Power steering fluid added to brake fluid

I had a short between the ears and added power steering fluid to my brake reservoir on my 2000 F-250 Super Duty diesel truck.

Could that be the reason my brakes went out coming down a mountain about 1800 miles later? (I was not braking excessively. In fact they started acting up BEFORE I got to the mountain.)

At first, the brake pedal would act normal most of the time I hit the brakes. When it didn’t, the brake pedal went in another 3 inches or so, but I had braking, just not power brakes.

I took it to a brake repair place here in Mexico where I had just arrived for vacation. It was recommended by a long time friend.

They drained the entire system, bled it, then took it for a test drive, and now the pedal goes all the way to the floor with no braking action. Luckily the parking brake still works!

In your opinion, do I just need the new “master cylinder” or whatever the thing under the brake fluid reservoir is, or am I in for a REAL repair job?

Oh, even though this truck is manufactured in Mexico in addition to Kentucky, it is not SOLD in Mexico, so no one here has parts.

The owner/guy who speaks English at the shop thought he MIGHT be able to get by with just a diaphragm if he could find one.

I’m desperate, and without wheels.


The master cylinder is shot and soon all the rubber interal brake parts that have been in comtact with the petroleum based fluid will be trashed.

If the PS fluid was added to the master cylinder about 1,800 miles ago–as the OP implies–then the rubber parts in the brake hydraulic system are already trashed.

Anybody can make a mistake when adding fluid, but to not do anything about this mistake for an extended period of time was a VERY expensive screw-up on the OP’s part. I think that the only way to assure reliable braking performance is to replace the master cylinder, the flexible brake lines, and the wheel cylinders or calipers.

This will not be cheap. And, the lack of local parts supplies will likely result in a long delay in making the repairs. However, total loss of braking ability is not something that the OP should take a chance on. Anything less than replacement of all brake parts that came into contact with the PS fluid is…potentially fatal.

May I ask your level of expertise?
Obviously I’m not the smartest OP in the world, but I want to know if yours is the voice of experience, or conjecture?

My experience follows exactly what RodKnox and VDCdriver stated. The petroleum based fluids will begin to make the rubber parts turn mushy, leading to brake fluid failure. I believe you have few options other than to take their advice seriously.

For sure, replace the master cylinder. There are AutoZone stores in Mexico and they can get the part. I suspect Ford dealerships can too…

The P.S. fluid may or may not have worked its way down to the calipers and wheel cylinders…Time will tell.

It was bad enough putting P.S. fluid in to begin with. Driving until the brakes failed before you were motivated to do something about it, well, that’s something else again…

You are the one who destroyed your brake system, not us…Those who post B.S. advise are quickly corrected on this site. I’m a retired ASE mechanic and shop owner who was certified in Brakes and four other specialties…

Forgive my ignorance of how this system works, but I THOUGHT I was replying to VDCdriver. You are ow the third person who joined the “converstation”.
Are you a mechanic? An engineer? the moderator of this discussion? I’m a dumb car driver, but I don’t want to be taking advice from someone with an opinion but no expertise. I’m not trying to insult anyone, just know what level of expertise you, or anyone else who replies is coming from.

Thank you Caddyman!
I drove because there was no choice. I was 50 miles from ANY town, and I was careful as heck.
I’ve admitted my stupidity, and I HOPE the new AutoZone store 12 miles away can get the parts. The Ford dealer in town was like talking to a rock.
I’n not sure what level of expertise the place I took the vehicle to has, but it was recommended by a long time friend, plus the man I’m dealing with speaks English and I speak VERY little Spanish. There was one good sign. He refused to charge me for the two hours he spent on it Saturday because he had not actually fixed anything.
Now if I may ask you a follow on question? After he replaced the fluid and bled it, the pedal went all the way to the floor instead on most of the way. Could that (in your opinion) mean when they flushed the system the “bad” fluid made it to the calipers and wheel cylinders, damaging them immediately, making them HAVE to be replaced?
The reason I ask is if I have to have parts shipped by DHL, I’d rather order too many than too little.
Thanks again Caddyman.

I now live in Mexico 9 months a year, so I know where you are coming from…Good Mexican mechanics are usually VERY good. No parts changers down here…

At this point, I would replace the calipers and wheel cylinders too… Why take a chance at this point?? Since wheel cylinder kits are a standard part, they will be available down here, on the shelf. So a new Master and a pair of calipers and rebuild the rear cylinders. DHL is a good choice of shippers, they get stuff across the border better than anybody…

And remember…“Manana” does not mean “tomorrow”…It means “not today”…Most Mexicans are decent, honest, courteous, gentle people. Things will go MUCH better if you act the same way when dealing with them…How far south of the border are you?

Does this truck have ABS, for your sake I hope not. I don’t know what effect power steering fluid would do to an ABS unit, but i know that ABS can make It very difficult to bleed the brakes.

May I ask your level of expertise?

VDCdriver is experienced and one of our most respected contributors.

I got off the tool road to Tepic near the town of Ruiz. That’s where I noticed the brakes, as my wife had been driving on the toll road until that for the last hour. She had said someting about the cruise control not kicking off properly at one point not long before that.
I stopped and had her press the brake pedal while I looked for fluid squirting out. While I was under the hood looking at the brake reservoir is when I spotted the power brake reservoir and my heart sunk. I then got on the libre to the San Blas exit, went almost to San Blas, the took a left and followed the road to Las Varas, then back on Mexico 15 to Puerto Vallarta. I wanted to get there as we had a week in our time share to stay, plus I’e been coming here since 1987, and know my way around town, and know a lot of full timers down here. Are you anywhere near?
The sun just came up so time to walk 10 blocks to the Frenos place.
Here’s a link to the maps of where I got off. Ruiz is near the bottom. I just didn’t want to drive through Tepic, then the awful road down to Compostela and on to Las Varas that way. Trucks are horrible on that road.

FWIW, I am a certified master mechanic with over 30 years experience. Your problem is not new on this forum.

Anyone have experience on the best way to bleed the brakes with 4 wheel ABS?
I’m in Puerto Vallarta Mexico where this truck isn’t sold, so they have no experience nor access to info from Ford.