Rusted bolts under car

[Jdcole82]

I bought my first BMW last week. It’s an 07 328xi coupe. It was originally in New Jersey and was only driven about 5k per year there so I think it was mostly a summer car. However it looks like it did get some salt exposure on the undercarriage. All the paint and structural parts look rust free, but there is some rust on many of the bolts. My mechanic said if he ever needs to remove a bolt to work on something it could break. He recommended I spray some PB Blaster on all the rusted bolts to remove some of the rust and slow down it’s growth.

Is this a good idea? Will it loosen the bolts too much?

I want to keep the rust from spreading beyond the bolts, especially to the frame. I don’t really understand how rust works. Does it just gradually spread everywhere?

I’d like to keep this car many years, but these rusted bolts have me worried.

[MarcoZandrini]

The best penetrating fluid is a mix of automatic transmission fluid and acetone. Google for the mixture. However, spraying any penetrating fluid on a bolt or nut won’t loosen it. And it won’t pritect the bolt from corrosion.

[Jdcole82]

Is this just surface rust?

[Stefan666]

Nothing to worry about, any "sea parked" car got that, usually way worse depending how long they live down there.

In truth.. i would not think about it anymore,
IF you want/need to remove them, spray it with some IMAL ( soak it, if possible.. even -days- up front )..
Removing corroded nuts/bolts ain't that hard with the correct tools / if your used to it.

For the plating under i would just clean it up, and spray it with body shuts ( translation ? ) its some kind of black tar
that lays a protective coat..
Do remove / brush away the rust first.

If its a eye sore, you could clean up the nuts/bolts and spray em with a protector.. but.. in truth..
Unless you roll it, ain't going to be seen

[Jdcole82]

Thanks, Stefan.

Even though it’s just cosmetic now, overtime will it turn into a structural/safety issue?

I’d like to keep this car many years so I was considering a body shop to thoroughly get it all off, but if it’s just cosmetic and won’t get worse, I’d like to save the money for other maintenance issues.

[Stefan666]

Of course, only to judge "under the car" .. but , when i look at the pictures.. i dont see a structural or safety issue now, or to come.
( keep in mind, i live near the sea ) , our cars get harsh conditions..
"this is nothing what you got down there" , and they all drive perfectly , and are easy to repair.
But, "we" are used to removing corroded parts. ( if there not corroded, there has been a oil leak for a while ;p )

( but, i guess.. if your not used to it.. it might look scary (?) )

Body shop? .. mhe..

If ... IF you really want to get rid of it, for the piece of mind sake..
well, technical you could just replace the nuts / bolts. ( i would save the money for something else.. but.. )
Spraying / conserving already rusted parts.. well.. of course, you can.. but.. "mhe" time / cost vs usefull repairs ... i would not ;p

Only thing i would keep a eye on, wheel arches !!!! clean em up, so they don't start to rust. And i have seen some with some nasty rust damage on the hood ( under where the hood-lifts are mounted )
But, they had then some serieus sea / winter weather without cleaning for years then.


Oh forgot, do check the break line connectors ( after the hose ) , those "u turns"
If the nuts / bolts are like this, they are most likely in the same state..
Now.. thats bad... ( they can take a lot , but.. thats the one thing i would check )

[Jdcole82]

Do you lift your car when you check for rust? I don't have a way to lift it and think I may be missing some parts. A lot of parts are covered by plastic though. Any parts in particular I should be focused on?

[Stefan666]

Well, i had quite some repairs so its been on a jack regular the last few months
So as bonus, can see any problems coming.

But, when i bought it, i did bring it to a mate with a proper lift , for a proper inspection.

Well, i would focus really on the "outside" ( top ) if you lack a jack / lift around. and, the wheel arches ... * shakes fist * those dreadfull wheel arches..
Its a weak point in our climate, hard to find one without rust damage .
Exhaust .. but any problems are usually detected by your ears..

Im always a bit .. hesitating to let a garage / shop , who have economical benefits of repairs / broken parts they -might find-
"check if they see a problem".
And i put cosmetics way below mechanical issue's / maintenance

But a "new car" to you ?
( and, by age.. a older car )

1- engine ( service ) .. multi / airco belts, fuel filter ect.. - the works -
2 -brakes ( proper state ) , so as the disc and with the hose's
3 - suspension ( proper state, rear springs not broken ? ) , shocks still ok ?
4- drive train, how the bearings / arms.. no play / shakes , control arm rubbers good shape..


then a long time nothing

67a , see if i can find some rusty nuts that anoy the hell out of me.