ABS Brake Bleeding Problems

[skippermccoy]

My truck is a 1990 RRC with ABS. I am not getting any fluid to the rear at all. The lines are not blocked or kinked I can push fluid thru them all the way to the caliper.When I removed the line to the rear pass side from the booster no fluid will come out at all even with pump on and pedal pressed.

The only caliper to bleed out fine was the passenger front. The driver side is not pushing any fluid either unless you open the line to the caliper up. So it is probally time for a replacement on that one.

Where to look next?

 

[jims95]

Check if you have a proportioning valve in your brake system. If you do and it is sticking, it can limit fluid flow to either the front circuit or the rear circuit.

I just finished doing a complete brake job on my wife's 1998 D1, because the proportioning valve was stuck. The front brakes were completely down to the backing plates, and the rear brakes were only 1/3 worn. I dismantled the proportioning valve and found wear marks on both the piston and the housing, wear it was sticking.

Hope this helps.

Jim Lupinetti

 

[LRflip]

Jim,

Did you dismantle and clean then reassemble? Or did you dismantle, see the issue, then replace? Im having this issue on my 98 D1 and its becoming dangerous on the trails. Bled my brakes a while ago and noticed no fluid bleeding from the rears....Fronts working fine.

Thanks,

Matt

 

[ptschram]

The proportioning valve on the Classics is on the front of the master cylinder assembly..

I'm afraid that before we go jumping to conclusions, we should really make sure the pump/accumulator/master cylinder are all doing their jobs. But, that would require some high-pressure test gauges.

 

[LRflip]

PT, I guess I didnt even realize that this is the RR tech forum but, either way Im working on my 98 DI...Is it located in the same place?

Both my front brakes bled and operate fine.

I don't have any high pressure test gauges PT! I need a bit more of a DIY fix...

 

[az_max]

I vote for bad M/C. You should be able to remove the line going to the rear to verify the line isn't plugged. But if it's anything like my truck, the line won't cooporate.

 

[j_button]

If you have ABS.. wouldn't each caliper have it's own control/distribution of pressurized brake fluid? I think each wheel gets it fluid from the abs control valve. There is two halves to the reservoir for the front and back, ensure they both have fluid in them. (There is just a partition in the tank, you fill from a common hole on top.) Just thinking out loud, I don't know but putting the idea out there.....

 

[az_max]

If you have ABS.. wouldn't each caliper have it's own control/distribution of pressurized brake fluid? I think each wheel gets it fluid from the abs control valve. There is two halves to the reservoir for the front and back, ensure they both have fluid in them. (There is just a partition in the tank, you fill from a common hole on top.) Just thinking out loud, I don't know but putting the idea out there.....

On the 90 RRC, there's one line to the rear brakes and two to each front brake. I assume both rear wheels are modulated as one.

 

[LRflip]

My ABS lines are gone with the wind...

 

[singingcamel]

Check to see if the bleeders are plugged. do your back brakes work at all ? check and see.

 

[LRflip]

There's fluid in the lines...The back brakes are NOT working. When you pump the brakes, the fluid that is at the end of the bleeder actually retracts back into the line.

 

[ptschram]

PT, I guess I didnt even realize that this is the RR tech forum but, either way Im working on my 98 DI...Is it located in the same place?

Both my front brakes bled and operate fine.

I don't have any high pressure test gauges PT! I need a bit more of a DIY fix...

No, it is directly below the maser cylinder/booster, follow the pipes.