Rust: it did for the Lancia Beta and it has consigned many a motor to an early grave.
Today, car makers claim they’ve got it under control with better pre-production treatments, more use of aluminium, plastics and composites, and smarter design but, even so, it appears it hasn’t quite been banished.
In 2013, of the 27,285,855 Class 4 vehicles (cars and light vehicles up to 3000kg) that had an MOT test, 1,393,721, or 5.11%, failed on corrosionrelated issues either of components, component mountings or the vehicle structure itself. With numbers like these, it’s no surprise people have a view about rust. For this story, I posted my own experience of owning a rusty Vauxhall Zafira on the Pistonheads forum. It triggered a wave of rustrelated anecdotes and observations (see below).
Recently in Autocar, James Ruppert shared the story of reader Nick Williams and his 2008-registered Honda Accord 2.4 auto, which had a rusting sunroof. Thankfully, Honda replaced the car’s sunroof without quibble.
However, just as rust has a habit of spreading, so did Ruppert’s assertion, in his report, that despite car makers making huge strides in fighting tin worm, it has never entirely gone away. Evidence supporting his claim arrived at the Autocar offices almost immediately. Michael Ward, a Bradford-based independent motor engineer who spends his days doing pre-purchase vehicle examinations for customers or for people in disputes with sellers, provided the most compelling.
“Rust can be found in various makes and can be serious,” he wrote. “I find it hidden behind plastic wing liners, sill covers and undertrays.”
Ward backed up his claim with photographs of a 2004 Vauxhall Zafira he’d just inspected whose subframe, adjacent to the car’s wishbone mountings, was badly corroded. “There was no clue to its condition until the undertray, which is often not disturbed during servicing, was removed,” he said. “The undertray has a felt-type soundproofing material which had held moisture and which, I suspect, was the cause of the corrosion. I suspect there are many others like it.”
I asked Vauxhall why it continues to install rust-promoting undertrays on its cars. A Vauxhall spokesman defended their use and said, to be on the safe side, the company carries out annual inspections to check for rust: “It is general industry practice to install these type of undertrays to improve airflow under the vehicle and absorb engine noise. The company has a six-year antiperforation warranty [corrosion], which requires a customer to present their vehicle each year for an inspection to maintain it.”
I then contacted Ward, partly to hear more about his rusty Zafira but, really, to establish his credibility. He seemed a plausible witness.
“I’ve been inspecting cars since 1986; typically five a week,” he told me. “I rarely see incidences of serious corrosion but it still happens. Sometimes, body cladding moves and rubs the paint. Often it forms behind sill covers, wheel arch liners, under body panels and engine undertrays where metal surfaces can’t dry. MOT testers won’t take covers off to check behind them, so corrosion may be happening out of sight.”
Motor engineer James Carswell of Scotia Vehicle Inspections, based in Greenock, claims to have seen plenty of rusty cars in 56 years of poking around the things. One of his standout memories, however, is not of corroded Crestas or rusty Rovers from way back, but flaky Focuses from just four years ago and, more recently, dodgy Dacia Dusters.
“Around four years ago, Ford commissioned about 20 vehicle inspectors, including me, to check certain Focus estates for tailgate rust,” he says. “During the 18 months I was employed by Ford, I checked 10 to 15 cars a day for two weeks every month. Approximately 10% of the cars I checked had signs of rust. Ford was very good about it and did a thorough repair, or replaced the tailgate.”
A Ford spokesman confirmed Carswell’s story: “We ‘recalled’ Focuses with rust perforation under their 12-year warranty. It was at the tailgate. Something inside the panel was rubbing the body down to the bare metal. It was about three to four years ago and the cars were coming towards the end of their warranty, so they’re old now.”
More recently, in the past year, Carswell claims to have inspected four Dacia Dusters rusting at their seams, and behind the sills and headlights.
A Dacia spokesman told Autocar: “On a limited number of right-hand-drive Dusters, built in India for the initial production phase and delivered between January 2013 and August 2014, it was found that an inconsistency in the process of painting the bodywork may have caused some surface corrosion on certain panel edges. A robust repair was arranged for any Duster that may have needed it. Right-hand-drive Dusters from Romania are not affected.”
Dr Martin Strangwood, senior lecturer at the School of Metallurgy and Materials, University of Birmingham, says applying a good anti-corrosion coating to a car is vital for a long, rust-free life. He says: “It’s crucial the correct layer of anti-corrosion coating is applied. Occasionally, its protection is used up too soon; perhaps where the metal component is concealed behind a plastic cover and is permanently damp. Also, it’s still difficult to put a thick layer of coating on complex shapes.”
However, for all the car industry’s huge strides in anti-corrosion protection, Strangwood says there’s still one chink in its armour. “Galvanised steel offers only sacrificial protection. The zinc element of it will corrode in preference to the steel. That’s fine because the zinc is not structural – the steel is. However, it does mean the coating has a finite lifetime. To extend it, in winter, people should wash the road salt off their cars.”
Whether your car is rusty or not, that’s probably one thing we can all agree on.
What you said about rust
We posted a tale of a rusty used car on Pistonheads recently. Here are just a few of the responses that it attracted.
“Mk2 Focuses suffer a fair bit with tin worm, and my 58-plate Mk2.5 is starting to show signs of it.”
“Recently, I’ve seen more than one Mazda 6 with rotted sills and arches, as in large MOT failing holes.”
“Anything Japanese will still be prone to a bit of rust. It’s because they don’t use salt on the roads, so don’t need rust protection.”
“A lot of modern rust issues are specific failures — arch liners rubbing through paint, and blocked drainage channels.”
THEY DON’T RUST
“French makes are pretty good for not rusting.”
“I’d say, on balance, things are leagues ahead of where they once were.”
The metallurgist’s view
Dr Martin Strangwood — senior lecturer at the School of Metallurgy and Materials, University of Birmingham — on anti-corrosion protection.
“A lot of today’s high-grade steels are pre-galvanised to provide anti-corrosion protection, and their edges coated and protected after cutting. Bodies that are made from steels that have not been pre-galvanised will be hot-dipped to galvanise them thoroughly. A polymer coating might then be applied before painting. This trend towards more complete protection dates from the Lancia Beta, which was only partially protected from rust.
“In general, the level of corrosion protection will be influenced by how much coating is applied, and how well. Today, coatings and the metals they’re applied to are developed together, so you can coat the metal thoroughly and evenly before it has been formed.
“There are geographical differences in levels of corrosion protection. Vehicles supplied to the Gulf states don’t need to have such a high corrosion resistance. Those supplied to the UK need greater protection from road salt. In Russia, much of the soil is acidic because of the pine forests. If you’re supplying a global market, you need to plan for all these eventualities and over-specify your corrosion resistance.”