mixed brake fluids, now have gunk in system

Installed a new slave cylinder so had to bleed the clutch circuit. Used the rest of my super blue fluid, then my Pentosin, and then had to switch to Penzoil (all open containers on my shelf). I know better than to use open containers but just really wanted to get the car on the road & figured I'd flush the entire system later this summer once I knew everything was working. Look at these pictures. See the crap in the bottle that I drained the fluid into and see the spots on the top of the inside of the master cylinder reservoir? It's waxy consistency and I cannot get it out. Fluid is dark because of ATE Super Blue, not because filthy or rusted. I've bled the whole system with 3 bottles of Motul 600 and still having crap coming out. The brakes feel normal to me but the clutch doesn't feel quite right. I'm really not sure what to do as I do not think I can get it all out by bleeding more. I wouldn't dare track it as I'd be worried once the brakes get hot that they will fail. All the fluids are glycol based DOT 4. What in the world happened and what can I do about it?

Is it possible one of the opened containers got contaminated while it was on the shelf? Did anyone else have access to the shelf or containers? I've never seen this sort of thing happen by mixing different brands of DOT4 brake fluid, so I doubt if it's an incompatibility problem, it's more likely contamination somehow. I don't think you'll like my suggestion - but in this case - I think the entire system has to be flushed out - probably with alcohol. It's that or disassemble it and clean the components before reassembling. Alcohol has always been the go-to cleaner for the internals of brake hydraulics, and shouldn't attack any of the seals, but I would still be a bit cautious and only leave it in the system long enough to start brand new pushing brake fluid through. If you don't have a diagnostics tool capable of activating the ABS/PSM pumps - you'll need one so you might as well spring for it (the Foxwell NT530 with Porsche option works quite well for this.) Disclaimer - I'm not a brake hydraulics engineer, nor a professional mechanic. Everything I've learned has been via the school of hard knocks and we know how that can go - so do not take my advice as gospel - check before doing anything. Fasten seatbelts and keep hands and feet inside the car to prevent injury.

Delete please..

A power bleeder should push the system clear. No idea where to get one. We borrowed one from the Chevy dealer a while back. Not hard to do, put an air hose around 50 psi, I think, on the bleeder tank and hook the bleeder to the master cylinder. We did activate the ABS.

I believe in his second photo he's showing the cap of a power bleeder on the top of the reservoir, so apparently that hasn't been enough to push the crap out. FWIW - I'd be hesitant to put more than 2-bar on the power bleeder (30PSI) since the reservoir is a press fit into the master cylinder and excessive pressure can push it out of the master cylinder, spraying brake fluid all over the place (this happened to a friend. School of hard-knocks.) Good practice is to put a tie-wrap around the reservoir and cylinder so it can't come off the cylinder.

A quick search online says that the waxy stuff is common for a brake fluid that has absorbed too much moisture (eg, as with open containers). Reference: waxy substance in brake fluid master i just changed my brake fluid and when i was done i noticed a waxy substance dried and flaking off the float for the master cyl. before i started the... www.ferrarichat.com Waxy/Milky substance in brake fluid Thread titled -Waxy/Milky substance in brake fluid- started by mrceotri on 10-06-2013 in How To's and Q & A's www.motohouston.com And many other similar threads. I would also suggest flushing, as Don recommended. I don't think there's any other way other than taking it all apart and cleaning (as Don also suggested). Bottom line, it seems you have contaminated brake fluid in the system, and the only way to recover is to get it out. Given the amount of moisture that is probably in there, you may have to do a lot of flushing, and then wait a while for it to re-absorb the moisture in the system (time/temperature) and then flush again. You may want to get a brake fluid tester to prove this is the case, as it's a cheaper alternative versus just flushing based on "public opinion". For example: https://smile.amazon.com/PTE-Tester-Calibrated-Brake-fluids/dp/B005HVG4GQ - see if the current fluid is "bad" and then flush and flush until it's "good"... then test again after some time to see if it got "bad" again (as I think it might).

Perhaps worth reviewing: Brake System Flush - Pelican Parts Forums

Thanks for responses. Guess I'll pick up a bunch of denatured alcohol and Pentosin brake fluid (best stuff I can get locally) and do full flush including ABS. I have Durametric for that. Got nothing else to do today anyway.

Dear Sir, I am new to Porsche and came across your thread while researching what maintenance I will do on my future 718 . I might be wrong here but there was no discussion on here of which Pentosin brake fluid you use. Most modern cars with advanced ABS like my M cars use Pentosin LV (Low Viscocity) I believe super blue is the thicker stuff that was from the old days when thicker was better. I compared the specs of BMW OE brake fluid with super blue and LV one weekend when I pulled out all the fluid from my reservoir and my car was on jackstands only to realize that the BMW fluid bottle was almost empty. I forgot I had used it up recently and the dealer was closed. So I did the research so I could get German fluid on sunday. I later comfirmed that LV is the correct one. If you look at the Porsche brake fluid bottle it says, as I suspected, Low Viscocity so you should be using Pentosin LV DOT4 not super blue. I am not sure if this contributed to your possible issues, but if you are going to flush, I recommend you get the Pentosin LV so that the ABS system operates as expected. I can imagine thicker fluid not circulating as well within the tiny ABS ports and perhaps causing it to get sludged. I was shocked to find out no one in the parts stores even knows they carry LV. I have had to explain it to parts people multiple times and to make matters worse, because they didn't understand what the LV stood for, they would actually recommend the older style thicker stuff for the new European cars. I hope to at least get people to start noticing these things. The flushing article mentioned references Super Blue as well but it looks to be a 80s/90s 944. Super Blue would be correct for the older cars but not for newer advanced ABS ones. Best wishes and let us know how it turns out. I do not recommend putting anything other than clean LV fluid to flush out the gunk at first. If it doesn't work, then try it foreign substances. I don't know what alcohol will do the rubber seals in the master cylinder and slave cylinder. The safest route is to just flush out with the correct fluid. Best wishes.

I'm pretty sure these ABS systems are not that sensitive. I used Pentosin Super DOT 4 which I've used before. It's pretty low viscosity as-is. I saw the LV on the shelf next to it but it's $5 more per liter and only has wet boiling point 9 degrees higher than the Super and the same dry boiling point. The denatured alcohol did not dissolve the waxy crap in the reservoir as I'd hoped. I stuck my finger in and wiped it off where I could but you can't get anything in the front half of it due to the design of it. I bled quite a bit of alcohol through the clutch hydrolics, then followed it up with about 2/3 liters of the Pentosin. Clutch seems to feel right and brakes are firm (they have been the whole time). Guess I'll drive it a while and maybe do some hard stops to get them hot and make sure no fade. It's probably alright. I doubt I'd gain anything by flushing even more fluid through the clutch or brakes. I think the only thing that would clean it out better would be brake cleaner and I'm worried it would ruin the seals in the whole system. I really don't want to rebuild master cylinder, slave cylinder, ABS module, and all calipers so I'm calling it good.

It's your car but perhaps for others out there, you say that it has worked fine for you but you have sludge in your system so to us it actually appears that something has not worked out correctly in your case. I have never seen anything that bad. I am just some bloke on the internet but sir, the German engineers that designed that system and the german company that built that system designed it for Low Viscocity brake fluid for a reason so if you don't believe me, no offense taken, but perhaps consider much smarter people that are telling you to use the recommended fluid. Anyway, at least some others out there in Porsche universe will know that low viscocity is the fluid recommended by Porsche and the brake system manufacturer. Best wishes.

Yeah, the 987.1 and .2 don't spec LV fluid, they spec regular DOT 4. Anyway, assuming they're all glycol DOT 4 fluids you used I have no idea what to tell you: all DOT 4 should be compatible. If the fluid were old and had absorbed water I would think you would've noticed it being dark or gelled when you put it in. So I'm kinda stumped here. Is it possible that's something from your pressure bleeder? Like, I dunno, the plastic or the hose are degrading and flaking off or something?

I agree I would have thought it would have been dark or milky or something. The fluid was pretty old though. The pressure bleeder is a good theory but I was only using it for pressure. I did not pour the fluid in it at all so that's probably not it. I'm going to go with Schwinn's suggestion in post #6. Let it sit in there, drive it, get it hot. Then bleed some more and maybe do that a few times. Hopefully the gunk will mix into the fluid with the contact time and some heat instead of sticking to surfaces in the system in globules and then be able to be bled out. I learned my lesson about old fluid though. Never will use old fluid again. I figured the worst that could happen is you have a little moisture in it and it won't be good for the track. I was planning to flush new fluid back through this fall before a track day.