When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello , I am not a experienced mechanic and have basic skills around cars . I just installed new caliber’s and used the motive bleeder that the forum recommended (worked great ) however i committed a rookie mistake, and didn’t notice my master cylinder had crud and some rust on the bottom . My question is if I clean the master dry will that introduce air bubbles back in the system again and have to re bleed. Also what can I use to clean it with Thanks
Absolutely it will. At no point should a MC be allowed to run dry, or a bench bleed will be needed.
I think at this point without any photos of the MC, I would use a brand-new turkey baster and remove what you can from the rez. Place towels around the MC and have a catch can for the contaminated fluid. As you draw the fluid down keep adding fresh DOT3.
See how it goes. Might work, might not.
You will not be able to clean with Acetone unless the MC is removed from the vehicle.
Absolutely it will. At no point should a MC be allowed to run dry, or a bench bleed will be needed.
I think at this point without any photos of the MC, I would use a brand-new turkey baster and remove what you can from the rez. Place towels around the MC and have a catch can for the contaminated fluid. As you draw the fluid down keep adding fresh DOT3.
See how it goes. Might work, might not.
You will not be able to clean with Acetone unless the MC is removed from the vehicle.
it was clear before I stirred it up . I thought if I didn’t pump the brakes it would be ok
Don't be so paranoid. Air goes up. Fluid down. Suck it out. Wipe it out but don't fill with a cleaner of any kind. Refill a quarter of the way. Place a rag over the top of the master. Depress brake pedal and let it "Snap" back. Like when you drop a clutch. Slide your foot off the pedal sideways and let it Snap back. Do this 3 or 4 times and any air bubbles will snap up.
check for brake pedal firmness and repeat if necessary. Properly fill master. Install cover.
I do this almost every bloody day on motorcycles.
works the treat.
AIR GOES UP!
Don't be so paranoid. Air goes up. Fluid down. Suck it out. Wipe it out but don't fill with a cleaner of any kind. Refill a quarter of the way. Place a rag over the top of the master. Depress brake pedal and let it "Snap" back. Like when you drop a clutch. Slide your foot off the pedal sideways and let it Snap back. Do this 3 or 4 times and any air bubbles will snap up.
check for brake pedal firmness and repeat if necessary. Properly fill master. Install cover.
I do this almost every bloody day on motorcycles.
works the treat.
AIR GOES UP!
If you suck it all out. Your not removing fluid from the bore. As long as you don't touch the brake pedal you will NOT get air in the bore of the master. Air goes up. Not Down!
just don't touch the pedal while your cleaning!
Cam33, this ^^^^^^ is not the best advice, but you can do what you want.
I always thought you can run the master dry as long as you don’t pump the brakes.. air goes up not down however let’s get this thing right . Anyone else please give your opinion
OP, Turkey baster will work, I'd get one of those suction devices, like the one below, it has more suction and you can stir things up and then suck it out while its in suspension.. You can also use it for your differential and I once overfilled a car with oil and attached some fish tank hose to it and sucked it out of the dipstick..lol But, I have to say, if you have visible rust in there, I'd be looking to replace the Master cylinder. I lost my brakes once and it's an adventure I don't want to repeat...
As far as the Air going up debate, if that's all that is needed then why do we bench bleed the M/C before we install it. Most Motor cycle M/Cs are pretty simple single piston types and a little suction on the caliper bleeds them out fast. My car had some grey stuff in it that made the fluid a little dark, a couple of flushes with that giant hypo thing and you can see the bottom ...
Master cylinder help
