[sf1332]

My 2012 Pilot EX-L with 87000 miles suddenly developed a soft brake (I can push pedal all the way down to floor) with minimum stopping power.

Took it to a local mom-and-pop shop, and the mechanic with 40+ yrs of experience told me he's seen this kind of issue only about 3 times: he says rubber seals in the brake system have been corroding because "wrong" fluid has been put in. He should me a gasket right under the reservoir cap that he said he could not put it back because it's been "swollen" too much.

I told him that I don't work on cars (didn't even know which "cap" was for brake fluid!), and all services done by a local Honda dealer. The last service (+annual inspection) was about 5 months ago (only 3500 miles driven since then). He strongly believes that someone made a mistake and put in wrong fluid in the brake system. He quoted me:

1. at minimum master cylinder will need to be changed (about $350-550 range).
2. He would actually want to change all the rubber parts in the brake system (in the calipers, etc) this will be additional $500-$1000, etc. including labor time.
3. He declined to service the vehicle actually saying that I should take it to a local Honda dealer who's been servicing it before.

Advice please?
1. Anyone heard of this type of issues, and was the mechanic right? and what are likely causes and cost estimate to fix?
2. Would a dealer mistakenly put in wrong fluid to top off the brake fluid reservoir (a trainee or someone under influence?)?
3. I have been actually thinking of trading in this vehicle for another thus have seen KBB for this vehicle in $12k to $15k range (but "cash value" might be lower).
4. Would you fix first then trade-in (or even sell) or would you trade-in as is? (presume dealers would take it with known issues).

Any advice/questions would be appreciated.

Thank you in advance.

 

[dr bob]

Issues with wrong-fluid contamination in modern cars are almost unheard of. Unless someone purposely put a petro product in the brake system, the modern materials are pretty bulletproof.

I'd follow his advice on taking it back to the servicing dealer and let them sort it out as part of a workmanship warranty if they recently serviced the brake fluid. Brake fluid changes don't show up on the Maintenance Minder because they are time-based only, and the MM tracks tasks by miles driven. If you have the car regularly serviced by that dealer, they (and you) know when or if they last changed the brake fluid.

His scope of work is likely larger than what you listed. Possibilities depend on the actual cause of the problem, starting with easy stuff like a leak and low fluid level in the reservoir. If the fluid truly is contaminated, the list of affected rubber bits is pretty long. Starting at the reservoir and the master cylinder ($$), fluid passes through the ABS unit ($$$$), then on through rubber brake hoses ($) to the wheel calipers ($$) with rubber seals. A soft or low pedal diagnosis starts at the reservoir for a level check, then the master cylinder for a leaking seal or check valve. The reservoir cap that he showed you has a mini bellows inside that is drawn down as fluid level drops, so that moist air outside is isolated from the hygroscopic (likes to absorb water) brake fluid.

Please share back the results from your dealer visit.

 

[sf1332]

dr bob, thank you for this advice and info. Yes, it's "unheard of" problem. My dealer cannot fit me in for a week, so hope to figure what to do within 1-2 weeks.

 

[dr bob]

I'll qualify my statement above about "unheard of" because it turns out there's no shortage of people who choose not to read a label.

The Pilot brakes are looking for a DOT3 or maybe DOT4 brake fluid. The difference between the two is mainly the boiling point. Other than that they are functionally interchangeable. On the same shelf at the parts store there are bottles labeled DOT5. In addition to a higher boiling point, the DOT5 is a completely different and incompatible silicone-based fluid. It's intended only for very high-temperature duty, and it is totally incompatible with US DOT3 and DOT4 fluids. To use that stuff in a former DOT3 or DOT4 system, all the old fluid needs to be removed, and the system has to be flushed so that there are absolutely no traces of the old fluid anywhere in the system. The installation protocol for the new fluid included degassing it in the container (with vacuum), then evacuating the hydraulic brake system (again with vacuum), and slowly allowing the fluid to be drawn in by vacuum from the lowest points (the calipers, dangling low so it's a full uphill path for the fluid to the MC reservoir). The silicone fluid is thick enough that air bubbles don't come out with conventional bleeding methods, hence the vacuum degassing and fill protocol. But that's a description of how to use it. If you accidentally put DOT5 in a DOT3/4 car, you will see the symptom you describe as a first sign of problems.

There are no DOT5 cars passing through any normal Honda dealer's service bay, so absolutely no reason for them to have the fluid present for a possible contamination accident. More common is an inattentive owner, who buys the best/most expensive fluid on the parts store shelf, and uses it to "top up" the reservoir. Unfortunately, that "most expensive" stuff is pretty deadly to the rubber it touches. Let's all hope that's not what happened to your car.


There's a DOT5.1 fluid that is compatible with DOT3/4 fluids, just add more confusion to the discussion. Does not get along with DOT5 at all.

 

[Tacoma'03Pilot]

If your brakes aren't reliable, they're dangerous. If the problem is as your mechanic described, you may be bleeding brake fluid from multiple points (this is why the pedal is going to the floor). That's an accident waiting to happen, with serious potential consequences for liability if you live in the United States.

I suggest a phone call Monday morning to explain to the service manager (or the general manager, if that's what it takes) that your brakes are failing for unknown reasons, they've done all the work, and they need to get on it. I would have it towed in.

To your questions about trading / selling, if the fluid really is bad I wouldn't consider selling it to a private party "as is", even with full written disclosure.

See if the dealer will fix it for you. If so, you have a sound vehicle and can trade it, sell it, or keep it. If not, consider offering it to the dealer in trade to get rid of your problem and shield yourself from future liability.

 

[sf1332]

Tacoma'03Pilot, thank you for your words of wisdom. I will call again tomorrow (Monday) and try to get in rather than waiting another week.

dr bob, about someone potentially mixing up DOT3/4 vs. DOT5:

Reviewing my records, I found that I had my PILOT inspected (annual in PA) and oil changed at Monro Muffler/Brake in 9/2017 (at 77190 miles). This is the only other potential place that might have topped off the brake fluid (as I can assure you I did not buy something like that (DOT5) and topped off by mistake as the only fluid I put in the car has been the windshield wiper fluid).

What worries me is that the service record from Monro indicates that "declined by the customer: Brake System Flush" meaning that they did check the brake system...and perhaps did top it off with (wrong) fluid. Would this small amount of wrong fluid take 10k miles and 1.5yrs to corrode the rubber seals?

 

[sf1332]

oops the mileage at 9/2017 service at Monro was off. It was at 66857 miles (ie, 20k miles ago).