mojo4x420

Help! Any suggestions appreciated.

I've got 4cyl stock brakes. No ABS. Front calipers were replaced 2 years ago.

My brakes were slowely getting softer and softer. I replaced my rear drum cylinders and my brake master which fixed my problem for a few months. My master was leaking into the brake booster and was corroded.

Suddenly my brakes stopped working well again. I tried bleeding and they would work for a couple days. I also tightened my rear drums a couple clicks and suddenly I had more brake power, but a couple days later air in the system and now bleeding doesn't work again.

I just removed the 3 month old master and it's not leaking and re-bench bled it by taking the outputs of the master and redirecting them back into the reservoir. I thought maybe I just wasn't bleeding the master well enough, but that didn't help.

I can step hard on my brakes and they will work. If I step hard on teh brakes and then let off slightly, I can then push the pedal to the floor w/ no braking power.

So I would guess that something is wrong w/ my rears or my master isn't adjusted right. I have about 6mm of freeplay on the brake pedal which is the extent of spec.

It seems like air is getting in somewhere though. I don't see anything leaking.

thanks very much for any suggestions!

desertcamper67

This may sound like a stupid question but are you bleeding the brakes correctly? With a new master cylinder like yours you can ride the pedal all the way to the floor while a bleeder is open and you should start with the right rear, then left rear, RF, LF.

Also make sure the master cylinder res doesn't get too low that it sucks in air and cancels your previous work. Keep the weight on the vehicle esp. rear when bleeding.

Are you losing any fluid anywhere? Have you had the drums off to verify that the wheel cylinders were successfully rebuilt? Are all steel and rubber lines tightened and not leaking?

The last thing you may look for after bleeding the heck out of it would be to have someone stand on the brakes with the engine running while you inspect all the rubber brake hoses for swelling. You could have a bad hose that looks fine without any pressure inside. Have your helper pump the brakes slowly while you look closely for dostortions or leaks.

How old is your truck?

mojo4x420

No questions are stupid. It's an 89 22re 4runner.

I've never had a problem bleeding my brakes before. I use that order and finish w/ the lspv. I've gone through the FSM quite a few times and adjusted everything as I could.

I'm not losing fluid. At least not enough to notice. I've checked all the fittings for leaks and everything that is exposed is completely dry.

I'm going to take off all the wheels and drums today to see if there's any leaking that I can't see.

abecedarian

Assuming left-hand drive (US, etc.) bleed left rear, then right rear, then left front then right front, then bleed the LSPV (on top of the rear axle). But it seems you've got that down....

Are your rear adjusters working properly? They are 'automatically' adjusted, but you have to use the parking brake for them to self-adjust.
My wife uses the p-brake, but not like normal people. She comes to a stop, puts it in park (it's an automatic) then sets the brake. I've found that setting the p-brake while holding the pedal down helps adjust them, and repeatedly applying and releasing the p-brake gets it all working fine.

mojo4x420

I had replaced one of the rear cylinders a few months ago and I replaced the other one yesterday.

Maybe my drum is a little out of round? The automatic adjuster only seems to adjust so far. If I just use the auto adjuster, my rears don't fully grab when pushing the brake, but when I manually click the wheel a few extra turns, the brakes seem to do a better job and have more power.

Does that mean my master is not sending the right pressue to the rears?

Question: What's the purpose of the little screw on the brake master? There's a little screw between the two output ports. I had a hard time bleeding my master the first time until I opened this up a little, but the FSM doesn't mention it.

mojo4x420

I gave up, I tried everything I could find in the manual and this site.

I took it to a brake shop and they said they think my master is defective. I'm picking up a new one this afternoon and hopefully that solves the problem.

I asked the counter guy at the lordco parts shop and he said that the master was definitely brand new and not a reman, but I've got a new one coming in this afternoon anyways.

I still don't know about teh little screw in the side between the two output ports. What's it for? I had a hard time bench bleeding properly the first time until I opened it.

desertcamper67

Just make sure you go the whole stroke when you bench bleed it. Bottom out the plunger. When you get nothing but fluid you are done.

mojo4x420

I traded my old master for an identical new one. My brakes have never felt so good!

On the new master, the small side bolt between the ports has a paint mark so you can tell if it's been adjusted.

My original master wouldn't flow out the rear port until I opened and closed that bolt. I need to take it apart to see what's happening in there, but I guess I wasn't supposed to touch that bolt.

They both were beck arnely brand. About 1/3 the price I could get a toyota master for.