[Sirrotica]

The line rusted from a plastic loom that retained road salt resulting in a pinhole in the line. It rusted from the outside in, not from the inside out. I've owned the truck since February of this year and use it for storage on my property. It's not street driven, but still requires brakes to be driven in it's limited capacity as a mobile storage unit.

I'm not concerned about possibly breaking a bleed screw off to exchange brake fluid on a truck that reaches maybe 5 MPH in my backyard,, but thanks for pointing out the obvious.

FWIW, I've never followed the 3 year brake fluid exchange in my own vehicles, and the lowest mileage vehicle I own is a 1999 GP with 111,000 miles on it. Most of my street driven vehicles range from 200- 300,000 miles on them, I probably know a little bit about vehicle longevity and upkeep after taking care of customer vehicles, as well as my own fleet for over 50 years.

I also run my oil for 30-40,000 miles, also not typical in conventional maintenance schedules, but if you properly filter motor oil, you don't have to keep dumping it to keep the oil, and engine clean inside.

I'm not disputing that brake fluid with a DOT 3 is hygroscopic, it is without a doubt, but letting a vehicle sit without regularly being driven is much more denigrating to a brake system, such as hobby cars commonly on this forum.

The water, and sludge definitely settle in the lowest portions of the brake system causing corrosion and deterioration of all components in the system. Exchanging brake fluid taken from the highest point of a caliper (the bleed screw) isn't going to remove anything from the bottom of the caliper cylinder, is it?

All that being said, I'm not concerned about draining, and refilling the brake fluid in this vehicle.

[Kenth]

Originally Posted by Sirrotica

Exchanging brake fluid taken from the highest point of a caliper (the bleed screw) isn't going to remove anything from the bottom of the caliper cylinder, is it?

Not if you bleed by gravity only.
I have found the fluid inlet often sits lower, close to the bottom of the "well", than the bleeder screw.
Change the fluid is best done by the "two person" method or pressurize the master cylinder or using the vacuum method at the bleeder valve.
The bad fluid needs to be pushed or sucked out of the system.

FWIW

[mgarblik]

Gravity bleed to refresh the fluid would work like this. You would remove the old fluid, as much as you can from the MC reservoir. You can use vacuum or even swab it out with paper towels. ( a real mess). Then fill with fresh fluid and keep refreshing it as you gravity bleed. The bleeder is always at the top of each hydraulic unit, wheel cylinder or caliper. Fluid line is always below the bleeder. It may not be 100% perfect, but you will get most of the old fluid out with some patience. When I do a flush, I use a vacuum bleeder to save time and exchange more fluid faster. But I ALWAYS finish with a gravity bleed because I want all the air out and a firm pedal. We have to teach 1 person bleeding because no shop is going to let 2 people at $125.00 an hour each bleed someones brakes. Also, most car enthusiasts work alone.

[Sirrotica]

Originally Posted by Kenth

Not if you bleed by gravity only.
I have found the fluid inlet often sits lower, close to the bottom of the "well", than the bleeder screw.
Change the fluid is best done by the "two person" method or pressurize the master cylinder or using the vacuum method at the bleeder valve.
The bad fluid needs to be pushed or sucked out of the system.

FWIW

I've rebuilt plenty of calipers/wheel cylinders that were flushed by the 2 person method that were loaded with sediment. I always rebuild any brake components myself if the core is salvageable, so I've been inside of many hydraulic brake systems. If I can buy a kit for the vehicle I rebuild the part myself, simply because I don't trust the rebuilders. Unless the vehicle is low mileage, they all have sediment in them

Sorry, not buying that your going to remove all the crap in a caliper just by bleeding them with 2 people, I've seen the results myself.

Here in Ohio we have high humidity, and road salt 3-4 months of the year, flushing the hydraulic portion of the system could get you a tiny bit more life from the system, too many negative things in the environment here that just replacing fluid won't help.

One more thing, due to the road salt (recently we started getting liquid calcium, which is even more corrosive than just road salt) we live with year after year, the bleed screws are usually frozen, trying to bleed them may end up, either a very expensive proposition (parts replacement), or labor intensive drilling the bleed screws out and trying to save the core) when the bleed screw shears off.

Try explaining to your customer that you were going to flush the brake fluid for them, and now the bill is $500 because of the damage you did trying to save them money by flushing the brake fluid.

Did you save them any money overall? Did you make any money, or did you donate a lot of time, and not get paid for it?

That goes over like a lead balloon, who pays the bill? Do you eat the parts, and labor to keep the customer? Or do you charge them for parts, and labor, and piss them off so they never come back?

Explain to them up front that the flush could be between $50 to $500?

If it makes you feel better to flush systems, then have at it, the parts wear no matter how much you flush the system. I don't recall seeing any vehicle go 200,000 miles with out rebuilding/replacing something in the hydraulic portion of the brake system.

[Ben M.]

Originally Posted by Kenth

Change the fluid is best done by the "two person" method or pressurize the master cylinder or using the vacuum method at the bleeder valve.
The bad fluid needs to be pushed or sucked out of the system.

Whenever I've done brakes that were old or cruddy and the customer didn't want to replace the parts, I pull the bleeder screw, clean it out, and attempt to clean out the bottom of the wheel cylinder or caliper of as much as I can (or at least free up the hole). Once I've done that I get clear plastic tubing and a coke bottle, stick clean brake fluid in the bottom to cover up a significant portion of the bottle and hose, then push the pedal inside the car to force nasty fluid and trash out. Once the fluid flows out of the bleeder into the hose cleanly, that side is done and I repeat with clean fluid for the remaining bleeders. Then I finish it up with a gravity bleed to make sure the air bubbles are gone and the pedal is nice and firm.

Takes longer, but it gets done right to me and the fluid is all fresh inside the lines and the majority of the trash is gone.