I have terrible brakes, but why

[61scout80]

any updates? noticed my booster hissing at me this morning...

 

[Ecomike]

OK, this is officially a hijack! So no apollogies. :laugh3:

I have an 87 (Wagoneer, XJ, 4x4, AW4, 4.0), that I have done extensive brake work on since 2004 (have put 43,000 miles on her since I bought it), and everything was working fine except the vacuum booster last 3-4 months. Needed to get it inspected so had to replace the Vac booster. New vac booster (rebuilt) I installed is working. I also replaced the master Cylinder, with a brand spanking new one (not rebuilt), cast iron Master Cylinder.

Now all I get, even after bleeding twice (using a one man brake bleeder kit I have used several times before with good results), is a mushy peddle (feels like standing on a bag of marsh mellows):smsoap:, down to 80% of stroke, then brakes work and peddle gets firm.

I bleed the MC first. This is about the 30th life time overhaul of a brake system I have done since 1973, so this is not my first brake job, but this one has me stumped right now. I do get a little more pressure, and higher foot peddle if I pump it 3 times, but not much more.

Any ideas folks?

 

[heyhar]

I hate to pee on your Cheerios, but two years ago, I went through three MCs-one rebuilt, two brand new, before I was happy. Best one was new from NAPA, and the cheapest of the three. Just went through it on my son's '96, same deal, NAPA item was the best of two. What we seem to find is it takes bleeding up to five times before we're happy. It's almost like there's a place for bubbles to hide. Make sure your soft lines are recent. Made a difference on both '96s, yours is a little older. Maybe dirt in the proportioning valve. Had that bite me a few years ago. You mention replacing the booster. My son's '96 pedal felt like crap, but booster passed all common tests-held vacuum for a few pumps with engine off, etc. Got one from a 'clunked' '95, 54k miles, WOW, what a difference-brakes again!
Basically, in playing with XJs for ten years, what I've found is that they make no sense sometimes. If you think something's fine, it isn't. I've worked on a lot of cars over the last forty years, and I still learn something new everytime I work on one of our XJs.
It's a Jeep thing........

 

[Ecomike]

Please elaborate on bleeding 5 times? Entire jeep 5 times, 5 pumps per wheel, 5 what, and when? Where any of your bad MCs Renix (87-90) era? Thanks.

For now I am ruling out several things like a PV problem, as everything was working perfectly but the Vac booster, and nothing has been touched but the MC and VB that were replaced. I find it hard to believe that a brand new, $100 cast iron, Renix era MC would not work as well as a used, rebuilt aluminum POS, MC, but I guess anything is possible. I just don't think it is probable, LOL.

 

[heyhar]

The most recent problems were with the '96s, so newer M/C, dual booster, but I've been through similar nonsense on my '92, old setup. Mostly we're finding the air-bubble difficulties with the rear system, and I'm finding that it takes almost two complete reservoirs-full of fluid bled to the farthest, the right rear, to bleed the farthest first. Then, probably at least half a reservoir again for the left rear. And, somehow, the left rear is where the bubbles seem most prolific. Fronts seem to be happy with the initial bleeding, rarely ever being a problem like you're having, but ya never know!
Like I said, fresh soft lines. Been stung too many times by clogged rubber, giving false pedal feel, and sometimes acting like a check valve, not letting brakes fully disengage, causing them to drag, heat up, boil fluid, expand, give high pedal, then either fail from overheating, or lock up from expanded fluid keeping them applied.

I'm getting long-winded here, but anymore when we bleed the rears, we typically use more than a quart bottle of new fluid. On the last stroke of the brake pedal, I'll just go about half-way down, have Junior close the bleeder, then I'll give it a good, hard pump, and usually feel the prop. valve click as it re-centers.Hope I've given you something to chew on!

 

[Ecomike]

Thanks, all good info, especially the 1 quart for rear brakes, I have never used more than a pint on both rears total, or a quart on an entire vehicle.

I have never once had the rubber hoses give me a problem or fail. Even after 500,000 miles. Interesting. I wonder if they last longer in hot south, coastal weather where I live? I have had, and seen stress cracking in the outside cover of them, but never once had one fail, not even on the 73 LTD I sold recently (they were still factory OEM form 1973!)

 

[heyhar]

I had an instance with a Sable my daughter had-four wheel disc. The rear soft lines are notorious for clogging shut, and acting like check valves. They jammed so bad that the caliper's piston went through the pad, the pad's backing plate, and almost all the way through the disk! All the while, the pedal felt fine! Found it by accident, just eyeballing the brakes while rotating the tires. I went on a Taurus site, and was told it is very common for their soft lines to act like this. So now I suspect them all.
At the time, they were only about ten years old, 120k or so miles.

 

[joe_peters]

Thanks, all good info, especially the 1 quart for rear brakes, I have never used more than a pint on both rears total, or a quart on an entire vehicle.

I have never once had the rubber hoses give me a problem or fail. Even after 500,000 miles. Interesting. I wonder if they last longer in hot south, coastal weather where I live? I have had, and seen stress cracking in the outside cover of them, but never once had one fail, not even on the 73 LTD I sold recently (they were still factory OEM form 1973!)

I would replace those flexible lines. At their age, and with a really good MC, they are probably going to swell quite a bit when pressure is applied.

 

[winterbeater]

A really good master cylinder and a power booster that works now! Of course, you can have someone stand hard on the brakes with the engine running (power boosting) and take a look for brake hose swelling.

 

[stephenspann27]

Thanks, all good info, especially the 1 quart for rear brakes, I have never used more than a pint on both rears total, or a quart on an entire vehicle.

I have never once had the rubber hoses give me a problem or fail. Even after 500,000 miles. Interesting. I wonder if they last longer in hot south, coastal weather where I live? I have had, and seen stress cracking in the outside cover of them, but never once had one fail, not even on the 73 LTD I sold recently (they were still factory OEM form 1973!)

Man am I going to get flamed for this.. but I wrapped my cracked front rubber lines with electrical tape The hose is made up an inner liner.. then that woven string reinforcement stuff.. then the outer jacket that you see cracking..

The hoses on my '89 parts jeep look MUCH worse.. and when I was robbing the pads and rotors form it I dropped the caliper many times to have the hose catch it..and to my amazement they never snapped...

I do plan to replace my hoses soon.. its on the list..

 

[88 Wagonman]

Man am I going to get flamed for this.. but I wrapped my cracked front rubber lines with electrical tape The hose is made up an inner liner.. then that woven string reinforcement stuff.. then the outer jacket that you see cracking..

The hoses on my '89 parts jeep look MUCH worse.. and when I was robbing the pads and rotors form it I dropped the caliper many times to have the hose catch it..and to my amazement they never snapped...

I do plan to replace my hoses soon.. its on the list..

It should be at the TOP of the list. Brakes are one place not to screw around. I would rather have bald tires than hoses like that.

 

[winterbeater]

Man am I going to get flamed for this.. but I wrapped my cracked front rubber lines with electrical tape The hose is made up an inner liner.. then that woven string reinforcement stuff.. then the outer jacket that you see cracking..

The hoses on my '89 parts jeep look MUCH worse.. and when I was robbing the pads and rotors form it I dropped the caliper many times to have the hose catch it..and to my amazement they never snapped...

I do plan to replace my hoses soon.. its on the list..

:nono: Tip on keeping everyone alive when driving an old beater. Test your brake system regularly by pushing the brake pedal down VERY hard while the vehicle is stopped. If you have a weak spot, you can blow it out and fix it under safe conditions. I did this with my sons' beater cars while they were growing up and learning about cars. Blew out a few rusted lines that way, which they learned to fix themselves.

 

[stephenspann27]

yall are scaring me talking about how crappy rebuilt MC's are considering I just installed one a few weeks ago. I really don't understand why rebuilt parts can be so inferior to "new ones." The pieces that wear.. seals.. bearings, sometimes shafts, and impellers are supposed to be replaced.. and with some parts.. like water pumps.. the only piece that isn't new is the housing.

 

[88 Wagonman]

yall are scaring me talking about how crappy rebuilt MC's are considering I just installed one a few weeks ago. I really don't understand why rebuilt parts can be so inferior to "new ones." The pieces that wear.. seals.. bearings, sometimes shafts, and impellers are supposed to be replaced.. and with some parts.. like water pumps.. the only piece that isn't new is the housing.

Many companies fix whatever part failed and never do a total rebuild. Even if they do a complete rebuild, they may not prep the surfaces properly (bores, shafts, etc.).

 

[winterbeater]

yall are scaring me talking about how crappy rebuilt MC's are considering I just installed one a few weeks ago. I really don't understand why rebuilt parts can be so inferior to "new ones." The pieces that wear.. seals.. bearings, sometimes shafts, and impellers are supposed to be replaced.. and with some parts.. like water pumps.. the only piece that isn't new is the housing.

I've used rebuilt part including MC's and power steering pumps for years (like 40 years) without problems. But the warnings are worth consideration. We used to rebuild MC's and wheel cylinders ourselves with kits (you can't get anymore) and use sandpaper on a rubber hose to hone out the cylinders. :roflmao:

 

[Ecomike]

A really good master cylinder and a power booster that works now! Of course, you can have someone stand hard on the brakes with the engine running (power boosting) and take a look for brake hose swelling.

Sounds like a swell idea.

 

[Ecomike]

I have had similar situations with the old hoses on mine. I don't think they build them like they use to.

You might try duct tape, or fiber filled packaging tape as a better choice, and top it off with self vulcanizing electrical rubber tape. Or the self vulcanizing rubber, then a fiber tape, and then top it off with the rubber.

I tried replacing one last year, and could not get one of the ends loose, so I have some brand new spares in the round too it pile, LOL.

Man am I going to get flamed for this.. but I wrapped my cracked front rubber lines with electrical tape The hose is made up an inner liner.. then that woven string reinforcement stuff.. then the outer jacket that you see cracking..

The hoses on my '89 parts jeep look MUCH worse.. and when I was robbing the pads and rotors form it I dropped the caliper many times to have the hose catch it..and to my amazement they never snapped...

I do plan to replace my hoses soon.. its on the list..

 

[Ecomike]

:nono: Tip on keeping everyone alive when driving an old beater. Test your brake system regularly by pushing the brake pedal down VERY hard while the vehicle is stopped. If you have a weak spot, you can blow it out and fix it under safe conditions. I did this with my sons' beater cars while they were growing up and learning about cars. Blew out a few rusted lines that way, which they learned to fix themselves.

What is Rust?:laugh:

 

[Ecomike]

yall are scaring me talking about how crappy rebuilt MC's are considering I just installed one a few weeks ago. I really don't understand why rebuilt parts can be so inferior to "new ones." The pieces that wear.. seals.. bearings, sometimes shafts, and impellers are supposed to be replaced.. and with some parts.. like water pumps.. the only piece that isn't new is the housing.

I have had good luck with some rebuilt stuff, like starters, alternators, power steering pumps, and AC compressors, but only if I got the premium rebuilt, lifetime warranty units, that used all new parts. I have had problems with aluminum MC housings lately (not anodized!), and with Al rebuilt MCs not lasting very long, or leaking out the rear into the Vac booster, and ruining the vac booster seals. I would never use a rebuilt water pump. Not worth risk, cost wise.

 

[joe_peters]

We are seeing more and more import parts that are CRAP new, why would you expect re-imported rebuilt units to be worth much?

Just my humble opinion, but I don't think any of the current re-imported rebuilds have been anywhere near anybody that can count to 11 without removing their sandals, let alone know what a micrometer is, or how to take measurements.

"Takee apart, washee pieces, replacee rubber pieces, putee back together as best you can, throw left over pieces in drum at the end of counter." Standing work orders for overseas re-builders.