Question about Pontiac Bonneville

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I am drying to diagnose brake problem with 1993 Pontiac Bonneville SE. The brake pedal goes all the way to the floor when pressed. The brakes grab at first, then the pedal slowly goes to floor and brake power decreases. I checked pads and that's OK. The reservoir fills beyond fill line when brakes applied. I suspect the master cylinder, is that correct?

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  • Anonymous Mar 12, 2014

    Had problem happen before filled brake fluid an was fine . Brake fluid was empty an added it still to floor.



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Yes it sounds like the problem it could maybe be the brake booster if the brakes are better at a higher idle but there is a check valve on the brake booster that cost 2.00 too replace that runs off vacume i would replace first

Posted on Jul 22, 2009

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You are correct, the pressure producing seals in the master cylinder are worn out.
Make sure you bench bleed the new master cylinder before installing.
Good luck,

Posted on Jul 22, 2009


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1 Answer

Sometimes it wont come out of park. Its a automatic on the floor

check the start safety switch ,, ( push on the brake a few times that should allow the car to be shifted, ) if not,, check the switch located at the top of the brake pedal ( some are combined switches, one that controls the brake lights and one thats a safety switch for shifting, or it could be just one switch that combines this process

Sep 09, 2011 | 1993 Pontiac Bonneville

1 Answer

I have a 1994 bonneville that you have to push brake pedal to floor and fluid empties within 1 day. Is it the master cylinder or the line?

check all brake lines and wheel cylinders for leakage. if no leaks its probably the master cylinder. symtoms are-- pedal will sink to floor when stopping or not. or master cylinder leaks from behind "it", and runs down brake booster. if booster goes bad the pedal will be very hard! good-day !

Sep 07, 2011 | 1994 Pontiac Bonneville

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How do you change the 3rd brake light on a 1998 Pontia Bonneville Se?


Mar 25, 2011 | 1998 Pontiac Bonneville

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Changed pads and rotors on the front end, and now the pedal basically goes to the floor. It's a 2007 Dodge Caravan SE, and the rotors, calipers, piston covers, bracket, and the pads are all dry rotted,...

try holding the brake pedal down overnight with a broom jammed into the seat ?? if that doiesnt work then bleed the brakes and if still no joy then ask a local mechanic to diagnose for you before you spend a fortune on unecessary parts

Aug 29, 2010 | 2006 Dodge Grand Caravan

1 Answer

Pontiac Bonneville - 92 SE - Brake Problem

Your problem may be a sticking brake booster!

Jul 25, 2010 | 1992 Pontiac Bonneville

1 Answer

I have a 1978 trans am with a 403 and have no brakes. does the booster use manifold or ported vacuum?

You should have brakes, but a really hard pedal to push, if your booster has no vacuum. If your pedal goes to the floor, you need to fix that problem first.
Check all wheel cylinders for leakage, and check the level of brake fluid in the master cylinder.
Your brake booster has a large vacuum hose that hooks directly to the back of the manifold/ carb base assy.

Dec 02, 2009 | 1978 Pontiac Bonneville

2 Answers

My brakes lose pressor

Sounds like master cylinder on it's way out. If pedal pushed, then ease off slightly but keep constant pressure on pedal & it fades to floor, I'd say master cylinder, if no sign of fluid loss.

Jul 11, 2009 | 1992 Pontiac Bonneville

2 Answers

Brakes mushy, fluid a little bit low, but filled

if you can not find a leak then try to bleed your brakes somtimes thell loose pressure but if your fluid goes low then you most likey have a leak the smallest hole anywhere in the brake system will cause this

Jul 09, 2009 | 1994 Pontiac Bonneville

1 Answer

Brake pedal will go all the way to the floor

make sure brake fluid is full. then pump brakes for one minuite check the fluid to see if it went down or stayed full. if it went down then check the system for a leak . if it stays full then you will need a new mastercylender . i dont think you have a vacum problem cause this causes a verry stiff brake pedal not one that goes to the floor

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