Calling all brake experts...!

[1maniac]

I pulled a 1992 Ford Bronco out of storage to try and get it running. It has about 169,000 on the clock and the brakes didn'twork at all when I got it. She sat for about a year before I got her out. Several brake lines were completely rusted through so I replaced almost all of them. She got all new linings,calipers,wheel cylinders,hardware,rubber lines, and a new master cylinder. Flushed the system and bled it several times. Problem is that sometimes the pedal is nice and firm when stopping but sometimes she sinks to the floor gradually. Yes, I properly bench bled the m/c. TIA for any advice.

 

[labman]

You have a leak somewhere. If you don't have any puddles on the floor and a low reservoir, most likely it is inside the MC. Not sure why it would be intermittent. Still, in the modern twin piston MC, there is a lot to go wrong.

 

[TurboJim]

I would check all of your fittings for leaks. Spray on some brake cleaner and pat it dry with a paper towel. Now take a clean paper towel and wrap it around the fitting(s). Step hard on the brake. If any of your connections are not holding pressure this is one way to find them.

 

[Papa Bear]

Does the reservoir go down ??

 

[Oil stain]

It is possible that when you bench bleed the mc that you may have over extended the plunger and damaged the internal seals.

 

[labman]

In a new master cylinder, there shouldn't be anything in the bore to damage the seals. If it is bad, it should be replaced for free.

 

[mechtech2]

If it's a rebuilt MC, it could be faulty.
Especially an ElCheapo version.

 

[Gary Allan]

As labman is seeking info for ..if the mc isn't losing fluid ..there's the defective part. If you can pump it up and have good brakes ..and the pedal slowly sinks ..AND no fluid is lost ..it's the mc.

The fluid will slowly leak by ..but not fast enough to have no pedal if you pump it. Times will naturally vary.

 

[1maniac]

Thanks for all the help. I've been away from the Net for a few days but I did some checking and no leaks. The MC was from Autozone, I took it back and out in another MC. The new MC works great. Thanks I need to drive this beast now because the day I put the new MC in is the same day my neighbors girlfriend backed into the front of my 540i in my driveway and mashed the hood and front grill into oblivion.

 

[JackFish]

quote:

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Originally posted by 1maniac:
my neighbors girlfriend backed into the front of my 540i in my driveway and mashed the hood and front grill into oblivion.

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Oh man, that hurts

sorry to hear about it.

 

[Papa Bear]

Was her mc bad too ??

P.B. (I bet she felt BAD !!)