RUST under my 2014 Mazda3 - fixes


Mazda Axela 4WD GT (Lexie)
Today, after washing and drying the car I had a surprise waiting for me.

Found a little rust spot under the car, where the body meets the chassis. Likely caused by a stone chip.
It had already started spreading a bit under the paint.

Here is how I repaired it.



Sorry, i forgot to take a picture before I started sanding.
So, as you can see, I removed the "dead" paint and sanded the area.

I then, sprayed brake cleaner all around that area just to remove any oils, wax or anything that could prevent the undercoat paint from sticking.

I got some undercoat spray - VERY thick black spray.
This one is written in japanese but I am sure you can get something similar where you are.


Then I sprayed a thin coat first, just to creat adhesion for the the second and third thicker layers.
The photo was taken after the third coat, while still wet.


I did this on the other side too - albeit without sanding as there were no stone chips or rust spots.

I will most definitely get mud flaps installed next time I take the car in for a service.

Hope it helps.

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Just did a further check.
And unfortunately, i found a bit more rust on the rear suspension arms.

This is bulls***, so I have decided to have the whole chassis painted and rust proofed.

The car has only got 12,000 kilometres. This is ridiculous, I am so sad

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The rust spot under the rocker is a surprise. I would mention that to the dealer, if you had not repaired the spot already.

Rust on the suspension arms does not surprise me since the paint on those parts is low grade. Short of a rock guard coating, rocks will chip any paint you put on those parts. The rock guard coating dries hard and milky clear and can be painted. There are other products with similar capabilities, possibly your repair product is one of those.
I freaked out a bit as it was spreading already.

Do you reckon it's worth it showing the rear suspension to the dealer?

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You can try but I believe that the dealer and Mazda will say that is normal. Unless the rust is something more than surface rust, I do not beleve the structural integrity is compromised.
You should see the engine bay and underside of our Protg. It spent a few years in New York. Fortunately, it runs great and shows no signs of structural weakness.
I dont mind a bit of surface rust. But what saddens me is the fact the car only has 12,000 Ks.
What will it look like in 3 years time?

Im not even going to take the car to the dealer. It's going to the paint shop on Friday to have the whole chassis and suspension arms rust proofed.
Now the question - will rust proofing void any warranty?

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Not speaking for Mazda, I do not see how rust proofing some suspension bits would affect the warranty. That said, ensure the shop does not block various drain holes in the car bottom. Blocking any drainage holes is an invitation to disaster. I realize you did not ask for my opinion but I do not believe this is a good idea.
I did ask for an opinion!!

Thank you!

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I think every car I've ever owned has quickly developed rust spots on the underbody components. I've never had a serious issue resulting from it, even after 6 years and over 200,000 miles on one of them. If you live where salt is heavily used in winter, it's going to happen, and quickly.

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