withstand high vibration loads.

Soldering has two disadvantages.

1. It involves hot work, which increases the overall complexity of the repair. This can be neglected if your hands grow from the right place;
2. The main material of solder - lead or tin - is a substance that has a lower electronegative potential than iron. Therefore, upon their contact, electrochemical corrosion occurs, in which iron will play the role of a “sacrificial anode” and be destroyed.

Now you have an idea of ​​how to seal the underbody of a car without welding. If you are careful and persistent in cleaning the surfaces, then treating them and protecting them, then the installed patch can outlive the car itself.

Rotten bottom. Repair

Demonidze said: 03/04/2010 19:27

Rotten bottom. Repair

Angel735 said: 03/04/2010 19:42

rob104 said: 03/04/2010 19:45

amateur said: 03/04/2010 20:04

_RAZIEL_ said: 03/04/2010 20:27

with such thoughts, the new car should be sold immediately after the first maintenance, after all, the oil was changed, the spark plugs were changed, which means they have deteriorated, which means it is unsafe to operate the car further, and what if further.
The brake pads were worn out, I replaced them. It’s urgent to sell)))))))))) and cars after thorough repairs are generally prohibited from use; everything tends to wear out, wear out, and rot.

To the author of the topic, go to a tinsmith, let him take a look and decide on the scope of work. For example, I cooked my own P10 (I digested the entire rear and trunk) 3 years have passed since then and the car is still driving (I see it all the time in the city), although the current owner dented the front fender and broke the radiator grille. probably due to the fact that I cooked the body work in the back

ROW111 said: 03/05/2010 08:46

Demonidze said: 03/05/2010 10:23

amateur said: 03/05/2010 10:30

Demonidze ,
they told you - GARAGES. what car service?? a lot of extra money? Then you go straight to the dealer.

don’t know how to find Vasya? I'll explain. you slow down any domestic classic. The driver must have been over 40 years old. and you ask - you can’t tell me where it would be possible to do this and that.

Repair of a rotten body and its features

Repairing a rotten car body is a necessary measure that the car owner resorts to. The main problem of any machine is, of course, its metal frame, which is subject to corrosion. If faulty components and mechanisms of a car can be easily sorted out, repaired or replaced with your own hands, then you will have to tinker a lot with a worn-out body, especially if it is completely rotten in places.

Features of body wear

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Body repairs are also considered very expensive. Carrying it out in a garage, on your own, without the proper equipment, is several times more difficult than at a service station. They say, and this is rightly noted, that acquiring the skills of a body specialist for the sake of a single sample car is not rational, but this is exactly what the owner will have to do if he decides to take on the task of repairing a rotten body.

Body deformations are the first thing you should pay attention to when buying a used car.

So, the car body wears out according to different scenarios, but in general, only three options can be distinguished.

1. Wear and tear caused by natural causes.
2. Body defects caused by exposure to rye.
3. Dents and damage caused by road accidents.

The first type of wear is inevitable. No matter how carefully and carefully the owner looks after his car, over time the body still wears out. The shine of surfaces is lost, the ostentatious fine decorative features are no longer used, plastic and rubber elements become unusable, and the interior upholstery is worn out. Due to fatigue cracks that occur in the car frame, door straps sag, the functioning of locks and other mechanisms becomes worse, trunk lid torsion bars become weakened, etc.

While some of this can be restored relatively easily, others are restored with great difficulty.

It is interesting that, based on the indicator of natural obsolescence, it is easy to very accurately determine the age of the machine, its operating conditions and regularity of maintenance.

How to identify a weak or rotten body

Usually, a rotten body is easy to spot right away. In some cases, doing this with the naked eye can be extremely difficult. Below are some useful tips to help identify a weak body.

• When open, the car doors are lifted out of the frame. If there is a noticeable lift, this indicates severely worn hinges and poor condition of the body itself;
• Poorly functioning luggage bars can also indicate a worn-out body;
• Pay attention to the hood hinges. If they have a strong backlash, then the body is already worn out;
• In the cabin, the seats and plastic parts wear out the fastest.

Methods for repairing a rotten body and its components

Below are ways to restore the body and its elements with your own hands. An old car, like a woman, has many secrets that will have to be revealed during the repair process. The car may require repair of a rotten sill, apron, fender and many other parts, or it may itself be completely rotten. In the latter case, as a rule, it is easier to replace the body completely.

If the doors of a car are rotten, then this is most likely the work of corrosion. The latter occurs in the place of the door where there is a small gap where air does not enter. Rust starts from here, from the inside. At the beginning of the development of corrosion it is quite difficult to notice, but then it inevitably comes out.

Here's what needs to be done to restore the rotten areas of the door:

• Carefully cut out the rotten part;
• Make a patch of the desired shape from a metal sheet;
• Insert the patch through the triangular hole cut in the body;
• After this, you will need to scald the metal;
• Clean the welds using a grinder;
• Now is the time to apply the rough type of automotive filler. It is also called hairspar or glass spar;
• After the first layer of putty has hardened, it is sanded with 80-grit abrasive;
• After this, grinding is carried out with 120 grit.

Note. Grinding is carried out either manually or using a grinder. The first option is good because it gives excellent results and quality of work. The second option is a big time saver.

• The final layer of putty is applied, sanded off like the first layer in two approaches. First with sandpaper on 220, and then on 320;
• Afterwards a primer is applied;
• After drying, paint.

Among the features of restoration work on doors, one interesting thing can be highlighted. In most cases, doors rust not only in the lower corner area, but also along the entire part of the correct lining.

Severely rotten doors can also be repaired, but it is very expensive. For this reason, it is recommended to replace the door with a new one rather than spend money on exhaustive repairs. This is especially true for domestic cars, because the price of their body parts is relatively low.

Often the threshold on cars also rots. In general, replacing thresholds is considered a popular pastime for garage workers of all stripes. As a rule, repairing this part of the body begins with a thorough inspection of both sides. If you notice rusty spots or even spots, you should immediately begin restoration, otherwise the corrosion will go further.

In many cases, the threshold is hidden by moldings. It is impossible to determine the condition of the threshold until the molding is removed. Often, after removing it, the owner discovers a terrible picture - the threshold is practically not found, it is completely consumed by corrosion.

In addition, holes may appear on the underside of the car, as well as in the area where the connector is located. In these cases, the part has to be changed completely, including all three main elements.

The car threshold itself, as you know, consists of 3 main parts: the “exterior” (the panel on the outside), the amplifier and the connector. All these parts are connected by spot welding.

Corrosion on the threshold occurs more often for the most important reason - water gets into the threshold! The car manufacturer provides drainage holes - 2 or 3 along the edges and in the middle, but over time they become clogged with dirt. If you can clean them regularly, the thresholds will last longer.

On the other hand, if the drainage system is working properly, and the water is constantly drained, all the same, the internal cavities of the threshold become moistened, which also leads to corrosion over time.

Preventive measures to combat corrosion of thresholds include treatment with Movil. However, over time it thickens and becomes hard. It is clear that in this state it is not capable of protecting against corrosion.

In general, many experts do not recommend using Movil to protect thresholds. In their opinion, foreign-made preservatives with the ML index, whose purpose is hidden body cavities, have proven themselves better. If such a composition cannot be found, then processed oil is also recommended, which does not dry out compared to Movil.

So, before starting restoration work with a rotten threshold, you should dismantle both car doors and then remove the rusty thresholds.

It is recommended that before removing the doors, mark their location in the openings, which will make it possible to reduce reassembly time.

• Next, you should pull out the aluminum elements, some of the rubber inserts and raise the mats in the place where they will interfere with work;
• Remove old, rotten thresholds piece by piece. First, the part of the threshold that is located in the area of ​​the front door is removed, then - in the back, and at the end - the part in the middle;
• Welds are also removed by drilling with a thin tool;
• The remains of the connector are drilled out only after removing the bitumen shvi (the latter, as a rule, is applied to a number of car models of domestic manufacturers);
• The outer part of the threshold is removed in such a way that half a meter long sections remain on the side of the wings. They are then used to secure the new part;
• The threshold amplifier is also removed. It is also recommended not to touch some part of the connector, preferably from the front;
• It is advisable to leave a small part of the threshold amplifier under the central pillar. A fresh amplifier will be installed on the remaining overlapped area;
• After the threshold is removed, the metal is cleared of rust, and the rotten part of the body floor is cut out;
• The areas of upcoming welding are also cleaned;
• New threshold components are being prepared for installation.

Note. It is highly recommended to start fitting from the connector. It must be shortened so that at the rear it overlaps the subframe amplifier, and at the front it mates with what is left of the old connector.

• The connector is welded;
• The amplifier is shortened, and a cutout is made on it in the area of ​​the central pillar. The latter is done so that nothing interferes with the installation;
• The lower zones of the parts are leveled;
• The amplifier is welded to the connector through the apertures;

The weld points at the bottom of the connector are cleaned. This is done in order to ensure the correct fit of the body elements;

• We adjust the outer empty panel, and then butt weld it so that there are no gaps left;
• The panel is also welded to the amplifier;
• At the end of the operation, we weld a connector to the body floor;
• Two layers of soil are placed on the new threshold, and then it is painted.

Important helpful tips:

• At the bottom of the amplifier, it is advisable to drill fairleads several millimeters in size in advance. Leave their step around 5 cm;
• The soil on the connector must be removed in all places where welding is planned;
• It is recommended to fix the amplifier first with 2 clamps, and only then it is tacked by welding;
• All work is carried out on a machine that is parked on a level surface;
• Before finally welding the outer panel, it is recommended to hang the doors. This is done in order to be absolutely sure of the correct welding;
• At the end of the work, the threshold must be treated with anticorrosive.

If the body number is rotten

The body number plate also often rots on the car. In this case, if repair work is carried out (a patch is applied), then the officials of the authorities will appoint an examination in case of suspicion of deliberate liquidation or replacement.

As a rule, the car inspector, not finding the license plate, confiscates the car’s certificate and then issues permission to undergo an examination.

If it is proven that the lack of visibility of the license plate is due to corrosion and repairs, then the traffic inspector pastes a photo with the body number into the papers on the car, making the required marks. The audit as a process does not take more than a month.

In some cases, if there is not much rust, it is recommended to treat the number with a converter or lubricate it with grease.

Report on the restoration of a rotting body

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Report on the restoration of a rotting body

I want to talk about what corrosion of body metal can lead to and how to deal with it when it is too late to prevent it with chemicals and protective coatings.
In principle, any car is susceptible to corrosion, but for some reason, Japanese Toyotas rot noticeably slower than cars from other manufacturers. Mazda is no exception, and maybe even in the forefront with Nissan, whose bodies quickly begin to rust. There are many factors here, but the main one, in my opinion, is insufficient anti-corrosion treatment of the metal and a thin layer of technological paint and varnish. Saving on this (reducing production costs) and the concept of producing machines for a certain service life (usually calculated for five years) are the roots of the problem.

So, I own a Mazda Familia 1995 1.6L BHA6R body.
I have owned it since February 2009. In the Russian Federation for 8 years, I am the fourth owner.

In the spring, the cabin began to smell disgustingly of rotten earth and rotten potatoes. Cleaning, washing and drying the interior did not give any results. It was decided to dismantle the entire interior to find the source of the stench.

To do this, the seats were unscrewed and removed (the smell clearly did not come from them), and the carpet was removed. Underneath were sheets of soft felt insulation. The carpet and insulation were washed with washing powder and dried. The seats were aired outside for several days and roasted in the sun.

Well, the interior has been dismantled, but the smell remains.
The next step is to peel off the factory bitumen sheets glued to the sheet metal of the floor. This turned out to be easy to do, since the sheets had peeled off in many places due to age.

What we see: along the empty beam, the floor metal has rusted and turned to dust. One press with a screwdriver is enough to create a hole. Upon closer examination, the rusty rot turned out to be saturated with moisture, like a wet sponge. It was from her that this disgusting smell came.

Miniatures

Holes in the bottom. Is it possible to drive a “rotten” car?

If the body is rusted through, then repairs will cost a pretty penny. A rusty car will require welding and subsequent multi-stage painting. However, there are places on the body that cannot be repaired in principle. Rust on them is a death sentence.

What is more important in the body?

It is most dangerous when the built-in power elements, which form a spatial frame that gives rigidity to the body structure, rot. These elements turn the car's cabin into a durable capsule. The body holds the engine, transmission, suspension, and other technical components. There are crushable zones at the front that absorb the impact energy. Each element of the engine compartment, especially the side members, acts here as a tin cushion, designed to dampen the collision impulse due to its own destruction.

Therefore, it is so important to keep the power frame intact and prevent it from rusting.

When does a car start to rust?

Metal oxidation under the influence of water and oxygen is enhanced if catalysts for this process are present. Anti-icing chemicals, salt and dirt activate reactions and provoke the formation of oxides (rust).

Foreign cars coated with galvanization and a good anti-corrosive agent receive a guarantee against through corrosion for 7-12 years.

On many domestic models, problems occur after 3-5 years of operation. The most susceptible to corrosion are wheel arches and fenders, sills, underbody, the front edge of the hood and the base of the roof pillars, as well as suspension cups and front side members.

What kind of damage can you drive with?

On domestic cars produced in the 1990s, rust usually spread wide and deep. If there was a red dot on the outside of the body under the swollen paintwork, this meant that everything on the inside had already been eaten away by rust.

On foreign cars of the same years the situation is slightly different. Corrosion penetrated deep into the metal and left through holes locally, but rarely spread to the sides.

If the doors, sills, edges of the hood, or even part of the bottom in the trunk are “rotted,” then this is not so bad. These parts do not bear any load (like the wheel arches and fenders), so you can drive.

You can drive for a decade with brown wormholes on the wheels and not experience any particular difficulties even with passing a technical inspection. They are not included in the list of serious faults. If the rust on the doors turns out to be too noticeable, the craftsmen will offer to perform cosmetic body repairs. The sheet of metal is cleaned, and then a layer of putty is applied to it, followed by painting. You can drive this car relatively freely.

Needs serious renovation

But most often the wheel arches and the bottom are destroyed. This happens unnoticed, since it is difficult to look into it. If the car is not serviced for a long time, then at one point a trip to a contactless car wash turns into an unpleasant surprise. The Karcher jet pierces rusty metal right through.

Even garage technicians can repair the identified pockets of corrosion. The metal is protected, the problem area is cut out by gas welding and repaired with new sheets of metal, after which the body drives for about another 3-5 years until rust makes itself felt again.

When is it no longer possible to drive?

It is much worse when the bases of the roof pillars or the power structure of the sills, the cups of the struts or the side members in the engine compartment have completely rusted. All these places belong to the load-bearing elements of the body. If the rust has penetrated a third of the thickness of the metal, then driving such a car is already dangerous.

It's easy to spot serious problems. When driving over artificial bumps, the body flexes excessively under load. If you climb one wheel onto a stone or curb and stop, then the “rotten” body may have problems opening the doors or trunk. The body bends, deforms and pinches moving elements. There is nothing good about this anymore. In the event of an accident, such a body will not be able to resist the impact impulse and will collapse like a house of cards.

Metal cups also sometimes rust through. Their damage is indicated by knocking in the suspension and noticeable problems with handling.

It is no longer possible to drive with such damage due to the risk of a serious accident. It is impossible to fix them, although some garage mechanics, of course, weld patches onto the side members or try to restore lost suspension fastenings, but it is no longer possible to restore the body’s former strength.