Will
Will UltraDork
11/19/20 5:33 p.m.

Is the procedure for vacuum bleeding brakes different from doing it the old school way with one person on the pedal and one on the bleeder valve? I've always done it starting with the wheel furthest from the master cylinder, but my Mityvac instructions say more than once to start with the wheel closest to the master cylinder.

This is the first time I've ever heard someone say to do it this way, and I can't imagine why it would be any different.

jfryjfry (Forum Supporter)
jfryjfry (Forum Supporter) Dork
11/19/20 5:49 p.m.

Not sure why mitivac says that but some vehicles have their own order.  My z06 has something weird that I believe comes into play when using the factory computer to actuate different abs valves

ColoradoBob
ColoradoBob New Reader
11/19/20 5:51 p.m.

I've always heard the recommendation for starting with the corner farthest from the master (ie the longest brake line), but I have never heard a reason why it matters. 

I pressure bleed with a Motive pressure bleeder and just start at one corner and work my way around the vehicle

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
11/19/20 6:24 p.m.

it probably mattered back when one master cylinder output was split to go front/rear and then each of those was split to go left/right, and would probably depend on how the tubes were routed, ie high spots etc.  i can't say that i know for sure.  

dps214
dps214 HalfDork
11/19/20 6:29 p.m.
AngryCorvair (Forum Supporter) said:

it probably mattered back when one master cylinder output was split to go front/rear and then each of those was split to go left/right, and would probably depend on how the tubes were routed, ie high spots etc.  i can't say that i know for sure.  

I think it made more of a difference when the system was two main lines that then split off to each wheel, rather than the vast majority of current systems that are four individual lines straight off the master. I usually do furthest away first a) out of some weird superstition ("just in case it makes a difference somehow") and b) to get the most time consuming one out of the way fist and to get an idea of how much fluid the whole system is going to take to make sure I'll have enough.

zordak
zordak Reader
11/20/20 9:04 a.m.

The idea of starting farthest away from the master is so you do not push an air bubble into a wheel that you already bled. At least that is the explanation I got from the auto shop teacher in high school.

Professor_Brap (Forum Supporter)
Professor_Brap (Forum Supporter) UltraDork
11/20/20 9:07 a.m.
zordak said:

The idea of starting farthest away from the master is so you do not push an air bubble into a wheel that you already bled. At least that is the explanation I got from the auto shop teacher in high school.

This is how I understand it also

sergio
sergio HalfDork
11/20/20 12:25 p.m.

Some cars bleeding order is RR, LF, LR, RF. I would use the manufactures recommended order.

Keith Tanner
Keith Tanner MegaDork
11/20/20 12:41 p.m.

Fun fact: the wheel that is furthest from the master cylinder on an old LHD 88" Series Land Rover is the driver front. They were made to be fairly easily built as either LHD or RHD and the Brits prioritized RHD in a car designed primarily for export. As you do. So the brake lines are convoluted in LHD format to say the least.

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