QuestionQUESTION: Roland, my mom has a 1989 ply reliant & the brake peddle is going too low to the floor. It still has brakes but the peddle is too low now. The car is not leaking anything underneath & the fluid levels are ok. A little over a year ago she had the 2 front brake pads replaced but nothing more. Can you tell what the problem might be & how much it would cost to fix it? Its an old car & we were hoping to make it thru the winter with it but maybe not if its too expensive to fix. thank you. Sara
ANSWER: Hi Sara,
Does the brake warning light come 'on' when she steps on the pedal and it goes "to the floor"? If not, then what you may be having is a loss of the power brake effectiveness due to a loss of the necessary vacuum that the engine provides to operate the power assist. The power unit is located in the engine compartment, behind the master cylinder/on the firewall. It has a fat hose that connects to it from the engine intake manifold. Check both ends of the hose to be sure that the clamps are tight and examine the hose for any cracks at the ends and along the length of the hose. Also notice any branch connections off of that hose that might be cracked/broken/disconnected. Let me know whether the brake warning light comes 'on' and we can consider other possibilities.
Roland
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QUESTION: Roland, I want to thank you so much for replying. You are most kind. I went out & looked at the car. No, the brake warning light does not come on when I step on the pedal.
The pedal just goes slowly just about to the floor but
there are brakes. I looked at the engine compartment. I
don't see anything that goes to the firewall because there
is a big plastic thing there, must be where the air cleaner goes. I did see a fat hose that goes up underneath
that. There are some smaller hoses also & I thought I found
one that looked unplugged, but when I moved the end of it, there are wires inside it. Maybe I'm not seeing something.
Would you think it's the master cylinder causing the low
brake pedal? The car isn't leaking & the fluid levels are
ok. If you have any more ideas please let me know. Thank you again for your help! Sara
AnswerHi Sara,
If might be the master cylinder but if that were the case you would be loosing brake fluid and the level in one or the other or both of the brake fluid reservoirs would be dropping. You said the "fluid levels are ok". Does that include the levels in the master cylinder reservoirs? If you have some DOT 3 or 4 Brake fluid fill those until they rise to the lower edge of the inner neck; then recheck them after driving some more and/or pressing on the brake pedal a few dozen times to see if the fluid level has dropped or not.
The master cylinder is mounted on the face of the powerbrake unit so you can't miss it. You will see a round fitting at about 12 o'clock which is the vacuum hose in question which is supplied by a round check valve via a short hose, and then on the other side of the check valve you will see the incoming hose from behind the engine which is attached about mid-line to the intake manifold. You will also see a thin clear tube at the same 12 o'clock location and that is the line that goes in the cabin to operate the air distribution doors. (More about that in a moment).
You will need to remove the rectangular large air intake box which is held in place by three round plastic retainers that unscrew, and then there are two front hoses on box that connect the intake box to the valve cover on the engine, and there is one small hose on the under side (on the end close to the passenger that you will want to feel for and notice so you can reconnect it, BEFORE you lift the air cleaner and filter out of the way as that small hose will disconnect and you won't have noticed it, so you can then inspect that big vacuum hose that goes to the round check valve and its attachment clamp at the other end to the nipple on the rear of the intake manifold.
Alternatively if you know of a competent independent mechanic you could take it to him/her after you verify that you aren't loosing ay brake fluid from the master cylinder. Once you know that, it really does point to a problem with the power brake unit, starting with the issue of the vacuum line.
Do you notice any problem with the air distribution within the cabin like you can't make the blower air go to the windshield or down on the floor or thru the dash vents as requested? If so that too is powered by that same large vacuum hose so that would be corroborative of a loose connection of that vacuum line if the air doesn't get distributed as requested. If the vacuum part of the system seems to be airtight, and you aren't loosing brake fluid, then I would suspect the power unit itself. Check the brake pedal with the engine running because there will not be any vacuum assisted power brake action unless you have vacuum created by the engine running.
Those are some ideas to investigate.
Roland
Thanks for the kind remarks. Please respond via the 'thank/rate' tab if I am not available.
