Contaminated Brake Fluid = $4K Repair


$100 Site Donor
Staff member
Oct 10, 2010
Virginia Beach
His brakes started performing peculiar over 4 months ago and recently became dangerous, sometimes grabbing - other times requiring multiple pedal pushes. Sometimes the pedal almost goes to the floor. This is a small shop he has trusted for many years. Calipers, rubber hoses, master cylinder, ABS unit (?), proportioning valve......what else?

We all know that parts and labor costs much more than DIY. And, a shop cannot cut any corners on something like this due to liability. You really think he is getting hosed?

EDIT - he thinks the fluid contamination happened when, or before he purchased it = more than a year ago. I can add more once I see the repair bill.
The brakes are dangerous right now.

Not due to old fluid.

Due to contamination.

Many of the responses here fail to consider that fact.

The mechanic can try a flush, but giving it back to the customer without restoring full, safe, operation is criminally negligent.

Franky, once the seals and rubber parts are swollen, then, yes, it’s likely that every part has to be replaced. Master cylinder, ABS module, calipers, hoses.

$4K sounds about right for all that.
Nov 20, 2006
There are 3 areas of vehicle repair you do not ever take chances on, steering, suspension and brakes. If I were doing this for myself on a one year old vehicle I would pull every component off, replace every rubber part inc hoses with OE and flush the metal lines with IPA or Acetone. This can be time consuming and more than a some shops would want to get into based on time alone but I am not paying myself labor.

Saturated EPDM rubber (Ethylene, Propylene, Diene Monomers) will not "recover" by flushing, period. It is ruined and dangerous in service, the only repair is to replace the part or replace all the rubber components in the parts. At this age the calipers, MC and ABS unit will have a minimum of wear will most likely only require seals not pistons.
I would verify the system is contaminated which is not difficult and repair it properly before putting it back on the road. If he want a second opinion flat bed it to the dealer, do not drive it.

Jan 2, 2004
With brake fluid and PS fluid being sold by the same brands and having the same straw-like appearance, mix-ups are common. The only recourse is replace everything, flush the hard lines with brake clean and start over fresh.

I knew of someone who added Prestone PSF to the MC reservoir of his truck and he complained about the brakes locking up. As soon as I saw the rag, swollen lid gasket and the bottle of Prestone PSF I knew what’s up. I replaced the MC but also told him to be prepared to replace anything else.
Feb 27, 2009
down in the park
It's not the fluid causing the sinking pedal, and replacing the fluid won't cure it. There's a leak somewhere, either a valve not closing properly or a seal that's unreliable. Been there, done that... abs unit needed replacing, no matter of flushing fluid helped although my boss had me do that first a number of times.
Jun 3, 2005
Santa Barbara, CA
Something like that happens you can close the doors and file bankruptcy right away.
I think a lot of people here are missing the view of a shop that has to pay insurance. If it were to come to court, the shop would be considered the "expert" who should not have given the advice that flushing a contaminated system was an acceptable repair.

Also, and please no-one here misunderstand me when I say this: this would be one of those situations where you quote really high to either make them go to someone else, or make it worth the possible headaches down the road.
Apr 26, 2005
Under the hood
Liability insurance is not an excuse to practice negligence.

Doctors and lawyers carry malpractice insurance, financial and other fiduciary professionals carry E&O insurance, those in construction carry liability, workers comp, bonding, and so on…

Wouldn't want to find oneself in a situation where a claim may be made against any of those policies any more than a claim against a mechanic's policy.

If a doctor sees that little lump, and says "nah, you're alright, no biopsy needed, go rub some lotion on it and you're good to go," only for you to get cancer and die, you're still dead. But he had insurance!

If the mechanic says it's fine, and a flush is all that's needed, try it out, and then you go and collide with something, or someone else, you and the other party are still injured, or dead.
Jan 14, 2015
If local vo-tech or Junior college should want to get it for training, They typically do it for the cost of parts. Takes a few weeks though.

They only teach how to fix it right. If you let it go long enough the master cylinder will leak into the brake booster and kill it too.