Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Rust show stopper?

I’m on the market for a used car (my first car) and I recently came across a 2004 Mazda 3 hatchback with 40,000 miles, for sale by the owner, who bought it new in 2004. Since the owner was a student who lived near campus the milage is low. All mechanical functions are fine, and it has great extras like ABS and side airbags. The owner is trying to sell the car for $7k.

The car has spent its lifetime in Boston and Cleveland, two very snowy and salty cities. Besides a dented bumper and the only major body damage is a bit of rust setting in. There is a rust patch bubbling to the surface near the edge of the rear quarter panel about 6 inches long. Also when I took it to a mechanic to get the car checked out, I saw the rear crossmember is also starting to rust a bit. The local body shop says it could patch/sand/paint the rusting on the body but it will cost $800.

My questions are: (1) Is that enough rust to not buy this otherwise great car? (2) If the rust is left alone and the body is not patched, how long would it take for the frame to corrode? (3) Most importantly, once a car starts to rust, does it matter if I take care to clean out the car in the winter? Even if I get the rust on the body fixed, is it even going to make a difference to clean off the salt on the undercarriage in the winter? Thanks for your feedback.

I wouldn’t touch it. Once rust starts, it tends to spread quickly. That $800 repair job probably won’t last all that long.

I, too, would avoid this car.

That’s a considerable amount of rust, and there is no reason why an undamaged 6 year old car would rust that badly that fast in those locations. My car has been subjected to ludicrous amounts of salt for the past 7 years in Ohio and 6.5 years in Michigan before that. After all that, I’ve never had more than a dime-size spot of surface rust that was easy to touchup.

I’d suspect that the car was damaged at this rear quarter panel and then poorly repaired.

The Carfax was clean, but the owner said he never cleaned out the salt in the winter, which, I suspect, is why there is so much rust.

The carfax can be clean after an accident if no insurance claim was made. If the owner fixed it himself, or paid for it himself, it won’t show up.

Frankly, I have serious doubts a sto whether it’s likely to show even if an insurance claim is filed. There is no mandatory reporting database, and I’ll wager that many insurance companies don’t report to CarFax.

I personally have serious doubts about the credibility of CarFax data. It might be a public service for some consumer protection agency to investigate their data collection system and the accuracy and comprehensiveness of their data.

Rust on a car is sort of like an iceberg. The part that you can’t see is much larger than what you can see.
In other words, for every bit of rust that is visible, there is likely much more that you can’t see.

Since this car–like most nowadays–uses unitized construction, rusting of the undercarriage means that the structure of the car has already been compromised to at least some extent. In addition to reducing the effective lifespan of the car, this weakening of the car’s structural integrity can have some nasty consequences for driver and passengers in the event of a crash.

Fixing the visible rust on the body of this car will be like sweeping the dirt under the carpet. Visually, things will look fine, but in reality they are not.

Since there are many cars on the market without a significant rust problem, I strongly suggest that you take a pass on this one.

Well, I have never cleaned out the salt in the winter in either my 1997 Taurus or my 1998 Camry - and neither of these vehicles have ever shown more than the tiniest speck of rust.

I don’t believe this seller…

With the kind of rust you are describing, you cut that asking price in HALF…The rust blister on the rear quarter is forming from the INSIDE, you don’t want to see the back side of that panel…By repairing the damage NOW, using a rust converter/neutralizer, and a few spray-cans of Rust-Oleum underneath, you can greatly slow down the progression of the rust and get some decent service out of this car…But NOT for $7 grand…

I have to agree that rust is the big factor and mechanics are secondary. Rust can be unseen until something falls apart at 70mph or someone gets a little dizzy from the fumes. The only rusted vehicle I would consider is a PU truck with bed only rust in something I could swap out. I’d rather have a perfect body and mech. problems any day. I agree; look elsewhere.
BTW, if it’s in the rear quarter, access is through the trunk/rear side molding on the interior. The car sounds close to being “un-inspectable”.