FJ60 Brake Problem - bleeding master (1 Viewer)

[woytovich]

I just installed new (rebuilt) calipers in the front with new custom (hydraulic shop) soft lines to the calipers (these are fairly long to facilitate taking off the calipers to service the knuckles in the future).

Now I'm bleeding the system. Fresh fluid, speed bleeders at all 4 corners. Started with passenger rear, then driver rear, then pass front then driver front.
It was difficult to get bubble-free on both sides of the front...

Now my problem is the pedal feels firm to the place where it stops then slowly it moves farther down as I hold pressure. There are no visible leaks.

Air in the system still? Bad brake master or booster? Vacuum leak?

HELP!

mark

 

[LAMBCRUSHER]

my experience with lines being open for longer than it takes to eat half a sandwich is that bleeding is a draaag. short of that, I'd have to consider the master...try bleeding a couple pints thru the fronts. I have always gravity bled with decent results. I tried speed bleeders a while back and they didn't seem to work at all altho I can't remember why. I just decided that gravity works and it continues to do so...if there is any chance that enough fluid left the system to get air in the master, you might start by bench bleeding the master, then loosen the lines on the prop valve and let it gravity bleed, then loosen the lines to the calipers and let them gravity bleed, then open the bleeders on the calipers and let them bleed...ih8brakes...

 

[Output Shaft]

Assuming that the brake pedal was firm before the caliper & hose-to-caliper upgrade, the master cylinder & booster would not have changed for the worse.

Since you mentioned that it was difficult to get the fronts bubble free, that's pointing to air not getting purged completely.
The speed bleeders only work properly if their thread sealing compound is still sealing well (I use them too). Once they've been cracked open a few times to bleed & test & bleed, the thread sealant breaks down & air can get sucked back into the caliper through the threads with every upstroke just like any other normal bleed screw - completely negating to whole purpose of them.

I think they are only good for a few loosen/tighten cycles before they have to be removed, cleaned off completely, & new thread sealant applied to the threads (available from Speed Bleeder).

I think there's still air in the system.

 

[jonheld]

Remove the bleeders and put a thin coat of grease on the threads. This will keep the air from leaking past and giving you "false bubbles". I just went through this last week on the LX450. I don't use speed bleeders anymore.

 

[doug720]

I had this same problem, and it turned out to be a bad master cylinder. Doing a brake service, I could not get it bleed. I tried and tried.

I think what happens is when bleeding, especially when the master cylinder is old, is the pistons are pushed past there normal operation range. This allows "Crud" to to damage the o-rings, or cause them to not seal very well.

I had my 60's master go bad recently - it looked like the stock 1985 master! It showed the similar symptoms - solid pedal, but if held, it very slowly bleed down. It also would go down part way if s light pressure was applied, then firm up with a single pump. New master fixed all issues.

I took the old master cylinder apart and could not believe how much crud was inside!

 

[FJ60Seth]

1. I too have stopped using speed bleeders. I use a jam jar partially filled with with brake fluid and a piece of hose.
2. Do the "longer hoses" have a low point where air can become trapped?
3 Are the calipers installed so the bleed screw is at the top?

 

[woytovich]

FWIW the rears bled bubble-free pretty easily.

Bleed fittings at top.

The longer hoses normally DO have a loop that is up higher than the bleeder. After having problems I looped them down so they were all below the bleeder (this results in a "M"" shaped hose with two high points, but both below the bleeder)

The Speed Bleeders are new, with their sealant intact.

I will try again with a combo of the Speed Bleeders and a 1/2 full jar of fluid.

If that fails I may be trying to get a new master tomorrow!

mark

 

[60Works]

I've had 2 masters that behaved the same way. Both were new Aisin. Bench bleeding helped but didn't solve the pedal sink. I got so frustrated trying to bleed I gave up and let the truck sit for a couple of weeks until I had the patience to work on it. It functioned perfectly when I returned.

Gravity bleeding works if you have the time. If you feel it's safe, drive it. Or let it set for a few days.

BTW - the driver's side bleeders are farther from the master so should go before the passenger's side.

 

[woytovich]

I am headed to Moab and really would like excellent brakes for that wheeling.

I am going to replace the master and try again.

 

[Spike Strip]

You've got air trapped in the system somewhere. Tap each caliper / wheel cylinder / MC with a mallet and try the bleeding again. Best if you can have someone bleed while you tap at each corner. Also have that someone put pressure on the pedal before opening the bleeder.

I had this issue also when I redid the brakes with 4R stuff - took two days to get a firm pedal. Didn't make the wife feel very amorous, you know what I mean, since she had to be the pedal pusher.

You could also buy / rent a pressure bleeder.

 

[81Red60]

I had the same issue as you. I put at least one bottle of brake fluid through the system and still had a spongy pedal. I finally put a brand new master on since that was literally the last part I had not replaced new. Apparently my master had a leak or air hole somewhere that kept me from getting a good deal on the system. Once I replaced that it was like a brand new car.

 

[John McVicker]

I will repeat what others have said...gravity bleeding will most likely solve your issue.

 

[woytovich]

I'm in a crappy place... I replaced the master and bled the system. I am not happy with the result, speed bleeders are not offering a high level of confidence... and I am working alone. Tomorrow I MAY have the option for a bit of help to do a "standard" bleed.

At the moment the pedal has resistance but does not feel like it should (Although I have not driven the 60 since last fall and the brakes on my daily driver 2003 Yukon XL are not the things to be comparing to) The pedal feels like it keeps moving to a point too low in the pedal travel, it does have resistance although the first push has very little resistance.

I can't drive the truck on the road yet because I am waiting in replacement U bolts for the rear springs.

I feel like a total knucklehead at the moment and may even resort to taking it to my "old school friendly" mechanic to have him fix it... (yikes!)

Arrrrggghhh....

 

[LAMBCRUSHER]

Put the stock bleeders back in and gravity bleed it. You may need to get the help and do a pressure bleed but gravity does work and works while you're alone. You do not have to push the pedal for it to work btw, just open it up, go grab A beer and nurse the reservoir and don't let it pull in air.

 

[Cruiserdrew]

The sinking pedal sounds like a bad master. Spongy brakes are usually air. Me, personally, I like speedbleeders. I get the system all bled, then call my wife and she pumps the brakes a couple times like real brake bleeding and all good. She won't tolerate 30 minutes of brake bleeding but 5 minutes is OK.

On a 60, if the rear brakes are not adjusted well, it makes it very hard to adequately bleed the brakes. You need a Cruiser friend there to pump up the brakes then quickly bleed.

Since you're in rust country, do the rear bellcranks work to keep the brakes adjusted? This is sort of critical for rear brake function.

But I agree, in Moab with it's steeps, you need really good, confident brakes.

 

[LAMBCRUSHER]

he said he replaced the master...

did you bench bleed the master?

 

[woytovich]

I made sure the res remained full and fluid was running out of the ports as I screwed in the lines. What is the proper way to do that?

 

[woytovich]

I have used the power of the interwebs to see some bench bleed info but I'd like to hear about a method that is maybe more cruiser specific if such a thing is possible.

Funny that i I had no problems whatsoever when I reassembled my 40 and bled those brakes...

 

[OGBeno]

Keep bleeding.

 

[doug720]

Bench bleeding a master is the same for all vehicles, with the exception of some ABS equipped models.

For an LC, you need a way to make a closed loop from the line ports into the reservoir. The way this is typically done is using short pieces of brake line screwed into the MC ports with stubs bent to fit into the reservoir below the fluid level. Fill the MC w fluid, and push the piston rod in until you see no more bubbles. Disconnect the bleeder lines and install the MC, then bleed the system as usual.

Hope this helps.