power steering fluid in the brake fluid resevior

[Brian]

Hi guys, I have a friend that accidentally poured a good amount of power steering fluid in the brake fluid resevior thinking that is where it was meant to go. Do I need to flush her brake fluid, or will that be okay as it is? 2007 chevy impala 3500 v6 engine.

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[Donnie]

I’d suggest a bleeding the brakes until it is just brake fluid in the system. I do not believe Power Steering fluid has the same boiling point as brake fluid, which could lead to ineffective braking.

[Mason]

You’ll need to drain the entire brake system asap. The first thing power steering fluid will do is disintegrate the rubber port seals inside your brake master cylinder. They will expand until they’re blocking the ports inside the master cylinder and keeping the fluid from returning from the lines. In other words, the brakes will be permanently engaged and you’ll be stuck wherever you are (hopefully you weren’t moving too fast when the bakes locked up).

Various websites say to immediately disassemble your brake lines, wash them out and replace all rubber parts, as damage to the rubber parts begins as soon as you put the power steering fluid in there. However, I don’t think this is necessary as long as it hasn’t been too long since she did it and she hasn’t driven too much. I’ll let you be the judge of that. But regardless, you definitely need to completely flush out the system, and there are a few threads on here as well as an ETCG video on how to do that right. It wouldn’t hurt to check out any rubber components you think are worth looking at as well. And lastly, when you finish flushing the system, make sure the right fluid goes in there lol

ETCG video: https://www.youtube.com/watch?v=V5O_pbC8R2E

Hope this helps & good luck!

[none]

Yeah, it will swell O-rings, but it also softens and emulsifies them to the point that the fluid pushes around them. If you get a lock up condition, they’ll soon go soft shortly after. At my shop, the policy is to require everything goes that has a rubber anything in the brake system when you pour the wrong fluid into your brake fluid reservoir. If you want to gamble on power steering fluid not getting to the calipers, at least don’t bleed the fluid down. Find a way to push the fluid back up to the master cylinder. I really recommend you just replace all the calipers and brake hoses though. Do thoroughly clean out the steel brake lines. A couple cans of brake kleen will do the job. Also be ready for the likelihood that you’ll need to replace your ABS pump module. You’ve got two choices for the pump module and I found you some part numbers for both. I also found part numbers for the electronic control modules as well. I don’t think you’ll need to replace the electronic side, but the part numbers were there so I added them on contingency.

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