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Discussion Starter · #1 · (Edited)
Hey yall. Need some help. I dont have an Impala(I wish) but a 90 Brougham(Very simular to the box caprice with the TBI 350 w/ABS) and I have no rear brakes. Started when my rear hard line rusted halfway back. Replaced it and now have no fluid to the rear brakes. I put on a new MC because it was leaking anyway and bench bled it first, still nothing. Another combo valve, nothing. A brake shop, nothing. I can see the valve in the combo valve is sitting in the right spot and I have no brake light when its plugged in. I tried searching the forum first but came up empty-handed. Any suggestions
 

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Is the pedal holding pressure? I would hold pressure on the pedal and try loosening the line at the MC..rear brake is the front line, and see if it is pushing any fluid there, if so I would start looking at the main line going back for a blockage....unless both wheel cyclinders a frozen. A brake shop couldn't figure this out?
 

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90 Brougham(Very simular to the box caprice with the TBI 350 w/ABS) and I have no rear brakes.
Drum rears, yes?

Started when my rear hard line rusted halfway back. Replaced it and now have no fluid to the rear brakes.
Brake fluid does 2 things; enables the hydraulic capability to allow the various brake components to stop the car and prevents oxidation from attacking those same components. Where you have no fluid, you have oxidation. This could be substantial enough to prevent those components from working properly or at all. You may very well have to keep replacing line, both soft and hard and particularly the "5th line" atop the axle. I'm assuming this is the setup on your car since it's a 90. Then replace the wheel cylinders, again assuming that it has rear drums.

I put on a new MC because it was leaking anyway and bench bled it first, still nothing. Another combo valve, nothing. A brake shop, nothing.
And you probably won't until the above mentioned are addressed. What I'm most curious about is this brake shop. What do you mean? They couldn't find anything or make any recommendations? At all? That's pretty pizzpoor sorry.

You could try just replacing the wheel cylinders and 5th line, which I suspect is at the core of this, but I'm afraid there may be rust/debris inside the lines that could become problematic for you down the road.

I'm envisioning your original hard line rusting through to the point that you had "soft, spongy" brakes (which many people live and drive w/ all the time) which still "worked", but which also sent deposits of rust on back until they collected enough to form a "clogged artery" at some point prior to the 5th line. If it had been only one side, the blockage would have been beyond the 5th line on one side or the other.
 

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Discussion Starter · #4 ·
It has rear drums. The brake shop said they think the combo valve is stuck so I got a used one with the same results. With the valve off, I took a compressor and got the valve to move back and forth with ease so I positioned it in the right spot and put it on. Got no fluid past it still. Then I took out a spring in the valve(had something to do with the rear line) and got fluid so I Tried bleeding again, nothing. I can get a tiny amount of fluid to the back but it only fills up about an inch of the bleeding hose, the rest is air bubbles. I'm 95% sure I have no leaks in the system and I have replaced the T fitting and both lines going to the cyls. I think I have tried everything with these brakes. Another thing...I have been trying to fix this for two years. I put a new motor in last year and have only drove it maybe, now that I think about it, 500 miles because its only using front brakes.
 

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It has rear drums. The brake shop said they think the combo valve is stuck so I got a used one with the same results. With the valve off, I took a compressor and got the valve to move back and forth with ease so I positioned it in the right spot and put it on.
The valve wasn't the issue. If they claimed it was the valve, wasn't actually the valve and could offer no other reasonable suggestions, I wouldn't frequent the shop again.

Then I took out a spring in the valve(had something to do with the rear line) and got fluid so I Tried bleeding again, nothing.
Um, be careful here w/ the percentages of braking being applied to the front and rear. The proportioning vavlve is setup to deliver something on the order of 80% front and 20% rear. You don't want to remove anything which will alter this.

I can get a tiny amount of fluid to the back but it only fills up about an inch of the bleeding hose, the rest is air bubbles. I'm 95% sure I have no leaks in the system and I have replaced the T fitting and both lines going to the cyls.
To be clear, you've replaced the rear hard line from MC to "T" fitting, the actual "T" fitting, both hard lines from "T" fitting to soft lines, both rear soft lines and both wheel cylinders? If the answer to any of this is "no", then replace whatever was missed. I'm as sure as I can be over the internet that you haven't any leaks either, however I am concerned that if rust/debris was still in a portion of the rear brake assembly you didn't replce, that rust/debris will still migrate back and could compromise some of the components you've recently replaced. To sum up, in this particular case you want to replace EVERYTHING that contains brake fluid from the rear hard line on back. The blockage could be anywhere and Murphy's law states that the part you may have omitted will be that place.

I think I have tried everything with these brakes.
Still working on determining this. Patience and complete respnses will get us there...cwm1
 

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Discussion Starter · #6 ·
Thanks SEO9C1 and Gregg, been very helpful. The rear brake system routing goes...from MC to combo valve, valve to ABS unit, ABS to rear T fitting, fitting to cyls.

I replaced ABS to T-fitting, T-fitting, T-fitting to cyls. Not the cyls. This one doesnt have soft lines. If there is a blockage, would I be getting the little fluid I'm getting? Also wondering about the ABS unit having air.
 

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Discussion Starter · #7 ·
So I got it figured out. The combo valve was the problem. Last week, I ordered a wilwood combo valve, today I put it on and I got fluid everywhere. I was able to get everything bled correctly. Thanks for the help.
 
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