Questions and Answers

Nissan Sentra Bad Brake Fluid Q. Question: I heard a constant squeaking noise coming from my front tire area. But every time I would press the brake, it would fade. So I took it in for a brake inspection to two different places. First place said that my brake calipers needed to get replaced. I thought I'd go get a second opinion.

The second place told me that I needed to replace my front brakes. So we authorized them to replace the brakes. They were about done with the car, after flushing and bleeding the brake fluid, when they came back and said that something else was wrong with the car.

They said that the brake fluid was contaminated with power steering fluid. AND now the front brakes have no pressure (basically I had no brakes) and the contamination in the fluid required a replacement of the "brake master cylinder" to be made.

My question is, what happens when my brake fluid is accidentally mixed with some other fluid such as power steering (as they are claiming was mixed into it)? Would this cause the master cylinder to fail and need replacing (after the brakes have been bled)? Would the mixture of brake fluid and power steering fluid run through the system already and I would have gotten a sign of trouble beforehand (before they flushed they fluid)?

The last time the car was worked on before this (for the fluid to get contaminated) was in September 2002 for an oil change.

• 1997 Nissan Sentra
• 1.6 Liter Engine
• Automatic Transmission
• 132,000 miles
• Fuel Injection
• ABS Brakes

Thank you...

A. Brake fluid is a very different fluid from all the other fluids used in a car. It has a very high boiling point and is extremely stable. (I'll give fifty cents to anyone who can tell me what brake fluid is made from!) One drawback is that it is water soluble. That's why it needs to be changed every two years.

If, indeed, power steering fluid, or any other fluid or oil is put into the brake system, it will contaminate the system and cause all the seals in the brake system to deteriorate to the point where they will start leaking.

In any case where the brake fluid has been contaminated in such a manner, I recommend replacement of, at least, the master cylinder because it has the first seals that will go. The seals in the wheel cylinders and calipers will eventually go bad too. But it will take longer because it will take longer for the contamination to reach them.

So if you catch it soon enough, the repair will probably be limited to a new brake master cylinder and a complete brake fluid flush and re-fill. Then I would keep an eye on the calipers and wheel cylinders for signs of leakage every time it goes in for an oil change.