Question about 1983 Cadillac Eldorado

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Brakes get hard and no vacuum from motor

The brakes get hard while driving,I will pull overand pull booster vacuum! So I turn off car and wait a few mins,then when I restart car I have vacuum and brakes are normal.i replaced old vacuum pump that was tapping with another one that was bad because it free spun and did not suck or blow out the tubes.i put mine back one and this is what is the vacuum pump going bad? Is their another part that could cause these issues that I am missing? Thanks for any help.

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  • Kristi Cantor May 10, 2013

    I vacuum tested all the lines and replaced any that did not hold.also tested modulator on trans and egr. I put my finger over i bottom vacuum hole on pump and turned the wheel it moved around with pressure from one hand,does this mean the diagram is weak? Could iit not be holding enough vacuum? Is that how you test these pumps?

  •  Stephen
    Stephen May 10, 2013

    There should be a check valve on the power brake booster. That valve is supposed to "hold" vac inside the booster. The pump only produces vac while it is running. The hose between the pump and the booster could be damaged inside and blocking the vac at times. Rare but it does happen. I would probably rig up a gauge in the line going to the brake booster and check to see if vac is present when the engine is running. The booster could be leaking.


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The pump boosts engine vac so yes it could be a failing pump.
You could also have a hose that is collapsing inside.

Posted on May 10, 2013

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The brake booster is not the problem. The Master cylinder will need to be bench bled before bleeding the braking system.

Posted on Mar 26, 2009

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SOURCE: '97 SLS - brake lights don't turn off when i release the brake.

I would definitely go after the brake light switch under the L/S dah at the brake pedal . Sounds like it might be sticking. Hope this helps

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Check fuel pump pressure and fuel pump regulator. It sounds like you are not getting fuel into the system and if you are you are not getting enough fuel into the system

Posted on Jan 02, 2010

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SOURCE: I have a 1999 Cadillac

There is a problem with the hole getting clogged right by where the engine connection is, use a piece of wire to unclog the orifice and reinstall the line. You should be OK after that.
Good Luck!! A HELPFUL - 4 THUMBS - rating for this solution would be greatly appreciated. Thank you for using FixYa.

Posted on Jan 04, 2011

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