Brake Fluid Change??? - Toyota Yaris Forums

CoryM · 12-28-2016, 04:26 PM

Air will pull past the coarse bleeder threads when using vacuum on the bleeder. Especially on rebuilt calipers with poorly machined threads. The threads are not designed to seal at all, and are loose enough that even fluid can pass through them readily when the bleeder is loose (which is annoying because it means when I do flushes, brake fluid drips on the hoist). Just make sure to close the bleeder while there is a vacuum still on it and you shouldn't have any air problems. If you loose vacuum while the bleeder is open, it will pull air back into the brake system. The mityvac may be harder to use than a flusher because of this. The best way to use the mityvac for the final bleed is probably to pump the hell out of it with the bleeder closed, crack the bleeder and then close it again before vacuum runs out. Otherwise you may keep getting air sucked back into the system.

Do not use any petroleum based greased where it can contact your brake fluid or rubber. It will swell the seals and destroy them.

bronsin · 12-29-2016, 09:59 AM

Quote:

Originally Posted by CoryM

Air will pull past the coarse bleeder threads when using vacuum on the bleeder. Especially on rebuilt calipers with poorly machined threads. The threads are not designed to seal at all, and are loose enough that even fluid can pass through them readily when the bleeder is loose (which is annoying because it means when I do flushes, brake fluid drips on the hoist). Just make sure to close the bleeder while there is a vacuum still on it and you shouldn't have any air problems. If you loose vacuum while the bleeder is open, it will pull air back into the brake system. The mityvac may be harder to use than a flusher because of this. The best way to use the mityvac for the final bleed is probably to pump the hell out of it with the bleeder closed, crack the bleeder and then close it again before vacuum runs out. Otherwise you may keep getting air sucked back into the system.

Do not use any petroleum based greased where it can contact your brake fluid or rubber. It will swell the seals and destroy them.

Sounds like an excellent reason not to use a mityvac.

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12-28-2016, 04:26 PM	#1
CoryM Drives: 2009 5-door, 5-speed Join Date: Sep 2011 Location: White Rock BC Posts: 687	Air will pull past the coarse bleeder threads when using vacuum on the bleeder. Especially on rebuilt calipers with poorly machined threads. The threads are not designed to seal at all, and are loose enough that even fluid can pass through them readily when the bleeder is loose (which is annoying because it means when I do flushes, brake fluid drips on the hoist). Just make sure to close the bleeder while there is a vacuum still on it and you shouldn't have any air problems. If you loose vacuum while the bleeder is open, it will pull air back into the brake system. The mityvac may be harder to use than a flusher because of this. The best way to use the mityvac for the final bleed is probably to pump the hell out of it with the bleeder closed, crack the bleeder and then close it again before vacuum runs out. Otherwise you may keep getting air sucked back into the system. Do not use any petroleum based greased where it can contact your brake fluid or rubber. It will swell the seals and destroy them.