1984 Runner Brake Troubles

[04 Rocko Taco]

1984 4Runner, 22R, 5 speed.

Extended Stainless Steel TG Brake lines.

I recently installed the extended brake lines, and bled the brakes, they obviously needed bleeding BEFORE I installed the lines, becuase for my lfie with the rig, the pedal has always been soft, and travel is pretty far before it gets a solid feel, I bled the brakes (rear pass, rear driver, front pass, front driver, LSPV, then round 2, rear pass, rear driver, front pass, front driver, LSPV -- in that order) the pedal was SOLID. only about an inch of travel before it was good and solid feel. I loved it, best stopping in the runner since I've had it. Fast forward a week to today. Pedal is squishy again, travels almost as far as before before the pedal gets hard. I keep checking the resevoir, doesnt seem to be leaking fluid, or if it is, very small amount, and I see no evidence of a leak anywhere, not at any of my new joints with the SS lines, not at any loose bleeder screws, not at the master, no puddles in the wheels from the calipers, only thin I hvent checked is rear wheel cylinders, but, like I said, dont seem to be losing much fluid...

Any other ideas?

Possible bad master cylinder?
bad booster?

[Tankota]

Thats strange. I guess you could do a quick bleed round and see if your gettng air in there somewhere. If there is air in the system, then you have a leak.

A bad booster would result in very hard pedal, I've had that before.

If you stand on the brakes hard, does the pedal bleed down, possible internal MC leakage.

[04 Rocko Taco]

Doesn't seem to, pressure seems to be consistent, no matter how long/hard you are on the brakes, its just drastically softer than a week and a half ago... this is what has me miffed. how can you lose pedal feel with no leak?

What else have you got? I'm going to bleed them again tonite, see if I can get the pedal to firm up again.

Also, If I wanted to check good for a leak, and say, hold the brakes down HARD for an hour or so (jam the pedal down with a peice of tubing) should the truck be running so that it is utilizing the booster, or just as good with the truck off? What do we think guys?

[Intrepidyota]

If you hit it once and it is low, will it come up some if you hit it again? Try this, it will only take a minute, pop the small cover off the inside of the backing plate on the drums in the rear, grab a screwdriver or brake spoon and turn the adjuster until the brakes are snug in the back, then drive it and see if it does the same thing again. My truck does that, I think it is the adjusters on the rear brakes, they seem to un-adjust after a little while and they don't re-adjust...ever. I can go back there snug it up, get good braking for an hour of use, then slowly it goes away until I have little or no pedal on my first pump. I haven't fixed it yet, it is on the list of maintenance items I have to do once I finish all my current mods.

[04 Rocko Taco]

my shoes are just about GONE, so thats on the list for this weekend hopefully. Maybe once they are redone, and working good, the whole issue will come together, and get fixed.

[corax]

while you have the rear drums apart, pull the rubber boot back on the wheel cylinders. if anything drips out, replace the wheel cylinder. Even though it may not be leaking much, it may be allowing air in to the system

[04 Rocko Taco]

I plan on replacing the cylinders anyway, I figure these came on the truck in 1984, so replacements couldn't hurt. lol

[yotastan]

I had a similar problem after I replaced the master in my 85 runner the pedal felt great for a week or so and then it went squishy and I traced it back to my wheel cylinders… as corax said it might not be leaking much but just enough and it fixed mine up pretty good.

Good luck man

[Edit - Good Times - Spell Check]
Edit Rocko: Spell Checked Lance's Spell Check

[4runnerchevy]

Hey Rocko, my LSPV went out which prompted me to get rid of it. In the LSPV the excess pressure from the rear returns to the front depending on your load. I think the seals on the inside go bad after 20 or so years. I also run disks in rear and wanted a little more control over my proportion. I used a Summit prop. valve and a few adapters.

[Tankota]

I had a simular problem after i replaced the master in my 85 runner the pedal felt great for a week or so and then it went squishy and i traced it back to my wheel cylinders..as corax said it might not be leaking much but just enough and it fixed mine up pretty good,
good luck man

[Edit - Good Times - Spell Check]

GoodTimes' spell check doesnt seem to be working