Pretty much as the title states, what could this black sediment be? The caveat here is that I just replaced the master cylinder and reservoir on the car in question (09 Mazda) last month, so I'm a little lost as to how all this junk ended up in the reservoir... My only thoughts are a seal already gone bad on the new master cylinder?
What is this black sediment in the brake reservoir?
- Thread starter Johan1
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Could it possibly be mold/fungus/scuzz?
If there was dirt in the ABS unit, ......could migrate 'up stream' to the reservoir??
Reach in and sample some.
If there was dirt in the ABS unit, ......could migrate 'up stream' to the reservoir??
Reach in and sample some.
I'm inclined to think that perhaps there was some dirt in the abs system. While driving I had to activate the abs a couple of times as I did a complete flush of the system (old fluid wasn't replaced in a long time by previous owner), to make sure I got rid of all the bubbles. It's only after the abs activated that I got this sediment showing up.
I can't exactly sample what's in the reservoir as there is literally no access given the design of it. I can remove the reservoir and dump the fluid out and add fresh fluid and then see, but I'm slightly hesitant as my understanding is it would be good idea to replace the seals too. Mind you, these are brand new seals so I should be able to remove the reservoir with no issues
Possibly rubber from inside hoses and caliper, ABS seals.
That’s what I was thinking as well. No point getting hung up on what it is, just get it out of the system.
Please reread my first post... I just said I installed a new master cylinder last month and did a complete brake flush... and by complete, I literally flushed over 1 liter through the system until all lines were crystal clear. What's point in doing another flush if the problem is going to possibly reappear
I read your post and I know the fluid is new. That doesn’t change the fact that you need to flush the system again. Maybe drive on a gravel road some more to activate the ABS, maybe it will loosen some more stuff.
I see what you're saying, it never hurts to flush but the idea was that before doing that again, I wanted to see if others have had similar experiences, to possibly pinpoint and fix the culprit. That way if I do another flush, the problem won't reappear. I'll start with cleaning the reservoir regardless and topping off the fluid and going from there. New rubber lines will help for sure too
Pull off the reservoir, dump the fluid, flush with new fluid, put it back on, fill it up. Done. If more sediment appears, repeat.
^^Is it not the case that ABS systems can and should be activated before and/or during a brake fluid flush?
There are contacts you bridge to activate the ABS pump, no?
I need to do mine.
There are contacts you bridge to activate the ABS pump, no?
I need to do mine.
I dunno, but I wouldn't be alarmed. I'm with @Trav that it's from rubber degradation somewhere.
I've never really handled that stuff, but it looks very fine when I've seen it in systems myself.
I think it was just leftover in your system and got stirred up from the recent work. Unless you do an extensive flush I think it's difficult to get this 100% out of a system where it's present. It seems to cling to inner surfaces somewhat.
Personally, if the brakes work well, I'd ignore it. The clean fluid from your recent work only magnifies the presence of the debris.
I've never really handled that stuff, but it looks very fine when I've seen it in systems myself.
I think it was just leftover in your system and got stirred up from the recent work. Unless you do an extensive flush I think it's difficult to get this 100% out of a system where it's present. It seems to cling to inner surfaces somewhat.
Personally, if the brakes work well, I'd ignore it. The clean fluid from your recent work only magnifies the presence of the debris.
Not sure about other cars, but I looked at the service manual for this Mazda and there was no such mention, although logic would dictate that yes the pumped should be activated to get fluid flowing through it properly
Most of my vehicles have a little bit of residue like that too. I never worry about it. Anymore the only flush I do is if I have to replace and bleed something. The only brake problems I encounter are the old 2 ton trucks with junk parts and an occasional rusted line.
