Brake line troubleshoot

[Brimful of FJ]

Hello wise ones, I need guidance. If you can't tell me the issue, then a systematic approach to troubleshooting would be great, thank you.

I recently bought my FJ45 and let's just say the brakes are a conversation piece. In general, the maintenance of this vehicle was not been upheld or done with much interest by the previous owner. The brake fluid was black, which gives you an idea.

Driving it, the brakes were completely spongy and felt like they were just full of air. Also, when braking, the vehicle would veer to the right so strongly you would need to start turning left as soon as you were pressing the brake pedal. After driving for 20 mins (which I was doing safely on empty roads to get an idea of all the issues), the front brake started smoking and letting off a burnt smell. I think this may have been a stuck brake caliper, as a guess.

Today, I did the brake fluid, which I know how to do, so there's no fear of operator error. But the brakes all have air coming through the lines to no end. I literally flushed the first one about 6 or 7 times. The fluid was clean after the first flush, but the bubbles never went away. They weren't small bubbles either, it was mostly air coming up through the line. I thought maybe there was air sneaking into the line from under the nipples when I loosened them to extract the fluid, because there was a bit of play in them when slightly unscrewed, but can that play be normal? It didn't make difference if I did with them tighter anyway. And there are no fluid leaks from the nipples or anywhere along the lines. Also, practically no fluid at all came out of the front left, which must have something to do with the vehicle veering right when braking.

After doing all this, the brakes still behave exactly the same when driving. I will be taking them apart to inspect everything in the next week or two, but I thought it would be worth seeking advice now because I imagine the air issue won't be related to the brake drums.

Also, I removed the tubing going between the brake booster and air intake manifold as I wanted to dip inside the brake booster to check for leaks. The good news is there is nothing leaking into the brake booster, the great news is that I can't get that bloody tube back into it. Is there a trick?

Thanks for any help given.

 

[MDH33]

First thing I would do is make some bench bleed lines and test your mc on the truck. You'll be able to quickly see if the MC is bad and pumping air into the system.

 

[Mr. Green]

You have a combo of problems. Likely corroded piston on the side that is dragging (assuming drums all around) plus fully seized on the opposite side hence the counter steer. I had this as well for years so made the plunge into 4 wheel disc. Bench bleeding master is a good start then move to furthest away brake. Work back to closest. Air in lines is the squishy pedal… if you use a clean container now that you’ve changed the fluid you can reuse it if doing the one man tube trick. Tube into bottle but partial closed or cracked open bleeder. They work great once bled and adjusted but can be a pain to get back to good.

 

[Brimful of FJ]

Thanks, I'll start looking up how to do this now.

 

[Brimful of FJ]

First thing I would do is make some bench bleed lines and test your mc on the truck. You'll be able to quickly see if the MC is bad and pumping air into the system.

Thanks, I'll start looking up how to get this done now.

 

[Brimful of FJ]

You have a combo of problems. Likely corroded piston on the side that is dragging (assuming drums all around) plus fully seized on the opposite side hence the counter steer. I had this as well for years so made the plunge into 4 wheel disc. Bench bleeding master is a good start then move to furthest away brake. Work back to closest. Air in lines is the squishy pedal… if you use a clean container now that you’ve changed the fluid you can reuse it if doing the one man tube trick. Tube into bottle but partial closed or cracked open bleeder. They work great once bled and adjusted but can be a pain to get back to good.

Hello, it has been a while as life has gotten in the way, but I'm back in the game. I got a kit to bleed the master cylinder and it looked fine, it's also new so I doubt the internal parts have any damage. Booster also new. But the brakes are still full of air that won't bleed out.
- Again, I can't see any damage or leaks to brake lines.
- The brake is spongy even when the car is turned off.
- The booster hose is old but still has good suction.
- There is no real difference in the brake pedal when the car is on or off.

My next plan is to remove the drums to check everything there, I suspect brake cylinders, but if anyone has any further advice to this point it would be appreciated. Thank you.

 

[MDH33]

Have you adjusted the wheel cylinders? Might be too loose. Whenever I bleed drums I tighten all the wheel cylinders until the shoes are making contact with the drums, then bleed, then back off the adjusters a few clicks until they just barely make contact. Doing it this way ensures you get good pressure in the system to force the air out and also gets all the cylinders adjusted in the process.

 

[Mr. Green]

Above is correct. If you can continue to pump brakes to firm up pedal then you have too much adjustment in the wheel pistons.
If pumping and it is still squishy it’s got to be air or master. Simple hydraulics.

 

[70fj40]

Good advice above. I would also suggest replacing all your wheel cylinders before trying to bleed anymore. They need replacing/ rebuilding anyway.

 

[Brimful of FJ]

Looking at the left front and rear brakes, it seems likely the cylinders are the issue. There is almost no movement on the left rear and no movement at all on the front left when brake pedal is pushed. The front left brake was pushing out against the drum , which is why it overheated during driving, but probably not extremely hard, which would explain the veering to the right when breaking. They are very dirty, which goes along with the previous owner's lack of maintenance. The rear brake photo is after a little clean, front is when I got the drum off.
I will replace the cylinders all over. I have the part number for the rear cylinder, 47550-60120, but I can't find the number for the front. Can anyone let me know?
There is also some pitting on a brake disc pictured below, is it enough to need replacing or is it ok?
I will order the parts asap and let you know how it turns out.
Also, I realise now that I could have adjusted the cylinder from the rear to make my life easier, but I came up with a technique of pulling the drum off which I gave a photo of below. I'm not sure if this is a common thing or if I've discovered something.

 

[Malleus]

Replace that brake shoe; it's too old. Brake components are safety items; don't cheap out on saving your life. Or someone else's life.

I've seen claw hammers used for far worse tasks. Like installing U-joints.

 

[Mr. Green]

FWIW I was able to rescue wheel cylinders back 20 years ago by c clamp across the working cylinders and pump braks to break free the stuck ones. Once free, I cleaned them up on wires wheel and put new seals on. Worked great for another 15 years but they eventually did the same thing you’re fighting now as I didn’t drive it enough to keep them corrosion free. Good luck with the cleanup work.

 

[Skreddy]

If the master cylinder and booster are new: was the booster to master pushrod depth properly set? It needs to be checked and set, not just “factory”.

And also a general brake and cylinder job, as stated.

 

[DSRTRDR]

the best way to get air out of the brake system is the "two-person" method

@Pin_Head has often commented on that here in the 40 forum - seek out his threads

 

[DangerNoodle]

I would also check your pedal adjustment if you still feel like the brakes are dragging at all times. I've seen plenty of those misadjusted just enough the problem starts to show after a while of driving.

I've also had a few bad master cylinders new out of the box from parts stores, so if the problem still exists after all the adjustments and replacements, it may be worth replacing again. Don't forget to set the depth on the pushrod as stated before.

4 corner drums are notoriously hard to bleed well, especially if you have two wheel cylinders. Basically impossible to fully bleed without two people. I would recomend a friend, a child that can reach the pedals, or a well trained dog to help with that.