Curiosity on brake fluid

[50yr Street Mech]

I am amazed that these tests even exist !!! Learn something new everyday on this forum. That's a noob for you LOL .... Back in the day, all my friends thought I was a wacko bleeding out brake fluid. They never did such a thing. Eventually, they all started blowin master cylinders and couldn't understand why, or blowin wheel cylinders, or frozen calipers. Told them all, take it to a shop, I'm too busy at my regular job to be playing around with you're stuff...And I really was busy. Had 2 jobs back then. Con-Ed Utility during the week, and 20 pharmacy delivery cars to maintain on weekends and holidays. No wonder I blew my back up .....Paying for it now with back surgeries

 

[50yr Street Mech]

Hey Supton, You wanna know what I did with all my " Salt Belt" calipers. Filled the pistons with high temp silicone, let it cure, and Viola !!!! No more seized/rusted out calipers. No blown seals, nothin. Worked great !!!!!

 

[supton]

I've thought of packing the piston with some red rubber grease, get something in there to seal it, behind the rubber boot, but just haven't bothered (yet). Some day.

I could see trying to seal the piston as slowing down the water intrusion.

 

[50yr Street Mech]

It works !! Grease might leach out from heat. Never heard of rubber grease. But the silicone works great. Gotta be resourceful in the rust belt If the pad sits inside the piston with those springy clips, I just take a utility knife and carve out some notches for them.

 

[Vercingetorix]

So if you don’t believe brake fluid circulates, testers are useless.

 

[50yr Street Mech]

I don't know who you're referring too, but brake fluid does circulate. Not a whole lot, but it does.

 

[Mechanician]

It doesn't "circulate", but a little gets exchanged every time the pedal is cycled.
I'm not following how - filling/sealing the cavity of a caliper's piston will help keep a caliper from seizing.
How does that work?

 

[nthach]

I use German long-life fluids when I can, so every 2-3 years… if I’m not lazy. Else, it’s every brake pad swap or “major” fluid service, whichever comes first.

One car has Prestone Max DOT3 that looks like aged Toyota OE, and there’s less than 100K on that fluid. Prestone calls it a 100K fluid. The RXh has ATE SL6 in it. The Camry will get a flush soon, also ATE or Bosch ESI6.

 

[edyvw]

Every 2 years, on the family vehicle and my wife's car.
On BMW, if I track it 2-3 times, in the summer, and if I don't, I just skip one year. I skipped two summers of track time, so flushed BMW this summer after skipping last summer.

 

[BC1]

I noticed the brake fluid I get from Walmart likes to turn green, instead of just slowly turning dark.

I just did two of my cars and they were green also. Two years with Supertech DOT 3.

 

[Arc]

Just as a curiosity what everyone's approach is to brake fluid swaps. I am not as religious on brake fluid as I am on other maintenance items. I generally do a full fluid swap when I change pads or shoes, or if I have the wheel off for some other maintenance such as struts or ball joints or the like. Just curious what other approaches there are.

Whenever a line breaks and all the fluid leaks out. Thats how the rest of us electricians do it.

 

[50yr Street Mech]

In the salt belt, the caliper piston corrodes from the outside in, eventually causing rust on the inside too, or worst case leaking. That rust on the inside of the piston prevents it from being pushed in, or you may just tear a seal. The salt belt rust is ridiculous. Gets into every little bit and cranny, even a perfectly sealed caliper pin ! I hate the salt belt and will be moving in 8 years. It has eaten many of my cars to the point where there are holes in the frame. Every spring I have to perform a salt inspection and touch up areas with paint or undercoating.

 

[Mechanician]

In the salt belt, the caliper piston corrodes from the outside in, eventually causing rust on the inside too, or worst case leaking. That rust on the inside of the piston prevents it from being pushed in, or you may just tear a seal. The salt belt rust is ridiculous. Gets into every little bit and cranny, even a perfectly sealed caliper pin ! I hate the salt belt and will be moving in 8 years. It has eaten many of my cars to the point where there are holes in the frame. Every spring I have to perform a salt inspection and touch up areas with paint or undercoating.

New to me, I've never seen that, I would think the piston is so thick it would never rust through. The problems I've seen are usually caused by the seal tears you describe, often from poor repair work while pressing the pistons back into the caliper.
Such as not making sure the dust seal is deflated back into proper shape, and it gets pinched.
Or from twisting the rear pistons back in, and twisting the dust seals up with them.

 

[Starving Electrician]

Whenever a line breaks and all the fluid leaks out. Thats how the rest of us electricians do it.

Haha yeah I live in Florida there are 15 year plus old vehicles with original fluid waiting on that change indicator to pop.

 

[Starving Electrician]

I’m bad about this one. I do it when the brakes get done. I don’t top off the reservoir so when the fluid level gets around min I know it’s time to do the brakes.

Thats me to the letter. I live in Florida so rusting and salt is a non issue. I've seen 15 year old or older vehicles on their original brake fluid.

 

[iCurious]

2-3 years brake flush. Before each winter, clean and relube caliper slide pins with silicone paste.

 

[Exhaustgases]

I'm a suck the old out put some in person. I just don't like to make more problems for myself.

 

[Starving Electrician]

I'm a suck the old out put some in person. I just don't like to make more problems for myself.

Yeah you are better off doing nothing at that point. That is actually rusking causing problems not saving them. The fluid in the calipers is still old, still full of water so more prone to boiling and rusting out the pistons.

Brake systems don't circulate fluid like a power steering system or a cooling system so that is a complete waste of time, effort, and money. Just stop doing that you are risking introducing contamination to the system to gain zero benefit and buying fluid for no reason.

 

[A_User55555]

Flush Every 3 years/36K miles

Every 6 months I turkey baster the reservoir and refill it. Does it really do anything? I don’t know. But for $3 of fluid and 5 minutes of my time, I see no harm

 

[Exhaustgases]

Yeah you are better off doing nothing at that point. That is actually rusking causing problems not saving them. The fluid in the calipers is still old, still full of water so more prone to boiling and rusting out the pistons.

Brake systems don't circulate fluid like a power steering system or a cooling system so that is a complete waste of time, effort, and money. Just stop doing that you are risking introducing contamination to the system to gain zero benefit and buying fluid for no reason.

If that is true then the fluid in the master cylinder Reservoir would never get dirty or dark. Explain how clean fluid will introduce contamination? There is a reason that gravity bleeding works. There is good benefit to it, its getting some new juice.