Questioning brake bleed order

[mwrohde]

For starters, I'm talking about a 1998 2WD with 4 wheel ABS. I don't know about other models or factors.

I've been bleeding the brakes on this truck 1) Passenger rear, 2) Driver rear, 3) Passenger front, 4) Driver front. The theory here is that it's longest run first, continuing to shortest run.

The location of the ABS pump had me wondering if that was actually longest to shortest. Yesterday I went to the junk yard to buy an ABS pump and confirmed my suspicions.

From the master cylinder two hard lines emerge. They go directly across the firewall from the driver side master cylinder to the passenger side ABS pump. From the ABS pump 3 lines emerge. The shortest drops strait down to the passenger front. That means the passenger front should be the *last* one bled, not 2nd to last.

The next hard line emerging from the ABS pump goes back across the firewall to the driver front. That would make it the second shortest run, so the second to last bled.

The third line coming out of the ABS pump actually feeds both rear wheels. I'll admit, I haven't traced that one to check, but if that line splits in the middle of the rear axle like I think it does, then both rear wheels are the same distance, and it shouldn't matter which is bled first.

What am I not understanding about the goals and procedures for brake bleeding?

 

[jstim]

For starters, I'm talking about a 1998 2WD with 4 wheel ABS. I don't know about other models or factors.

I've been bleeding the brakes on this truck 1) Passenger rear, 2) Driver rear, 3) Passenger front, 4) Driver front. The theory here is that it's longest run first, continuing to shortest run.

The location of the ABS pump had me wondering if that was actually longest to shortest. Yesterday I went to the junk yard to buy an ABS pump and confirmed my suspicions.

From the master cylinder two hard lines emerge. They go directly across the firewall from the driver side master cylinder to the passenger side ABS pump. From the ABS pump 3 lines emerge. The shortest drops strait down to the passenger front. That means the passenger front should be the *last* one bled, not 2nd to last.

The next hard line emerging from the ABS pump goes back across the firewall to the driver front. That would make it the second shortest run, so the second to last bled.

The third line coming out of the ABS pump actually feeds both rear wheels. I'll admit, I haven't traced that one to check, but if that line splits in the middle of the rear axle like I think it does, then both rear wheels are the same distance, and it shouldn't matter which is bled first.

What am I not understanding about the goals and procedures for brake bleeding?

As far as I know on the back when I bled mine, I just started on the rear passenger side first. It works fine, but thats my .02 on bleeding them.

 

[LittleCaesar]

So I have to ask what the dealer said concerning the soft brakes.

In twenty years I have always gone off furthest from MC to closest. It has always worked for me, except on the X5 I tried once, where the ABS computer could only be activated by the dealer to allow fluid to flow.

 

[gamefreakgc]

For record, I've bled a 4Runner from front to rear before, and the other way around. It doesn't really make that much of a difference if all you are trying to do is flush the lines and remove air bubbles.

 

[mwrohde]

So I have to ask what the dealer said concerning the soft brakes.

I haven't taken it yet. I'm stubborn. Still trying things. I'll post back on that thread as I try things. I'm planning on putting the ABS pump on tomorrow morning.

In twenty years I have always gone off furthest from MC to closest. It has always worked for me, except on the X5 I tried once, where the ABS computer could only be activated by the dealer to allow fluid to flow.

This was my original point. RR, LR, RF, LF is *not* furthest to closest in terms of length of brake line run, but it is the commonly recommended order.

 

[LittleCaesar]

I will be pulling for you, and to get your son on the road. Why those valves fail to close is beyond me. Bad fluid I would guess. At least it isn't an 01-02, which even at the yard is much more $$$.