Brake fluid sludge
 

Hi friends,

I recently did my own brake fluid flush for the first time. I used some of the online DIY/videos. Seems like everything has turned out well, pedal is less mushy.

I had a hard time discerning when there was a change in color between the old/new fluid - and I used a lot of new fluid. Next time I might use the blue fluid to see if it helps, but I heard that it can stain the reservoir.

Anyways, my main question was with regards to the reservoir. While emptying it, I noticed what I was taking out was full of floating "boogers" let's say. Then I peeked into the reservoir, and saw the filter was full of this white-ish sludge type of goop. I did my best to get it all out, but probably some was left behind. I couldn't figure out how to remove the filter so I just left it.

It all sort of floated to the bottom of my catch bottle. I couldn't see anything else suprising in the reservoir, and actually there wasn't much sludge in there.

But I am wondering, what is this sludge? I am sure it's a product of infrequent fluid flushes, as the last one was probably 4 years ago and "done"" by the dealer (I just came into possession of the car so don't blame me!). Should I be worried?

Actually what came through the lines at the wheels was sludge-free. I didn't even get much in the way of bubbles. Maybe some minute particles here and there that I really had to look hard to see, but that's all.

So far so good, for anyone on the fence about trying to DIY, it wasn't hard at all. Just took me a lot of time doing it for the first time.

Thanks everyone

FYI - You can no longer get that "blue" fluid and you can thank our stupid regulations for that. And yes, that "blue" fluid does stain the reservoir, but it self-unstain after about 2 fluid changes with the regular stuff.

Sorry - can't answer your other question as I haven't ran across this on mine.

I concur on the staining comment. I've been blue-free for awhile and the rides have lost the embedded dye..

I have been running Motul DOT 5.1 synthetic brake fluid for several years in my BMWs at flush time.

https://www.amazon.com/Motul-100950-.../dp/B07KYWH2W8

https://images-na.ssl-images-amazon....SY340SH20_.jpg

Less propensity for water absorption, higher boiling point and longer service life, IMHO.

This fluid in conjunction with SS/teflon brake line upgrades has given me a much firmer pedal feel and braking action. :dunno:

To each their own.

Mike

Be careful not NOT mix DOT 5 fluid with DOT 3, DOT 4 etc. fluids.

DOT 5.1. is OK though...

DOT 3, 4 and 5.1 are glycol-based.

It's a bit confusing... :confused:

DOT 5 is silicone-based and will NOT mix with the others - it can result in blocked brake systems. :yikes:

EXACTLY!!!

It is critical that folks considering a synthetic brake fluid in our ABS brake system equipped vehicles use DOT 5.1 :thumbup:

Mike

Was just reading the spec sheets for this Motul DOT 5.1 - it's boiling point is lower that that stated for their DOT4.... (DOT 5.1 dry 272C vs DOT 4 dry 328C) :confused:

K, I stand corrected, however, do you find DOT 5.1 to be higher than DOT 3?

Mike

Wasn't out to correct anyone - I would have sided with your original statement too. :thumbup:

Just thought it was weird that the "higher" spec fluid was rated lower. Devil is in the detail though, as they don't state the "wet" boiling point. It seem the DOT 5.1. remains consistent at 272C while the DOT 4 performance drops off as it absorbs water - they state the wet boiling point as only 204C, so it's clear that the DOT 5.1 holds up better as it ages.

So you are correct - out of the bottle the DOT 4 is better but as soon as it's in service and starts absorbing water, it's boiling point drops.

The DOT 5.1 is as you said... :thumbup:

Thanks for the additional insight on this critical fluid wpoll :thumbup:

Mike

This is why I always suck the old fluid out first.

Then fill the reservoir with either:

1. Blue ATE fluid (which is no longer available).

2. Regular generic DOT4 fluid from local store (such as BrakeBest brand from OReilly). I have used BrakeBest DOT4 fluid for > 10 years in my Volvos, BMWs without any issues.

Is there any detriment to having the blue stain? It sure would have helped me figure out when the transition from old fluid to new fluid was,

Blue is just a colorant.
Similar to washer fluid, Gatorade etc.

Good to hear, thanks for the reply. I think I will try to find the blue kind for next flush, to make sure I do it properly.

Unfortunately, that "blue kind" is no longer available in the good US of A - thanks to our stupid regulations :(

The few unopened containers you do find... are like $100+ for ATE Blue. It's crazy. At the risk of sounding like a conservative (a favorite disclaimer of mine ;)) US regulators think everyone are idiots. Honestly, 99% of people willing to add brake fluid to their cars... already know what and where to add. The last 1% can then take their cars to a local indy and support the local economy some more after they screw up. :D At least then, they will have learned something.