helikyler

Hi all... I've got a couple years of frustration with my 1986 4Runner brakes and I'm trying desperately to solve this. I'll try to be brief but thorough:

Starting 2 years ago I was having my brakes need to be pumped to get sufficient braking (like 2-3 pumps consistently, braking worked good then). The condition never really worsened, just got used to pumping my brakes. When pressure is pumped up, it stays (no leaks, but takes pumping).

Things I over last 2 years:

1. 2 years ago, replaced master cylinder, did bench bleed and 4-wheel bleed. Did not help, problem stayed.
   
   I got in an accident about a month ago as a result and have reopened the case to finally try and solve it.

Things I have done in the last month:

1. Replaced both front calipers & shoes
2. Replaced springs and star adjusters in rear drums (pre-adjusted to approximate place there were and did foot adjusting while rolling in reverse but have not manually adjusted stars from back of drum)
3. Replaced rear wheel cylinders
4. Brake shoes were 80-90% life so I didn't replace them
5. Bled whole system (Driver rear, Pass rear, Pass front, Driver Front, LSPV aka LSPBV)
6. REPLACED MASTER CYLINDER AGAIN with "new" rebuilt unit from Auto Zone since nothing else helped... and STILL SAME PROBLEMS!

CURRENT CONDITION:

• System has clean, new brake fluid in it from all the flushes
• New (rebuilt) Cardone/BrakeBest calipers and NAPA pads
• Rebuilt drums via Cardone rebuild kit
• Has inconsistent braking reliability now, I have had my brakes go out almost entirely
• I still always have to pump like before to stop unless just done
• Sometimes when returning to my 4Runner, before starting engine, brake pedal is pressurized rock hard
• Booster seems to be working because upon starting truck the pedal softens and goes toward floor and braking (after pumping) seems booster-assisted and not hard
• Parking brake is way out of adjustment - pulled the way out I still don't have any parking friction, worked well before recent work though

QUESTIONS:

1. Should I be suspecting the load sensing proportioning valve (LSPV) if I was able to bleed all 5 points? A friend has suggested blocking the return line from LSPV to see if braking pressure is restored. Good idea?
2. Could my booster have anything to do with this?
3. I know I need to go out and spin my rear wheels and adjust my drum brakes down more, but shouldn't I still at least be getting plenty of consistent braking from the front brakes?
4. What else could it be???

Any help or guidance would be greatly appreciated!

Gevo

Wow. You should not drive it around until you get it fixed. It could let go completely and you will be in much worse sotuation.

Ok. I have not done any work onmy breaks on this car yet.. but some thi gs come to mind. Did you run into any isssues when bleeding the lines? Such as.. was the fluid coming out all 4 points in normal quantities?

Also add the details of which breaking system you have. Im curious about this so id like to look at the correct fsm diagram.

wyoming9

iTrader: (1)

The rear brake shoes need to be adjusted up and the emergency brake keeps them adjusted. ** Toyota Brakes are adjusted by the use of the emergency brake what your trying does nothing

Also some place your drawing air into the system the leak of fluid can be so small as to be noticed.

I have never bled a LSPV my attempt was so very expense

Do you need to add brake fluid at all??

Not replacing old rubber brake hoses can also cause brake performance to drop off as the hoses balloon up

I am curious just how one rebuilds Brake drums??

sphealy

iTrader: (1)

Big question. Is there fluid loss. If your having to add fluid it's going somewhere and that is the place to start. The e brake is all cable actuated and should have no issues as long as cable is intact and pulling on brake shoes assuming brake shoes are properly adjusted.

FGZ

Have you upgraded anything? All the pumps that lead up to a firm and holding brake pedal just sounds like the MC being too small for the calipers. But if the booster hasn't been tested, that is where I would look since everything else sounds fairly checked out.

And about the LSPV - unbolt the arm and tie it up as high as possible to see if it makes a difference.

helikyler

Thank you all!

@Gevo: I did not have any trouble bleeding all four wheel locations and the LSPV, so I did not suspect any issue with the LSPV (usually not being able to bleed the rear wheels happens when it fails). I am on a stock brake system for the 1986 4Runner DLX as far as I know.

@wyoming9: Bleeding the LSPV is easy... it bleeds just like the other locations do, it just needs to be done last. It's above the rear diff and has a normal bleeder valve. What I meant by "rebuild" was I got a kit for both rear wheels and replaced the springs, pins, one of the levers, both wheel cylinders, etc. To me that's kinda like replacing the calipers and pads on the front so I called it a "rebuild". I did not replace any hoses but there are no rubber hoses and I have not seen any bulging or leaking.

@sphealy: No fluid loss, thankfully.

@FGZ: totally stock system. But I will try what you said about the arm! I have heard someone else recommend something like that. If I have issues still that's where I'll go next.

UPDATE: Yesterday I went and manually adjusted the star adjusters. Per the Chilton manuals I have, I tightened it until I couldn't turn the wheels with my hands, occasionally tapping the brakes to center the brake shoes. Then you're supposed to back off about 5 notches and check that the wheels can spin with no drag or just barely any.

USEFUL TIP Do NOT tighten them this much unless you can see the detent lever through the adjustment hole OR you have the brake drum OFF while you do it. It's actually hard to "back off" any notches since you're not really supposed to be able to do that without another screwdriver or tool to push the lever away from the star adjuster to release it for "backstabbing".

I was able to back off the adjuster on the first wheel that I tightened but after that experience I just tightened the other wheel until I had a slight drag.

The brakes are working good now! My theory at this point is that the rear brakes were so far out of adjustment that without clamping pressure in the rear to let pressure run to the front brakes, the front brakes weren't getting much pressure at all.

Now that the rear brakes are adjusted up, my braking is good (not amazing, but better) AND the parking brake works - even to stop the truck in a slow roll.

Next I'm going to bleed the system one more time with my neighbors vacuum bleeder and then adjust the brake pedal since I still feel like the braking begins lower than I'd like.

Still welcoming any feedback from you guys! Thanks for all the fast replies.

wyoming9

iTrader: (1)

Well being you live in California You have no idea what the great salt belt trucks are like.

It is not the physical act of bleeding the lspv but everything rusted solid .

The one only I ever attempted to bleed the bleeder was rusted so bad even with cleaning no way was a socket going to fit.

Till it was all finished Brand New LSPV and hardware and brake lines quite $$$ so I now leave them alone or remove them.