Metallic Flakes in Brake Fluid (1 Viewer)

[Outbounders]

Replaced the brake lines this weekend and with that came new fluid. The fluid that was in the system is only a month old as I replaced calipers then. When I was bleeding the brakes after replacing lines and fluid, I noticed tiny metallic flakes in the fluid. What could this be indicative of? Master cylinder failure? Thanks in advance

 

[Road Apple]

How large are the flakes? Do they settle or remain suspended. Check the fluid that was installed to be sure it’s correct. If the container is metal, check that the container isn’t shedding metal flakes.

 

[Outbounders]

The caliper pistons or the ABS control unit have metal to metal contact. You might a failure or be missing an o-ring from the recent install.

How large are the flakes? Do they settle, or do they stay suspended? Do you see any rust?

Check the fluid that was installed to be sure it’s correct. If the container is metal, check that the container isn’t shedding metal flakes.

Flakes do not settle. Does not appear to be rusty at all, just looks like a really nice paint job on a low rider. Missing o-ring? I did not have any o-rings in my installation of lines or calipers. Something I should be concerned about? Maybe ABS is the reason for my mushy brakes..may need to start research on that.

 

[smritte]

I've been doing brakes professionally for decades. Which includes a ton of ABS systems. I don't think I've seen metal flakes. Never say cant happen though. Not alot that can "chew up" metal in there. The only thing that I can think of is the ABS pump. Your calipers have rubber seals with very little metal contact. Master is the same. Are you sure it just didn't have a metallic sheen?
Flush the system, cycle the ABS and do it again.

 

[Road Apple]

Do a vaccum flush of the brake calipers to remove any remaining metal flakes. If there are fresh shiny flakes that are localized to one caliper, inspect that caliper.
If flakes are found in more than one caliper, then the ABS control unit should be inspected.

 

[Road Apple]

When you flush the system, follow bleeding the wheels with bleeding the load sensing proportioning and by-pass valve.

 

[elhombre]

The simplest explanation is that the new lines have metal in them from the manufacturing process. Go to Walmart and buy a couple to three quart bottles of brake fluid. Spend some money on this brake bleeder. Flush it all out.

IF something is going bad, it will soon start leaking fluid, then replace it. There is no way I would take the ABS system apart for "inspection". How would a person know that something is worn out in there?

No O-rings in the system for lines. There are copper seals at the caliper where the banjo fitting screws into the caliper, but no O-rings used at the stainless steel flared line connections. ( A purist would say there are O-rings that seal the pistons in the calipers, but those are not on the lines you replaced)

Master cylinders "only" go bad one of two ways. They leak internally, or the rear seal leaks and fills up the brake booster with brake fluid. Failure of rubber seals means no metal shavings. (Never say "only")

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[Wyatt Pine]

I am guessing that the new lines and maybe your new calipers had some metal dust from manufacturing. I would flush the brakes again and I wouldn't be too worried unless it keeps happening or there is a change in braking performance.

 

[fjbj40]

I've been doing brakes professionally for decades. Which includes a ton of ABS systems. I don't think I've seen metal flakes. Never say cant happen though. Not alot that can "chew up" metal in there. The only thing that I can think of is the ABS pump. Your calipers have rubber seals with very little metal contact. Master is the same. Are you sure it just didn't have a metallic sheen?
Flush the system, cycle the ABS and do it again.

When you say “cycle the ABS” are you saying to drive it one side on gravel one side on pavement and jam on the brakes? Or are you talking about jumping the wires to the ABS unit to activate the pump?

Thanks

 

[smritte]

When you say “cycle the ABS” are you saying to drive it one side on gravel one side on pavement and jam on the brakes? Or are you talking about jumping the wires to the ABS unit to activate the pump?

When you first start your vehicle, the abs runs two test's. First is key on and second is once vehicle hits 1-3 mph. On the second test it fires off the pump and tests the valves. You can just do that or hit the brakes on water or dirt.

One of the classes I now teach is ABS/traction control. I threw your issue out to my class last night and let them chew on it. I used it as a diagnostic problem. For the most part everyone seemed to agree if the metal came from wearing the calipers or master it would take a long time. The pump was the only thing that could have been that fast. This is assuming something you replaced didn't have metal inside it. One of the guys asked if the original brake fluid could have had metal and you flushed all out except what was trapped inside the ABS system. The first time it does the pump test, the metal would now be mixed with the new fluid. I had to agree, that was more likely than pump wear.
If you have access to the metallic fluid, see if its magnetic. The pump should be magnetic. Everything else wont be.
FYI, I have never seen or heard in any of my ABS classes of the pump causing this. Never say cant happen though.

As for your soft brakes, assuming you did a good job originally when you flushed it, I see two possibilities.
1. The rubber brake hoses you installed flex more than your originals. Mine was horrible when I replaced mine and I switched over to braided steel. All good now.
2. There are valves in your ABS system and a spring loaded piston called an accumulator. When you trigger abs the accumulator is used as fluid storage and to hold pressure. You have a valve that stay's closed during normal usage called an isolater. If this is worn out and is leaking, when you step on the brake pedal, fluid will bypass and go into the chamber. When you release the brakes, it flows back. The brake pedal feels like air or a bad master. This commonly starts happening over 200k miles. The valve wears, faster if you don't change your brake fluid. The old brake fluid forms acid and slowly eats things. Also, the pump itself seals the other end. I guess its remotely possible a worn pump can cause fluid to bypass there also, causing a soft pedal.
None of the ABS possibilities can be tested on our systems.

As is posted above, flush and see if it comes back. Take it one step at a time. If the soft brake pedal turns out to be the ABS, your going to replace it with new (good luck there) or remove it from the system.

 

[smritte]

There is no way I would take the ABS system apart for "inspection". How would a person know that something is worn out in there?

Its too bad you cant service an ABS modulator. Their not designed to be able to. Something about it being a safety item and all that. The accumulators/valves I referenced are a common high mileage problem and commonly misdiagnosed.

Some of the manufactures give access to the back of the accumulator piston. There would be two plugs you remove and stick a pick or solid wire in the hole. Start vehicle and press brake pedal hard. If one or both wires push's out, the isolator valve(s) are leaking.

I tore down one from a 96 cruiser to see where the accumulator was in the housing. I did this because I wanted to see if there was a spot I could drill an access hole for this test. As far as I can see, it cant be done safely.

This forum is filled with posts on "I cant get the air out". The common diagnostic is "there's air trapped in the ABS". Gallons of fluid later, the OP removes the ABS and the problem is gone. The most likely issue was the isolator valve worn out.
A long while ago, one of the abs systems ford used, was having this issue around 50k. The symptom was soft pedal and people mostly threw master cylinders at it first not knowing of the test plugs.