How to save your Mazda MX-5 Miata from rust

Mazda MX-5s are fantastic sports cars that prove great fun, easy to maintain, and generally bulletproof. However, rust can be a big problem - so here's how to save yours

The Mazda MX-5 is a joyous little car, packed full of charm and possessing one of the most playful chassis out there. Better yet, they’re something of a bargain with most generations still remaining affordable — although values of MK1 cars are rising fast. However, this little sports car has an Achilles heel, particularly MK1 and MK2 models. Rust!

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Sadly, for all of the MX-5’s ability to put a grin on your face, it can just as easily bring a tear to your eye, thanks to its issues with the dreaded red rot. This is something I experienced myself, as an MOT inspector took a small hammer to my car and and easily caved in the sills on both sides

Thanks to the known rusting locations being not a million miles from seatbelt mounting points, considerably costly work is often needed to make them road legal once again — hence all of the scare stories. However, there are a few easy things you can do to help preserve your pride and joy.

Eunos Roadster

To buy an import or not to buy an import, that is the question. Mk1 cars were sold as the Eunos Roadster in Japan and you’ll find that plenty of them have been imported. The big bonus of the Eunos is that Japan doesn’t salt its roads during winter, meaning that their chassis have spent less time in a corrosive environment.

Do bear in mind that this does not make them rust-free, especially as many have been living in their new nation for decades already.

Garage During Winter

This might seem like an obvious one, but keeping your car out of the elements will help. MX-5s have always been cheap and cheerful motoring, but today MK1s are appreciating assets that might just deserve some garage space. Follow all of the usual winter storage tips and count down the days until the sun comes out again.

Drainage

This is it, the big secret to prevent your MX-5 from the most costly repair of its life. Most MX-5s, certainly the Mk1 and Mk2 cars, have a gutter that runs around the back of the convertible top - just where the roof tucks into the back of the car. Water is then channelled down through the car and exits via a pipe just ahead of the rear wheels on each side.

The problems begin when the upper gutter or the exit pipes become blocked with dirt or leaf litter. If that happens, water can get trapped between the two points and rust the car from the inside out.

Thankfully, the solution is quite simple. Periodically clear the gutter of anything that may have collected in there to prevent blockage further down the line. Clearing those two exit pipes underneath is a little trickier, but here’s a technique that works.

With the roof up feel around inside the car where the roof meets the interior — to the side of the flat shelf. Locate a small tube protruding and slide something like a steel cable (or something else that’s lengthy that wont brake) down it. Slowly feed it through until it appears out of the drainage pipe under the car, usually accompanied by some gunk that was blocking it.

What’s that noise?

Hear water sloshing around when your MX-5 is in motion? That’s likely because there’s water trapped inside the cars sills, which can be bad news if left unattended. The easiest way to deal with this is a small rubber bung located just behind the front wheel, below where the indicator is. This little round rubber bung can release that water by gently pushing it inwards with a small blunt object. Be gentle and let the water drain completely before letting it fall back into place.

I learned all of this the hard way and ended up spending a considerable sum to get my Mk1 MX-5 back on the road. Follow these steps and you’ll have many happy years of motoring ahead.

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