Engine dies when brake pedal depressed

**shelu** · July 2nd, 2014 09:56 PM

Mga sir, ano kayang problema nito? Ok ang idle ng car ko pero pag inapakan ang brake, patay ang makina. Sabi ng mekaniko, sira daw ang hydrovac, may vacuum loss daw. Kia cd5 ang kotse. Tama kaya ang diagnosis, mga sirs?

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**tidus1203** · July 2nd, 2014 10:00 PM

Originally Posted by shelu

Mga sir, ano kayang problema nito? Ok ang idle ng car ko pero pag inapakan ang brake, patay ang makina. Sabi ng mekaniko, sira daw ang hydrovac, may vacuum loss daw. Kia cd5 ang kotse. Tama kaya ang diagnosis, mga sirs?

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Its also possible that the car has a dirty throttle body??

**sirkosero** · July 2nd, 2014 10:14 PM

check mo muna lahat ng vacuum hoses mo kung nakakabit at walang sira. kung okay pa, tsaka mo tignan hydrovac.

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**shelu** · July 3rd, 2014 05:56 AM

Originally Posted by sirkosero

check mo muna lahat ng vacuum hoses mo kung nakakabit at walang sira. kung okay pa, tsaka mo tignan hydrovac.

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copy. i'll do this today.

**jaypee10** · July 4th, 2014 06:09 PM

try mo nga bombahin ung break pedal mo kung tataas ung idle mo..
kung walang pag babago malamang vacum..

**shelu** · July 6th, 2014 05:15 PM

Originally Posted by jaypee10

try mo nga bombahin ung break pedal mo kung tataas ung idle mo..
kung walang pag babago malamang vacum..

di pwede bombahin ang pedal kasi patay agad ang makina pag apak sa brake pedal.
naghahanap ako ng murang surplus hydrovac, baka ito na nga.

**red_one** · July 6th, 2014 06:51 PM

curious, how can stepping on the brakes shut off the engine? hindi ba separate system ang brakes?

**red_one** · July 6th, 2014 07:18 PM

i continued reading and mukhang nakita ko sagot sa questions ko above. there is one part of brake system that uses vacuum from the engine.

Power Brake Booster

The power brake booster is mounted on the firewall directly behind the master cylinder and, along with the master cylinder, is directly connected with the brake pedal. Its purpose is to amplify the available foot pressure applied to the brake pedal so that the amount of foot pressure required to stop even the largest vehicle is minimal. Power for the booster comes from engine vacuum.

The automobile engine produces vacuum as a by-product of normal operation and is freely available for use in powering accessories such as the power brake booster. Vacuum enters the booster through a check valve on the booster. The check valve is connected to the engine with a rubber hose and acts as a one-way valve that allows vacuum to enter the booster but does not let it escape.

The booster is an empty shell that is divided into two chambers by a rubber diaphragm. There is a valve in the diaphragm that remains open while your foot is off the brake pedal so that vacuum is allowed to fill both chambers. When you step on the brake pedal, the valve in the diaphragm closes, separating the two chambers and another valve opens to allow air in the chamber on the brake pedal side. This is what provides the power assist.

Power boosters are very reliable and cause few problems of their own, however, other things can contribute to a loss of power assist. In order to have power assist, the engine must be running. If the engine stalls or shuts off while you are driving, you will have a small reserve of power assist for two or three pedal applications but, after that, the brakes will be extremely hard to apply and you must put as much pressure as you can to bring the vehicle to a stop.

Automobile Brakes - A Short Course on How They Work | CarParts.com

**shelu** · July 6th, 2014 09:14 PM

does it follow that the hydrovac is defective sir?

**red_one** · July 7th, 2014 12:00 AM

follow these steps to test the power brake booster:

Do-It-Yourself Power Brake Booster Test
Diagnose Power Brakes

however, i haven't read anything that says a defective power brake booster will shut off the engine.