Is there such a thing as too rusty?

David S.
By David S. Wallens
Jan 2, 2023 | rust, rust repair, Shop Work, Discussion, Rust Removal

Rust. It’s up there with death and taxes.

When you see it, do you run and hide or fire up the welder, roll up your sleeves and get to work?

Have a great save regarding rust? Let’s see it.

 

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Comments
Colin Wood
Colin Wood Associate Editor
1/2/23 10:36 a.m.

I'll be the first to admit that I don't have much experience working on cars, but I feel like it's important to remember that at some point, all the "rust-free" examples will disappear.

I know that if I want to play with old cars in the future, I'm going to have to deal with fixing the rust. 

Appleseed
Appleseed MegaDork
1/2/23 10:56 a.m.

Or move. Rusty in California is near mint in Minnesota.

alfadriver
alfadriver MegaDork
1/2/23 11:09 a.m.

There's a huge difference between a super rusty 1938 Alfa vs. a 1968 Alfa.  One would be restored with 100% certainty, even if the body doesn't exist anymore.  The other will probably be left to turn into something else.

So the answer really depends.

Actually, many think the rust of my '99 Miata is too much- it would be fine for most pre-80 cars people like.  And for me, it's the only car I bought new, so I'm happy to work on it.  I've not had a monthly payment on it for almost 20 years now.

BTW, while getting rust off of fasteners is really important and cool- what about surface rust on body work?  How does one hold the rust treatment on it for hours at a time?  And also how does one treat the back side of a weld?

Mr_Asa
Mr_Asa UltimaDork
1/2/23 11:37 a.m.
alfadriver said:

BTW, while getting rust off of fasteners is really important and cool- what about surface rust on body work?  How does one hold the rust treatment on it for hours at a time?  

How bad is the surface rust you're talking about?
Cause.... here's a how-to

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
1/2/23 11:47 a.m.

IMO if fasteners are rusty, replace them.  If they are rusty then the plating is gone, if you don't re-plate then they will rust very quickly.

I used a chemical derusting on a set of head bolts for a 351C and the bolts were as rusty or worse inside of a week.  Nothing to protect them from shop humidity.

BoxheadTim
BoxheadTim GRM+ Memberand MegaDork
1/2/23 11:49 a.m.

I think with the Mini in the picture, the answer is "never, unless the VIN plate rusted away". After all, you can get new bodyshells and they're likely cheaper than repairing all that rust.

I think with other bread and butter classics that don't have that kind of parts availability, the boundary for me is if I can find better condition metal for less than it cost to repair what I have. At some point one has to admit that even for a hobby that doesn't make much financial sense, there are probably restorations that make even less sense.

I've been watching a German YouTube channel for a while that mostly deals with "Youngtimers" (which is what the German classic car people call stuff from the 80s and 90s, especially the ones that aren't eligible for historic plates yet). The main guy on the channel talks a lot about putting cars back on the road even if that means using the hot metal glue gun to put on another stamp size piece of metal, as the alternative is often to junk the car (keep in mind the pretty stringent inspections in Germany). And they've lost a lot of bread 'n butter classic family cars etc because of that. So I guess in the end it's do what you can and yet another incentive to learning to weld.

alfadriver
alfadriver MegaDork
1/2/23 11:56 a.m.
Mr_Asa said:
alfadriver said:

BTW, while getting rust off of fasteners is really important and cool- what about surface rust on body work?  How does one hold the rust treatment on it for hours at a time?  

How bad is the surface rust you're talking about?
Cause.... here's a how-to

That's about where I would change from treat to replace- I have a few places where it looks that treating will be fine- there are no holes.  I'll give that a try.  Thanks!

 

alfadriver
alfadriver MegaDork
1/2/23 11:58 a.m.
Pete. (l33t FS) said:

IMO if fasteners are rusty, replace them.  If they are rusty then the plating is gone, if you don't re-plate then they will rust very quickly.

I used a chemical derusting on a set of head bolts for a 351C and the bolts were as rusty or worse inside of a week.  Nothing to protect them from shop humidity.

Has anyone tried using rust treatment to get fasteners apart?  I may try that on my Miata's header bolts.  But I'll change the nuts, and maybe the studs if they are really bad.

NOHOME
NOHOME MegaDork
1/2/23 12:20 p.m.

Big fan of new bolts when doing a resto. 

 

However, in some cases the fasteners are devoted to a specific use and not easy to replace. Good example would be doing an interior or an engine rebuild. The best tool by far for this is the vibratory bowl filled with plain old sand-box sand. I give it two days in the bowl and they come out spotless. Also works for small brackets and other bits. Bought mine for under $100 on Amazon.

 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
1/2/23 12:41 p.m.
alfadriver said:
Pete. (l33t FS) said:

IMO if fasteners are rusty, replace them.  If they are rusty then the plating is gone, if you don't re-plate then they will rust very quickly.

I used a chemical derusting on a set of head bolts for a 351C and the bolts were as rusty or worse inside of a week.  Nothing to protect them from shop humidity.

Has anyone tried using rust treatment to get fasteners apart?  I may try that on my Miata's header bolts.  But I'll change the nuts, and maybe the studs if they are really bad.

I tried soaking some engine rotors in Evaporust to unlock the side seals.  Didn't work.

Really annoyed at this because they are mythical 12A rotors with unworn seal slots.  But the engine was stored outside without sealing the ports up, and the rust inside was horrible.

 

I did work with someone who used a hydrochloric acid dip to unseize a flagpole bearing.  All it had to be able to do was move, so he neutralized it, pumped it full of grease, and called it good.  I didn't want to acid dunk the rotors because it would potentially damage them.

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