Washer Fluid in Brake Master Cylinder

A few ounces of windshield washer fluid got into the brake master cylinder about 6 weeks and 600 miles ago (long silly story). I’ve not had any warning lights come one, and brakes have been working fine. Took 2014 Lexus in for a 40K checkup, and was told the entire brake system (brake master cylinder, ABS hydraulic control assembly, Front and Rear Calipers & gasket, brake flexible hose replacement and finally brake flush) needed to be replaced at a cost of $7,100. Does that make sense?

Take it to a shop, and tell them what you did.

Then ask that the brake hydraulic system be flushed.

That’s all that’s needed.


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Thank You so much. I will do that. Is it possible that the dealership would be that outrageous?

Appears they thought you asked for a wallet flush vs brake fluid flush.
It does not make ANY sense. Do not return to these robbers but do get the entire system flushed ASAP.

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Not possible, but probable.


Thanks again for your quick reply! I so appreciate it.

Thank you for your reply! I really appreciate it and will be taking your advice and tester’s!

yep, sure is.

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Dealerships often act like quack doctors eying wealthy patients. When in doubt, try the most expensive remedy. That means replacing everything in this case!

As recommended, a good shop would completely flush out the system and refill it with proper bake fluid.
Brake fluid is alcohol, , water and a little bit of detergent, so removing that will leave no lasting damage.

Dealers have more incompetent mechanics than crooked ones. Both are hard on the wallet, but dealers are supposed to know how to do a proper diagnosis and fix.

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Update: My husband called the shop that he’s used for years for his CRV, explained what happened and the mechanic suggested just what you said: He will flush the system and it should be fine…Thank you Thank you Thank you

The dealer may have been concerned about the effect of isopropyl alcohol on the rubber parts in the brake system and water to the metal parts during the six weeks but there is probably no damage done.

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thank you so much for the info!

Thanks! I appreciate your insight into how dealerships may be operating. I’m sure my husband would agree with you; he hates them, but I’ve always trusted them for maintenance updates. But this - I’m so disappointed. But I’m so grateful for the feedback - you all saved us a lot of money!

I use the dealer for warranty work and routine maintenance such as oil changes. Often they come up with an arm’s length list of things to make the car like new again. I smile and tell them I am also not the man I was 20 years ago, but I’m still very capable!

I have found General Motors dealerships the most incompetent in diagnosing problems and Toyota dealers the best so far! But our own mechanic who builds race cars and restores antiques is by far the best.

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Sometimes the Subaru dealership will come up with a maintenance suggestion that is just… over the top.
At that point, I take my inspiration from Nancy Reagan, and I just say “no”.

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I think it’s utterly and completely erroneous to badmouth all car dealerships as being incompetent and/or crooked.

If the car in question suffers a brake hydraulic failure in any component in the near future then one can make a reasonably safe guess as to what the cause was.


This is the crux of the issue. In order to avoid ANY possibility of liability on their part, the default answer is to replace EVERYTHING regardless of whether or not the actual possibility of catastrophic failure is infinitesimally small.

I spend a lot of tie doing Risk Analysis for industry. In industrial plants items get maintained, rebuilt or replaced as needed. In all cases the considerations are 1) Safety and Environment, 2) Loss of production and 3) Nuisance value of a breakdown.

The (1) category deals with the same statistical analysis insurance firms do, and usually is expressed in event per million hours of operation. Mechanical equipment typically fails using a 99.998 % reliability factor, so a 0.002 % chance of failure. .In critical situations, backup equipment is used as well

Car parts built to 6 Sigma quality levels do extremely well. Usually a failure is caused by the Human Factors at play. My 11 year old Toyota has had only 2 light bulbs as actual failures so far.

In the case of a car dealership, the absence of a competent diagnostic technician often results in the owner being taken to the cleaners by the “replace everything when in doubt” attitude. Those mechanics used to be called “parts hangers” because that’s all they really did.

In my area there is an automotive chain that works on the principle of pre-determined “work packages”. If the customer has a problem in a certain area, work package “X” is prescribed, usually with a great waste of unneeded parts and work. A simple front brake problem typically becomes a complete front brake job! This chain simply lacks good diagnostic techs.

You meant to start the sentence “Washer fluid…” The description is of washer fluid, not brake fluid.

Or at least one can make a reasonably safe guess as to what the plaintiff’s expert witness is going to claim the cause was. :wink:

I don’t think it’s proper to impugn all dealership mechanics as incompetent or crooked. That said, it’s not unusual to pay more at a dealership than at an independent - after all, the independent has 3 or 4 bays worth of shop to pay upkeep on. The dealership has acres worth of shop and grounds to maintain.

It’s also not unusual to find dealership service departments that just do whatever the computer tells them to do, which can get you in a bind when there isn’t a DTC available for the problem.

I think in OP’s case either the dealership saw dollar signs, or the dealership’s service writer has been coached by the dealership’s lawyers to insist on removing any possible liability claims, which means replacing entire systems when that wouldn’t be necessary 99% of the time. Or maybe it’s a bit of both.