Coolant in brake system!

[1998Exp]

This isn't about an Explorer, but brakes are brakes, so I am hoping to get a word of wisdom from someone who has encountered this challenge before.
Here is the story: my better half took her Kia for a long trip and somewhere along the road decided to check fluids. Ended up adding about 3 oz of (premixed) coolant to the brake reservoir (which wasn't even low on fluid to begin with), then driving about 2000 miles.
I am going to flush the system the best I can, but wondering about possible damage already done. Any advice will be welcome!

 

[SoNic67]

I would be worried about corrosion. If calipers start to leak, you will know it.

 

[Bobmbx]

Use a turkey baster to suck as much from the the reservoir as you can before you start the flush. The less you allow into the system, the less you have to flush out.

Luckily, brake systems are not recirculating hydraulic systems, which means virtually every drop of coolant is still in the reservoir.

I assume you know how to properly flush a brake system. If not, just say so and we'll get you through it.

 

[SoNic67]

Removed joke because some people are uber PC.

They always end up on my ignore list.

 

[Bobmbx]

Is coolant heavier than brake fluid? In this case it already would be in the system...

I'm sure there's some creep, but why push dirty fluid into the pistons if you don't have to. The challenge will be the ABS.

He needs to do a full flush, not just a fluid exhange. In fact, I'd flush the existing fluid, wait a week to let the brake fluid absorb what water is left, and then do it again.

 

[colintrax]

Use a turkey baster to suck as much from the the reservoir as you can before you start the flush. The less you allow into the system, the less you have to flush out.

Luckily, brake systems are not recirculating hydraulic systems, which means virtually every drop of coolant is still in the reservoir.

I assume you know how to properly flush a brake system. If not, just say so and we'll get you through it.

This ^
And after the bleed I wouldn't be too concerned. Maybe a second bleed next week just to be sure. But I think it'll be ok. Coolant does have stuff in it to prevent corrosion... and she couldn't have added a whole lot. I mean how many cars are rolling around with 200,000 miles and still got the original brake fluid. A fairly insignificant amount of water isn't going to cause any issues.

Maybe before the next set of pads/rotors just toast the brakes to boil off the water? Doesn't hurt to do some spirited driving for you know... maintenance lol

Sonic thank you for editing your first response. Much appreciated

 

[Flash]

Just to re iterate: Coolant won't cause corrosion so you're safe there.
Just flush it all out, refill and flush again later if you want to and you'll be fine.

The only thing that would have happened is reduced resistance to brake fluid boil which might have had serious consequences on a mountain road.

It could have been worse, she could could have put in oil, but then oil isn't green like brake fluid.

Brake fluid should be totally flushed out occasionally anyway.

 

[my98nnj]

Just to re iterate: Coolant won't cause corrosion so you're safe there.
Just flush it all out, refill and flush again later if you want to and you'll be fine.

The only thing that would have happened is reduced resistance to brake fluid boil which might have had serious consequences on a mountain road.

Brake fluid should be totally flushed out occasionally anyway.

^^^This

Brake fluid is hydroscopic (absorbers moisture) by nature. Flush the system and you should be good to go.

 

[lobo411]

I don't see the problem. Brake fluid is yellowish, and antifreeze is kinda yellowish. It mixes, right?

 

[swshawaii]

Could have been MUCH worse. Like power steering fluid.

http://www.agcoauto.com/content/news/p2_articleid/251

 

[96firephoenix]

I'd be more concerned with what Else she may have done. I know a guy (aka, I have his old car in my garage for spare parts) who knew that you should see coolant when you open the Radiator cap, and knew that you had to get the right color coolant... what he didn't know was the difference between rad cap and oil cap. Kid you not, he filled the crankcase with coolant. then drove 100 miles with A) 3 gallons of coolant/oil mix in the crankcase and B) no coolant in the radiator. I drained a quart and a half out of it when it first went up on blocks. factory speck is 13 quarts.

I don't see the problem. Brake fluid is yellowish, and antifreeze is kinda yellowish. It mixes, right?

So long as you don't put green coolant in the amber brake fluid...

 

[1998Exp]

Many thanks to all who responded! Even though she is an experienced driver, it was the first time she attempted any maintenance on her own, and decided that the brake reservoir was the coolant overflow bottle... Luckily, the brake fluid was at the max line, so there wasn't much room to add anything - a couple ounces, at most. Might have been much worse had she put engine oil or steering fluid in there. We all live and learn, I guess.

I ran almost a quart of fresh brake fluid through the system, bleeding all four calipers well past the point when clear fluid started coming out. Intend to do this again after driving the vehicle for a couple hundred miles. So far no problem with braking. Hope it stays that way...

 

[Bobmbx]

Many thanks to all who responded! Even though she is an experienced driver, it was the first time she attempted any maintenance on her own, and decided that the brake reservoir was the coolant overflow bottle... Luckily, the brake fluid was at the max line, so there wasn't much room to add anything - a couple ounces, at most. Luckily, she did not have any steering fluid with her, but might have been much worse had she put engine oil in there. We all live and learn, I guess.

I ran almost a quart of fresh brake fluid through the system, bleeding all four calipers well past the point when clear fluid started coming out. Intend to do this again after driving the vehicle for a couple hundred miles. So far no problem with braking. Hope it stays that way...

For your peace of mind, your brake performance will not be degraded in any way; you don't have to worry about brake failure. The only concern was a long term issue with corrosion, which has been resolved with the fluid flush.

Buy her an ice cream cone and laugh about it.

 

[97MarkVIII]

Many thanks to all who responded! Even though she is an experienced driver, it was the first time she attempted any maintenance on her own, and decided that the brake reservoir was the coolant overflow bottle... Luckily, the brake fluid was at the max line, so there wasn't much room to add anything - a couple ounces, at most. Might have been much worse had she put engine oil or steering fluid in there. We all live and learn, I guess.

I ran almost a quart of fresh brake fluid through the system, bleeding all four calipers well past the point when clear fluid started coming out. Intend to do this again after driving the vehicle for a couple hundred miles. So far no problem with braking. Hope it stays that way...

Your worried about nothing like someone else said brake fluid is hygroscopic. Who really changes their brake fluid every couple of years. Some bottles of brake fluid say once opened discard any unused fluid after two weeks.

 

[ranger7ltr]

Well brake fluid picks up all kinds of crap...

Your worried about nothing like someone else said brake fluid is hygroscopic. Who really changes their brake fluid every couple of years. Some bottles of brake fluid say once opened discard any unused fluid after two weeks.

This is an example of my Explorers' brake fluid after a couple of years of use...I know there was nothing added to this brake fluid other than clean fluid from an unopened container back in 2012 when I did new rotors, pads, and parking brake shoes...The right side bottle is what was drained out last month...Now I drive a lot of miles in a year [avg 70 k] so maybe there is more exposure to dirt and contamination but I have done the brake fluid flush in my cars and trucks every 2-3 years and it always looks like this...

I did a clutch on my wifes' car that is 11 years old and it had been 2 years since I changed her cars' brake/clutch fluid and the old fluid looks just like this as well and the clear fluid was the start of what I flushed through the system as a clean catch...And the clutch and brake fluid share the same reservoir so it gets used quite a bit even more than just the brakes...

Obviously you can do what you want but when brake fluid starts to turn darker it is picking up contamination and it will affect the seals and cylinders in that system...And introducing a water and eythyl gylcol mixture, even a small amount, would have me draining the system, flushing it with fresh brake fluid, and hoping like hell that replacing/rebuilding master or slave cylinders and calipers wasn't necessary but looking out for dragging brakes and or non releasing clutch cylinders as a direct result of the antifreeze introduced to the system...