Changing Brake Fluid - how often, really?

[johnhicks]

Having the pedal go to the floor got my undivided attention. I'll be changing the fluid every two years.

[wimpy]

Originally Posted by Mudfrog

The way I see it, this is a closed system with little chance of moisture intrusion. Imo, there's a problem with the system if the fluid gets contaminated.

My newer VW's manual states to have the fluid changed every 2 years no matter the mileage. It made 2 years last April so I called the dealership to make an appointment to have it changed. The service manager told me it was NOT necessary.

Cast iron is porous & will allow moisture to enter your system. Your VW service manager is both a DA & grossly incompetent.

Originally Posted by HarryStone

Brake fluid is hydroscopic, which means it absorbs water, and that's one of the reasons that when adding brake fluid, the instructions will say to only use fluid from a new, unopened container.

HyGROscopic. As noted, manufacturers recommend flushing fluid every 2 years. I've used Castrol LMA DOT 4 Synthetic fluid for 40+ years, initially when I was SCCA racing.
It exceeds DOT 3 & DOT 4.

Manufacturers recommend 6 year life span for rubber brake hoses. Rubber brake hoses fail internally. They may look good externally with no cracking, but collapse, restricting flow. Royal Brass & Hose & Pirtek have fabricated rubber brake hose for me, cheaper than any alternative.

The speed bleeders work great & enable a 1 person flush. If you're new to the process, start from the furthest point from the fluid reservoir, usually right rear, then left rear, right front, finally left front.

If you have rusted steel brake lines, cupronickel brake line is the easiest to fabricate.

[F4Gary]

I put Speed Bleeders on mine and did a flush in 2018. Pretty easy and I don't think they had ever been flushed before as the fluid that came out did not resemble brake fluid at all.
I've been complacent and need to do it again soon.

[Persistent]

So, what to do is not simple. You are dammed if you do and you are dammed if you don't.

If you open the brake fluid reservoir you risk contaminating the fluid. If you don't open the reservoir you may be ignoring on-going damage. If you change the brake fluid you risk getting contaminated fluid re-installed. Different manufacturers may come up with different solutions.

I worked for a company that built equipment using hydro-static transmissions. This same issue became an investigation and experimentation project.

The conclusion was that some products were better off with sealed transmissions. Letting home owners open and fill would shorten life of the transmission.

Others were better off just hiding the fill port and not recommend checking or changing. This allowed well equipped service shops to make repairs and refill if necessary.

Large commercial equipment had change intervals to get the life desired. This was risky because owners would sometimes try to do it themselves. Almost always DIY resulted in shorter transmission life. Even major service shops often had problems with contamination.

If you are going to change hydraulic fluid of any type, make sure it is done at the most professional shop you can find. Contamination kills high pressure systems.

Actually automotive transmission fluid can be changed by a shop that has the specialized equipment needed. The specialized equipment for the most part prevents contamination.

I wish you good luck and happy trails ahead!

[Minnesota51]

Thank you. I can afford to have it done professionally by experts. So I don't need to do any backyard stuff and, I would probably screw it up anyway since I have no experience. Plus I can't physically get up and down as easily as I once could.

There are people that like to do things themselves just because they're very particular about it. They feel better doing it themselves and enjoy it. I get that.

[wolfe10]

Actually, most home mechanics will do a BETTER job than most shops.


Taking the time to thoroughly clean the area around and above the master cylinder and perhaps covering the area above it with aluminum foil or a sheet of plastic to keep dirt out is not something a shop is likely to do.


Most shops will not do as is best for the master cylinder and suck out the old fluid, add new and stir with a clean metal tool and repeat until the fluid is clean. MUCH better than running the old fluid in the master cylinder reservoir through the whole brake system.


But, it really depends on the skill level (little is needed) vs "care level" of the person doing the job.

[EyezOpen]

I once had the same opinion on brakes&fluids, strange attitude towards brake maintenance. Then I went thru my own braking system after a few downhill eye opener's.

RV brakes experience protracted heavy loads, meaning extreme heat. Heat that cars never experience. As stated above water intrusion happens, that lowers the boiling point,that reducers the brake efficiency, which in turn only generates more heat which degrades the pads which in turn degrades the rotors.....

Heat is the enemy of braking components, changing the fluid every 4 yrs only prevents heat and keeps one focused on the overall health of the running gear.

Brake failure is a very sickening feeling.

[House Husband]

Changing the brake fluid on my MH saved me a lot of time and $$. While changing the brake fluid, I shake the rotors to see if the bearings are adjusted correctly. The LR rotor move a lot. I had a bad outer hub bearing and the differential was filled with shrapnel. I opened up the differential and spent a lot of time removing all the shrapnel. I also found a bad carrier bearing. So after 8 new bearings, a bearing shim kit, 3 new seals and 5 quarts of 75W140, I am back on the road at a cost of $600.00.........Much nicer to be confined to my own home, than being stuck in a motel/hotel waiting on some one else to find the time to repair the problem. Not to mention the cost.

Richard

[amosnandy]

I'll chime in my 2 cents. Yes. Changing the brake fluid every 2 years is a must. I have done it on every car I have ever owned. Watch a youtube video on how to do it. I do mine with just a bottle and a hose, open the bleeders and let it drain. Yup, to drain it may take a gallon.

That said I buy it by the gallon. About $15.00. It is usually used up in a couple of months as my son also has a shop. DO NOT however use it if it has sat in the cold/warm cycle open can. Brake fluid is one of the only automotive fluids you cannot tell if it has absorbed moister.

[Bill Gail]

I change my MH brake fluid and engine coolant on the same schedule as when I replace the tires , 5-6 years .

All other fluids are changed per the Mfr. mileage schedules .

The MH is stored in an enclosed shop and plugged in whenever not in use .

I can see more frequent changes for Full Timers who are on the road alot more than us recreational RVer's .

[ArtJoyce]

I think bleeding brakes now is much more important with ABS. The ABS system has small valves and screens. It's not just water but brake fluid gets dirty from the rubber seals.

I have started bleeding my brakes every few years.

[edgray]

Originally Posted by Bill Gail

I change my MH brake fluid and engine coolant on the same schedule as when I replace the tires , 5-6 years .

All other fluids are changed per the Mfr. mileage schedules .

The MH is stored in an enclosed shop and plugged in whenever not in use .

I can see more frequent changes for Full Timers who are on the road alot more than us recreational RVer's .

May I suggest you read my post above. I think it is just the opposite

To summarize it, I wrote. "The point of this long post is to say it is possible to replace the fluid less frequently IF you drive your coach on a regular basis and don't let it sit too long, especially in high humidity climates. YMMV."

[bigb56]

I change mine at 2 years but I recently bought a tester and checked my Superduty after 2 years and it showed still ok, in the reservoir at least. That truck gets driven rarely but I live in a very dry climate and park indoors. I agree with Brett that a DIY will usually do a better job, that's my biggest reason for DIY and I will regret when I reach the age where I cannot do as much as I can now as it is actually enjoyable for me. I use a power bleeder and new fluid from a metal can and any leftover gets disposed of on the hazardous waste run.

[153stars]

Forgive me if mentioned in all other lengthy posts DOT5.1 is fully compatible with DOT3 absorbs less moisture.and higher boiling point. Meets DOT 5 standards but is not silicone. Do not buy DOT5. it's silicone only for vehicles made for it/ rubber parts and seals ect....