01 montero limited brake question

[Mozo]

Yep..had my wife push the pedal while i opened it all the way and nothing..she wasnt pumping with force but its my understanding the hbb pushes the rear system with the pedal depressed. Should i get in and put physical ft pounds on the pedal?

 

[Salonika]

I’m not familiar with an HBB system but I do know that on non-HBB systems (vacuum based) you can at least bleed them with basic foot pressure on the pedal. If the vacuum assist fails you still have brakes they’re just super inefficient and hard to use. I’d imagine HBB is the same idea, it’s an assist system. The basic hydraulic function of the brakes should still function without it.

Can you get the front calipers to bleed by applying pedal pressure and burping the bleeder screw? Does your vehicle have a proportioning valve for the rear brakes?

 

[Mozo]

I was told the rear brakes are more or less fly by wire. The fronts are bled as normal with pump off but the rears are done with the pump on.

 

[plh]

I was told the rear brakes are more or less fly by wire. The fronts are bled as normal with pump off but the rears are done with the pump on.

I have not read back in this thread, but have you reviewed the FSM procedure for brake bleeding?

 

[Michael Brown]

Grab a Gen 3 FSM from the link in my signature and check section 35A for the brake bleeding procedure.

 

[offthepath]

I rebuilt the rear calipers on my gen 3 and did not do anything special to bleed the brakes.

The guy said the problem started while he was working on the rear calipers. Have you verified the caliper works and the piston is not binding? Is fluid getting to the caliper?

 

[Mozo]

I have not checked the calipers yet. I guess i should pull the brake line off and see if fluid is getting back to them. Ive read somewhere that you are supposed to bleed the caliper as you clamp it open as opposed to forcing fluid back up the line. Is there a valve between the front and back that could be damaged by pressure back against it?

 

[Salonika]

I have not checked the calipers yet. I guess i should pull the brake line off and see if fluid is getting back to them. Ive read somewhere that you are supposed to bleed the caliper as you clamp it open as opposed to forcing fluid back up the line. Is there a valve between the front and back that could be damaged by pressure back against it?

I’ve never heard of this.....the only time clamping can cause damage is if your rear caliper has the e-brake built in to it, in which case you are supposed to use a tool to screw the piston back into the caliper. You can still use a clamp though just a tiny bit to help get the caliper off the rotor, but only clamp the bare minimum to accomplish that. Once the caliper is off, if you are putting new pads on, you would then use the tool to screw the piston back in, put new pads in, then put it back on the rotor.

My truck has the drum style e-brake on the rear (the rotor does double duty and has a drum part of it for the e-brake and then the disc for the caliper as well) so this isn’t a concern for me, not sure about the Gen-3 though. Both of my cars though have the e-brake built into the same caliper as is used for normal braking. If your Montero doesn’t have this style, I am not aware of any damage that could be caused to any part of your braking system by clamping & pressing the piston back into the caliper.
But even if your piston was locked up for some reason, you should still be able to get fluid to purge out of the bleeder since the piston doesn’t need to move for that. Keep us posted. Even an ABS system allows fluid to move in both directions....

 

[coffeegoat]

I can confirm the Gen 3 (at least 2001) have the dual duty rear drum/disks. The reason that I have heard you should bleed the brakes (rather than compressing them) is that the fluid nearest the brakes it the most contaminated/heat damaged, and it's desirable to replace it rather than just push it back into the system.

 

[Mozo]

I cant understand why no fluid came out when i tried bleeding the rear. Unfortunately it is snowing here today and i cant try to work on the truck. Hopefully tomorrow or Thursday...thanks for the info and suggestions.

 

[Salonika]

I cant understand why no fluid came out when i tried bleeding the rear. Unfortunately it is snowing here today and i cant try to work on the truck. Hopefully tomorrow or Thursday...thanks for the info and suggestions.

Unless the lines to the rear were empty of fluid, might take some pumping to get fluid back there.....

 

[corprin]

Unless the lines to the rear were empty of fluid, might take some pumping to get fluid back there.....

Exactly my point on day one of this. The lines were likely drained out and he replaced the HBB. This needs prime and bleeding before the rear lines see a drop of fluid.

 

[offthepath]

Have you used a vacuum bleeder or standard pump, etc method?

 

[Mozo]

I dont know why or how the rear system would be void of fluid...i replaced the hbb and it ran to pressurize the system..yet i cant feel any assist to the brakes which are only actuating up front..no air or fluid or any pressure escaped from the bleed nipple on the rear calipers..something is amiss...physically or computer projected or gremlins?

 

[offthepath]

If you haven't already, use a vacuum bleeder. IMHO its a necessity after purging all the fluid. If your trying the normal way, I'm sure you have an air bubble in the line.

Not sure how it would work with hbb, but I've had vehicles/motorcycles with brakes that refused to bleed and I've had success gravity bleeding (ie leave the bleed screws open still fluid runs out). May be worth a try.
I've also had stuff where I needed to reverse bleed the system using a syringe to push fluid through the bleed screw.