Recently I had a discussion with someone with a 2009 Mazda6 where the right front lower suspension arm separated from the engine support frame due to rust corrosion which caused the frame to break. Luckily the car was being driven at lower speeds and did not have an accident. He said that NHTSA had opened an investigation into a number of reported failures. I Googled the following recent articles about this issue:
Mazda MAZDA6 Frame Rust Problems
In his call to the Mazda dealer he learned that frames are on backorder, and that parts and labor could be $3000 for the repair. I have not heard what he has decided to do. He also mentioned that a contributor to this rust in this location is the air conditioner (A/C) drain directly above, where condensation can drain down and collect on the frame.
Because my son is now driving our 2009 Mazda with 155k miles on it, I had him bring the car home this weekend so I could do a thorough inspection in my garage. The car is in Michigan. As soon as I jacked up the car I could notice how wet the area was from the A/C condensation. He had this on because temps here have been in the 80s. Removing the front wheel/tire, I started scrapping around trying to detach clumps of surface rust before using a wire brush on the surface. My scraper broke through an area of the frame which had been covered by part of the plastic fender liner that is retain there by a plastic clip. I used some metal shears to trim away more rusted metal and a round file to further enlarge, at least until the metal seemed less fragile. The interior of the frame visible from that hole was full of wet rusted debris which I was able to vacuum out. I figured the least I could do was paint the frame area from just ahead of the suspension attachment all the way back to where the frame mounts to the body. I also removed, wire brushed and painted the frame attaching bracket that was easy to remove. I used Rustoleum rusty metal primer and then an overcoat of flat black paint.
There's no saying how weakened the frame is at this point as it is impossible to inspect the interior of the frame or areas hard to reach without removing the frame. As Neil Young sang, Rust Never Sleeps. However, in the hopes this will live for sometime longer, I needed to address the water coming from the A/C and try to redirect this away from that area.
I looked for the A/C drain outlet to determine if I could add a drain hose easily. Reaching up from the wheel well to the firewall, there is actually a short outlet tube/nipple that I was able to slip a length of vinyl tubing and add a small spring type hose clamp. The tube I used measures about 14mm/9/16" inside diameter. 1/2" would probably work as well. I also brushed on some Gorilla super glue when installing. I had trouble deciding how to route the tube as it passes near the V6 rear cylinder bank exhaust catalyst and I did not want this to touch or melt. I decided to bend the tube in a nice radius without kinking and lead this over and in front of the steering arm and then back under and over the sway bar, to end behind the engine frame bracket. I zip tied this to the bracket and to another insulated hose. Not sure what this was. I may try to add some insulation to the tube later if I see any indication of heat discoloration. I'll be checking this again in a couple of weeks. Alternately, someone might try a short length of tube extending from the nipple and then a 90 fitting with addition tube extending straight down past the frame.
Anyone concerned should have their vehicle inspected by their dealer or mechanic. I'm not sure if this is strictly an issue for cars from northern states/provinces, as the A/C condensation will be present in warmer states as well. Anyone that learns anything further from their dealer or receives any recall notification should try to post it here.