Brake pedal fade

[62MaxWedge]

Recently, I noticed while sitting at a stop, the brake pedal starting to drop while under pressure.



Okay, the master is at fault, no problem go and get a new (rebuilt one). Bleed the system at every point I could find and same problem however, if you release the pedal and re-hit it, the pedal is higher and fimer. I don't get it. WTFO?



Has anybody experienced this? and if so, what was the fix?

 

[BushWakr - RIP]

Eric,



More than one guy in here has had pretty crappy luck with reman's. However if the symptom is the same as before the change, then I'm thinking the vacuum lines need checking and the vacuum pump needs to be tested too...



Have you ruled any of those out already??



Bob.

 

[62MaxWedge]

It is not vacuum related, this much Im'sure, it is related to the hyraulics, and I'm lost. It just makes no sense to me.



After rehitting the pedal, it is real high, firm and dosen't move after the re-hit. Sounds like air however, cannot find it.

 

[Paychk]

Guarantee it is the reman, I had the same experience. The easiest way to check is go to NAPA or whoever and buy 2 plugs. One for each of the brake lines where they attach to the master cylinder, remove lines and install plugs into the MC. If you get the same symptoms the MC is at fault, if not then you know it is somewhere else in the system.



PS Did you bleed the ABS valve ?? it must come first then the rear wheel cylinders!

 

[62MaxWedge]

After advancing the pump, I did notice the idle increased however, no gages to verify or, not able to lower as the set screw is frozen.



Is it possible I'm just "over-driving" the system? I hope not!

 

[62MaxWedge]

No, never thought about that!



Will give that a bleed this weekend. If that dosn't fix the problem, will see my buddy at the dealer and just pay the $$$ for a complete new one.

 

[Paychk]

You can get brand new ones from Raybestos, Wagner, or any of the other QUALITY brake suppliers for alot less than the dealer! Any decent parts house should be able to get you a top quality one, with a little advance notice.

 

[paccool]

Eric,



You can get a new one from NAPA for around $115 plus tax. (I know Bush, I probably shouldn't post prices here but he needs to know ballpark$)

 

[BushWakr - RIP]

Hey Stan,



That's a freebee, you're not posting your products/prices/or advertising. You should be able to do it just like that bud... .



Bob

 

[BushWakr - RIP]

Eric,



You kinda thru me there... . one minute we're doing brakes and the next we're doing pump's... ... man I thought I was trippin... .



Ok, once you've tweaked the pump to the point were you are seeing noticeable idle increase, your into the 'mortality' cycle of the pump. Now, this was posted some time ago, as a result of exactly that same question. The answer means you are now "working" the pump.



As far as idle you need to do one or two things...

One, if you can, use a 10mm deep 1/4" drive socket, a short extension like the kind used for attaching sockets to a screwdriver, you know what I mean?? It's a shorty, about 1 1/2" long over all.

Next reach in and slip it over the idle screw locknut, then use an open end wrench on the little extension. You may have to move/remove the little boost tube on the side of the pump to get a shot at it.



OR.....



You can resort to using a small chisel or screwdriver, reach down from the top and line the tool up with a locknut edge, then rap it...

I have seen some tuff locknuts come loose using this method BUT.....

It really boogers' up the locknut and you'll probably never get a socket on it in the future... . that's why I like to wrestle and cuss, mumble, stick out my tongue, and give it the evil eye, then use the socket method.



Last, if you've advanced your pump timing, you should mark the current position of the pump body, at the gear cover housing, then loosen the pump and rotate it down (away from the engine top). This will give you a bit more room to work.

Then all you need to do is rotate it back up, line up the marks, tighten it, and you're good to go...



Do you know about the breakover spring settings???



Bob.