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Will brake fluid corrode aluminum

Will brake fluid corrode aluminum?

There’s pitting on my trailing arms and dust shields, in a peculiar spray pattern.

UPDATE: now that we are done with this trivial question, here’s a pic of the pattern I am talking about. I think it is from water condensation and then the water droplets drying out. It really does seem like pitting… but perhaps not - won’t know for sure until the day I brush it clean…

Brake fluid is essentially non-corrosive. It will not react with aluminum, nor much of anything else. Some car owners replace their brake fluid at regular intervals but this is because the fluid can absorb moisture which does have corrosive properties.

If you see pitting on the trailing arms and dust shields, brake fluid is not the culprit.

Brake fluid will strip paint quickly.

Are the trailing arms and dust shields really aluminum?

@art1966 yes and probably - come to think of it, the only such corrosion (appears as white specks) is on the rear shields, not the front, and the front I think is painted or something.


Sorry, but I gotta disagree with you on this

I know from professional experience that brake fluid will very quickly cause paint to blister and flake off

I’ll give a really good example . . . if you encounter a vehicle with a brake master that was leaking externally, take a good luck at the booster. More likely than not, the booster will have flaking paint right below the master cylinder

I realize that brake boosters don’t have an aluminum shell. They are stamped steel and are painted. In any case, spilled/leaking brake fluid should be hosed off with water as soon as possible. And the cause of the leak should immediately be repaired.

No. Most brake and clutch master cylinders are cast from an aluminum alloy.



I’m not talking about the master cylinder . . . I know they’re made from aluminum

I’m talking about the brake booster and the car’s paint

They are not made from aluminum and the brake fluid will most certainly damage them (the paint, at least)


JuniorMint asked if brake fluid can corrode aluminum. And the answer is no.


@Tester good point - I had forgotten, the BMC is made from aluminum!

“JuniorMint asked if brake fluid can corrode aluminum. And the answer is no.”


Bumping this up (?) because I finally added a pic of the area in question, incase it helps at all.

I don’t think anything in the picture is aluminum.

Brake fluid itself will not corrode metals, but if the corrosion inhibitors in the fluid break down over time, corrosion could occur. There is the potential for moisture to be present. Aluminum is not automatically immune to corrosion. I have seen aluminum exhibit significant corrosion in many marine situations. But, fresh brake fluid is not going to cause it.

“There’s pitting on my trailing arms and dust shields, in a peculiar spray pattern.”

You can see if the shield is aluminum with a magnet.
The white speckles look like salt deposits to me.

I finally got back to this.

the shield shown is not magnetic @PvtPublic @circuitsmith. however, the front set is. go figure. also the front shields are badly corroded, but the rears cleaned up OK.

I wire brushed them real good - still some pits, but I think what happened - like someone said, sorry didn’t cite - some liquid dissolved the brake dust but did not affect the aluminum. The liquid was either water (likely from sitting around with horrendous condensation), or brake fluid spatter.

thanks for the help anyways -even though the answer was in prior to all the other discussion.