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Bleed brakes old fluid

686 Views 5 Replies 4 Participants Last post by  spiderserie4
Changed the pads on my brakes this weekend. Noticed the brake fluid was really dark. Checked service records and couldn’t find the last time it was changed. Likely more than 5 years. I know it needs to be changed but I’m worried about clogging the lines or master cylinder. MC was changed 7 years ago.

Front bleeder valves look good the back not so much. Any recommendations for opening old rusty bleeder valves?

thanks for your help trying to solve this fluid problem without creating bigger problems.
86 spider
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Need to bleed the brakes ASAP. You don’t want to have to change the wheel cylinders too. Spray the bleeder screws with penetrating oil them soak overnight. Use a box end wrench to break them loose. One big bottle should do it. Do not use old fluid that has been laying around. Only use fresh and sealed bottle of fluid. Dot 3 should work great.

Ken Smith
You're unlikely to clog anything. Dark fluid has absorbed a lot of moisture, so the biggest risk is probably rust in the bores screwing up the seals. I'd recommend against bleeding by pressing down the pedal, since if you go past the normal pedal stopping point the seal can pick up rust and crap from the unused portion of the MC, and then your MC is toast (ask me how I learned this).

I use a deep six-point socket to break the bleeders free with less risk of rounding them off. Letting them soak in penetrant a bit is probably a good idea: I generally don't do this since I don't want the potential for oil contamination, but in your case a stuck bleeder seems a higher risk.
Thanks Gubi and Ken. Agreed on flushing asap thus my post.
But if you don’t recommend pedal bleeding how should I do it?

I know the pattern is passenger rear then driver rear then passenger front then passenger front but my passenger rear is the worst of the bunch. Driver rear isn’t great either. How bad is it to start with the front?
Pressure bleeder or vacuum bleeder would be safer. You can use the pedal, just put a block of wood or something under it to limit the travel.
I always suck out the old fluid from the master reservoirs and fill with fresh before bleeding and thus try avoid pushing any gunge through the master cylinders.
With the clutch master it is a bit easier and you can also easily wipe clean any gunge collected in the reservoir bottom.
The brake master has 2 compartments, and you can't get to the second.
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