1985 22R 4WD
I bought this truck non-running and have slowly been getting it going. First I dealt with the no start issue, now I am on the brakes. Previous owner said he never had issues when he was driving it, but the truck sat for a couple months or so before I bought it.

When it first got started there was no brake pedal pressure, and when rolling there would be no response when the pedal was almost floored, then it would lock up one wheel. I bled all 5 brake bleeders thoroughly, and bled the master cylinder while it was on the truck. The brakes then worked fine. I let the truck sit for a couple weeks, and the brakes were gone again, and the master cylinder reservoir was low, with no signs of leaking at the wheels or LSPV. I filled it, and bled them thoroughly again. Brakes were fine, I drove 50ish miles, and parked it. The next day, brakes are gone, master cylinder fluid reservoir level is low again.

I am suspecting the master cylinder or booster being bad, and I am leaning towards the brake master cylinder being the culprit because if it were the booster, I thought brake effort would be harder, which it is not. I am going to try to get one today for $50, bench bleed it and see what happens.

 

Cold be a flex line has gone south - but its only been 30 years.

 

Good call, I will eyeball those too.

 

I have a similar problem with my 87 4x4 w/ 22R G52 tranny. I completely rebuilt the brakes on the rear axles, new hardware both sides. I replaced the master cylinder, bled everything. I see no leaks, I have no puddles under my truck. I have pulled the front wheels and nothing is wet, no sign of a leak anywhere...

Any ideas?

grey

 

How about the rear wheels, guys?

 

That was where I started:

grey

 

A brake hose (front or rear) doesn't necessarily blow, or leave a puddle. They can seep, for lack of a better term, and the road grime etc can cover up the "evidence".

 

I got the creeper out and rolled under the truck checking the hoses. The flexible hoses are all dry, all three of them... I cannot find moist tubes. Mind you I have a small slow leak I fill the reservoir once every 5 - 6 weeks... The cylinders are all dry...

grey

 

Then I would next look at the rod from pedal to m/c. Other wise I would guess an internal booster leak.

 

Wouldn't that require brake fluid behind the master cylinder? I installed a new master cylinder, and back of old master cylinder was dry. The push rod was out of adjustment too, it was cranked all the way in tight and I mean tight. I had to take a wrench to it to extend it. When I got the truck it had no back brakes at all. I could not even lock it up on a dirt road. Part of rear axle brake rebuild included new bearings and seals. Both sides were soaked in axle oil. One side was packed in a oil sand composite I had to almost chisel off. Link to what I found when I started working on the truck: https://www.yotatech.com/forums/f116...x4-gem-286473/

 

I got you're situation mixed with the OP's situation. I will assume you have checked the other connections along the brake lines, like just after the m/c and down toward the frame.

 

Hey AbeWhat, I apologize for stealing your thread, did you find your leak? Where what was it?

grey

 

Driver's side caliper was leaking into the gunk and I could not see it. Thanks for the input, as usual. Swapped in a caliper and pads and it is good to go.