As I’m looking, I’m finding a lot of used cars (particularly those under the GMC umbrella) with severely rusted out rocker panels. I’ve attached a picture of an example.
Mechanically these cars are sound and otherwise in great shape; this just seems to be a flaw in nearly all of them.
Is this a major concern?
If I end up with one of these I plan on having a friend just wheel all the rust and loose material off, maybe spray it with some type of sealant.
Wow, where do you live? I live in the salt/rust belt of northwest New Jersey and I see very little of this on cars. Pickup trucks are another matter. That includes Ford , Chevy and Dodge. Asian pickups are even worse. It’s beyond wheeling it off and sealing it.
I can imagine the damage underneath.
The only way to repair that kind of rust is to cut out the rusted metal and weld in new metal.
Anything other than that is a waste of time and money.
Tester
“I plan on having a friend just wheel all the rust and loose material off, maybe spray it with some type of sealant.”
Unfortunately, that would be merely cosmetic in nature.
More or less like sweeping the dust underneath the carpet.
For every bit of rust that you can see on the rocker panels, there is at least 3 times more rust in structural areas that are not readily visible.
I would strongly suggest avoiding vehicles with this much visible rust damage, and I also suggest having the good-looking vehicles put up on a lift for a pre-purchase inspection.
Yeah, rusted out rocker panels are definitely a serious concern. Generally it means the only thing holding the car together with any strength is the roof! Guess what’ll happen should you get in an accident? The car will scrunch up with you in the middle! And, since other things like the strut towers are probably also rotted out, you just might get in that accident!
The problem is exacerbated by the fact that there are still estimated to be many thousands of cars out there that were flooded in Hurricane Sandy and other natural disasters that have hidden rot. You need to be really careful on the used car market. There’s an occasional good find, but there’s an awful lot of cars out there with hidden serious safety problems.
I’m near Detroit: road salt capital of the world.
@the same mountainbike
Is it structural on the GM W platforms?
It seems to just be thin sheet metal. There is a more solid part of the frame above and behind the rusted outer portion.
Yeah, it’s structural, if you look at a newly made raw body I’ll bet that rocker panel is there as a part of the structure, and I’ll bet lunch that should you pull that rocker panel you’ll find other holes big enough to transport hero sandwiches in.
The only difference between these “slip on” covers and a bandage over a broken nose is that the nose will heal itself under the bandage… the rocker panel won’t.
The rust you see may be just the tip of the iceberg. If you do decide to go with it be sure to do a careful examination underneath, particularly the engine subframe.
Stay away from rusty W bodies. There have been reports of strut towers breaking loose. Here is a picture of the rear strut mount in the trunk of a 1998 Grand Prix.
That rocker panel would work. It’s made of steel.
But like I said, the rusted rocker panel would have to be cut out, and that new rocker panel welded in.
Tester
The one in the posted ad was, according to the ad, a “slip on”, strictly cosmetic. That’s not going to be the same as a replacement rocker panel welded in during a proper restoration. It’s probably 16 ga.
Without a doubt, these cars with rusted rockers are no longer safe transportation. Rocker panels are significant supporting structures in unibody construction. Funny. All you have to do is pop off the threshold trim found on nearly all cars and squirt biodegradable motor oil into cavity along the the length on the interior through the trim holes…it won’t rust. 9 times out of ten, the rust started from the inside.
Gah, 8 out of 10 of these cars are rusted out only on the rockers.
I’m from near Buffalo NY, since we get more snow and all our major highways have a “bare roads” po;icy , I think we use more salt per mile than you do.
A rust bucket like your pic is suitable only to get you through the winter.
I wonder how much stock in salt companies GM holds… 
The only cure is to step outside of the vehicle and let a salesman wheel up a different car where your standing.
Though we would like to lay all the blame at the feet of the auto makers and they could do much more, even if the steel were better, the general consensus is that the weld areas are the most susceptible to rust. Joining metal with epoxy or fasteners would go along way but then, what about crash tests. That’s why when you look for areas where rust starts first, look to the welds. In the rocker panels, as in the bottom of the doors, the welds on most cars are at the bottom. That’s where most of the welds are, that’s where much of the water and salt congregates from the inside. Displace the waiter in these areas and rust can be delayed for many years and is relegated to starting on the outside where you can see, neutralize, sand and paint it. Bottom line, cars are really not made to last in the worse areas of the US more then six years, the length of most perforation warrantees.
Many years ago, the first time I removed a fender to paint on my car that was just four years old (damage) and showed no external rust what so ever, I was amazed how much rust had started on the interior. I was convinced then that we can’t sit around and wait for rust to bubble through before we do something. It was then I started listening to a good friend at work who kept cars over twenty years old that he still used for winter driving and had no rust what so ever.