[Swappy]

Hey guys, while looking at my car from the bottom front end, I found a little surface rust on this part , both sides, driver and passenger.

Can anyone please confirm if they have it as well or if it is normal ? My car is never winter driven and has only 26k on it. Just a little worried.

[Pauloxxi]

BMW does cost savings, and do not pay for coating protection or pain in the CVJ bell, so it rusts with time... they in fact don't expect people to keep looking for rust in hidden spots

[Swappy]

Originally Posted by Pauloxxi

BMW does cost savings, and do not pay for coating protection or pain in the CVJ bell, so it rusts with time... they in fact don't expect people to keep looking for rust in hidden spots

Oh so it’s normal. That’s so shitty lol. At least it’s a relief that’s it’s normal sigh.

[eugene89us]

Originally Posted by Swappy

Oh so it’s normal. That’s so shitty lol. At least it’s a relief that’s it’s normal sigh.

Ha, funny you ask. There are many spots on a car where cast iron immediately develops surface rust. The good news is that iron oxide provides a protective layer for the rest of the metal. I have some spots around untreated edges of differential, etc. Just for fun, here is a photo of an exhaust manifold on N47 diesel engine when car had between 10 and 20 miles on the odometer (brand spanking new, straight off the lot!) I freaked out, then accepted it. Now 50K miles later, still runs like a dream.

[Swappy]

Originally Posted by eugene89us

Ha, funny you ask. There are many spots on a car where cast iron immediately develops surface rust. The good news is that iron oxide provides a protective layer for the rest of the metal. I have some spots around untreated edges of differential, etc. Just for fun, here is a photo of an exhaust manifold on N47 diesel engine when car had between 10 and 20 miles on the odometer (brand spanking new, straight off the lot!) I freaked out, then accepted it. Now 50K miles later, still runs like a dream.

Wow, thanks for sharing. I was so worried when I first saw that. The more you know !

[328iX]

I live in California where nothing rusts but there are exceptions such as the axle (the part you pictured) and the rotor hub area due to water accumulation under the center cap.

My turbo and exhaust manifold are not rusted. The turbo appears to have a zinc coating? And my exhaust manifold appears to be stainless steel? It has this really cool finish on it from the heat.

[BWbimmer]

Aluminium spray, works on the brake disks as well.

[Skyhigh]

Yep... mine looked the same very very quickly. I was also a bit surprised...

[eugene89us]

Originally Posted by 328iX

I live in California where nothing rusts but there are exceptions such as the axle (the part you pictured) and the rotor hub area due to water accumulation under the center cap.

My turbo and exhaust manifold are not rusted. The turbo appears to have a zinc coating? And my exhaust manifold appears to be stainless steel? It has this really cool finish on it from the heat.

I had some rusting on rotor hubs too. I posted a thread somewhere on this forum where I described how to grease them to reduce rusting. X5 models are actually pre greased from the factory - I saw it when I was rotating tires. Our 3 series are not, so I used some copper grease and that so far stayed in place for about 10K miles. May be a good measure to take.

The exhaust manifold on diesels is cast iron, I guess due to DPF regens that can bring exhaust components north of 600 degrees C. Over last 50K miles, the cast iron darkened a bit from high temps.

[Billfitz]

Cast iron rusts. If your calipers and hubs haven't rusted yet sooner or later they will. It doesn't bother them, but it doesn't look good either. I paint mine with caliper paint, touching it up yearly when I have the wheels off to rotate the tires.

[328iX]

Originally Posted by Billfitz

Cast iron rusts. If your calipers and hubs haven't rusted yet sooner or later they will. It doesn't bother them, but it doesn't look good either. I paint mine with caliper paint, touching it up yearly when I have the wheels off to rotate the tires.

My original 5 year old calipers have zero rust. Not even surface rust. Same with every car I ever owned, never seen my calipers rust.

[dmanb2b]

Originally Posted by 328iX

My original 5 year old calipers have zero rust. Not even surface rust. Same with every car I ever owned, never seen my calipers rust.

You are also in dry and sunny CA, not the Northeast

[328iX]

Originally Posted by dmanb2b

You are also in dry and sunny CA, not the Northeast

I was responding to Billfitz saying my calipers will rust.. I'm aware where I live lol

[eugene89us]

Originally Posted by 328iX

I was responding to Billfitz saying my calipers will rust.. I'm aware where I live lol

I am in relatively mild Mississippi. We get maybe a day of snow if we are that unlucky per year. We have no road salt, no winter equipment really. We do get a lot of rain here. My calipers show zero signs of rust likely due to lack of corrosive salt use. However, the hub centers behind the BMW cover do have surface rust since they were not coated from factory. And some cast iron surfaces that were not coated or treated in some ways. I always wonder if my car has some rust, I cannot imagine how bad cars are for people living in climates with snow and ice.

One thing, my wife's X5, made in the US, also has cast iron manifold since it is also a diesel and had zero rust from factory on it. Mine was made in Germany, so I am considering that the time in the ocean that car spent was likely the time it was exposed to salt in the air, which cause surface rusting to appear, whereas US built cars do not have the same signs. But that is just a hypothesis. I will attach her cast iron manifold to here. So maybe California rust actually happened in the open ocean during transit?

[328iX]

Originally Posted by eugene89us

I am in relatively mild Mississippi. We get maybe a day of snow if we are that unlucky per year. We have no road salt, no winter equipment really. We do get a lot of rain here. My calipers show zero signs of rust likely due to lack of corrosive salt use. However, the hub centers behind the BMW cover do have surface rust since they were not coated from factory. And some cast iron surfaces that were not coated or treated in some ways. I always wonder if my car has some rust, I cannot imagine how bad cars are for people living in climates with snow and ice.

One thing, my wife's X5, made in TN, also has cast iron manifold since it is also a diesel and had zero rust from factory on it. Mine was made in Germany, so I am considering that the time in the ocean that car spent was likely the time it was exposed to salt in the air, which cause surface rusting to appear, whereas US built cars do not have the same signs. But that is just a hypothesis. I will attach her cast iron manifold to here. So maybe California rust actually happened in the open ocean during transit?

Yeah it's a definite possibility. I actually had my front axles replaced so it's no longer there and the material on them doesn't look like it would rust like the originals? But maybe because they're still new.

[undertaker]

Cold, dank weather in the North accelerates rust. Warmer weather decelerates. When I moved from Connecticut to Texas, years back, the tech never saw so much rust on the undercarriage.