Where is the vacuum check valve located on a vacuum assisted brake booster?
Good afternoon, my name is John and I am replacing my power brake booster in my 2007 Lincoln MKX. Was told I need to disconnect the vacuum check valve but I'm not sure where it is located. I have diagrams and what not, but none of them actually say a vacuum check valve. The paperwork I have states that the brake booster check valve must be disconnected from the brake booster prior to removing the master cylinder or the master cylinder seal may be drawn into the brake booster. By chance is the vacuum check valve located with the manifold vacuum hose assembly on the backside of the power b
Experienced mechanics share their insights in answering this question :
The check valve is built into the hose that connects to the brake booster. The hose should be disconnected from the booster connection when removing the master cylinder. If you apply vacuum to the hose after you remove it from the booster, you should be able to hold vacuum on the line indicating check valve is good. If it will not hold vacuum, then you will need to replace the line assembly with check valve built into it. If you need help with this repair, YourMechanic offers a repair and diagnosis service preformed by a certified mechanic that will commute to your location to help you replace your brake booster vacuum pump.
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An easy way to test the operation of the check valve is to disconnect the hose from the brake booster with the engine off (See Image 2). If you hear a whooshing sound when you disconnect the hose, this is an indicator that the check valve is working.
With your engine turned off, pump the brake pedal several times. This will ensure that there is no vacuum remaining inside the brake booster. Press the brake pedal down hard one final time and leave your foot on the brake pedal as you start the engine. Do not release your foot from the brake pedal during this process.
Engine stalling – The brake booster vacuum hose is connected to the engine`s intake manifold. If the hose is damaged or disconnected, it can cause a vacuum leak, which can result in engine stalling.
Master Cylinder-Mounted: These valves are located directly on the cylinder and attached to fluid ports located between the cylinder and brake lines. Load Sensing: These valves are located directly on the frame at the rear end of the vehicle, with a lever attaching it to the suspension system.
Either way, if your vacuum booster check valve is faulty, get it fixed immediately. Sometimes the check valve is built into the vacuum hose and can`t be serviced separately. In this case, your mechanic will likely have to replace both the hose and check valve.
The check valve is designed to suck out air that is trapped in the brake booster without letting additional air enter the cylinder. This protects the brake lines from developing an air bubble which can seriously impact braking performance.
The sensor is typically located in the vacuum line from the vacuum pump to the brake booster. If vacuum levels fall or if the vacuum pressure sensor fails, your car can have an illuminated Check Engine Light and/or a hard brake pedal.
The signs of a failing swing check valve are often audible. When the disc opens and closes repeatedly (because of low-pressure flow) or violently (because of water hammer), it emits a tapping or hammering sound, respectively.
A vacuum pump check valve for automobiles, also known as a vacuum check valve, is a part of your car that`s responsible for making you vacuum pump system work. This valve seals and holds the vacuum flow up for energy-efficient and completely safe operation. You need it, for example, for your vehicle to brake properly.
If a drum brake actuator is used on disc brakes, constant pressure on disc brakes will cause overheating and brake drag. The disc brake actuator does not have a check valve, meaning that when the brakes are released, the pressure in the brake lines should go to zero.
If a drum brake actuator is used on disc brakes, constant pressure on disc brakes will cause overheating and brake drag. The disc brake actuator does not have a check valve, meaning that when the brakes are released, the pressure in the brake lines should go to zero.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Where is the vacuum check valve located on a vacuum assisted brake booster?
ANSWER : The check valve is built into the hose that connects to the brake booster. The hose should be disconnected from the booster connection when removing the master cylinder. If you apply vacuum to the hose after you remove it from the booster, you should be able to hold vacuum on the line indicating check valve is good. If it will not hold vacuum, then you will need to replace the line assembly with check valve built into it. If you need help with this repair, YourMechanic offers a repair and diagnosis service preformed by a certified mechanic that will commute to your location to help you replace your brake booster vacuum pump.
Low brake pedal and anti-lock brakes are not kicking in.
ANSWER : The brake pedal is working to stop the vehicle, but there may be air in the controller unit causing the ABS brakes to not function. I recommend bleeding the brake system from the farthest location from the master cylinder to the master cylinder including the ABS unit. If the brakes are still spongy after a full bleed, then the controller will need to be replaced. If you need further assistance with your brake pedal being spongy, then seek out a professional, such as one from Your Mechanic, to help you.
Brake booster has oil in it. Engine oil.
ANSWER : The vacuum pump was the source of the oil in all probability. Also, check the wastegate vacuum lines for any signs of oil. If there’s any question then I’d suggest replacing them too.
If you’d like a fresh set of eyes on this, consider YourMechanic, as a certified professional can come to you and pinpoint any leaks to give you some peace of mind.
EPC light on 2004 Jetta. Code said brake switch faulty, but brakes lights worked. Replaced brake switch, now no brake lights.
ANSWER : Hi there. The first thing that pops in my mind beyond of what you have listed is perhaps the electrical harness attached to the brake switch. Perhaps the harness itself is damaged or you have an exposed wire, loose ground wire somewhere. You might want to have a professional mobile mechanic come to your location and complete a brake lights not working inspection to help you diagnose this issue.
Brake lights stay on all the time.
ANSWER : Hi there. The most likely cause for the brake lights staying on is, a faulty brake light switch. Another possibility, would be a short to power past the brake light switch and disconnecting the brake light switch would isolate whether, the short to power is past the switch. Circuit tests should be performed to prove the diagnoses and avoid unnecessary repairs. I recommend having your vehicle’s brake lights stay on be diagnosed and repaired by a certified technician, such as one from YourMechanic.
I have no brake lights and third brake light I have checked all fuses and brake pedal switch and the switch is fine and I’m still
ANSWER : Hi there. Well, you’ve listed most of the usual suspects including the brake switch, fuses and tail light assembly. However, one item you might want to also check is the accessory electrical relay. In some cases, the relay that supplies power from the brake switch to the tail light assembly will cause the issues you are describing. I always recommend that home mechanics purchase a service and repair manual for their vehicle to have a schematic accessibly, so it might benefit you to purchase one online to locate this relay or feel free to have one of our mobile mechanic some to your location and complete a brake light inspection, so they can help trace this issue for you.
Hard brake pedal and rear brakes locking up.
ANSWER : Hi. I will help you with this issue you are having with your 2001 Durango. Unless you bled the master cylinder, it is possible there is still air in the system. If you car is equipped with ABS, air could have also gotten trapped in the ABS modulator. If ABS equipped, a bi-directional scan tool would be essential to manually activate the ABS system to clear air from that segment of the lines while you are bleeding the system. It is also possible that in all of this work somehow the proportioning valve has been affected causing the desired pressure differential, front versus back, to get out of spec. Using a 2,500 PSI gauge, you can check the pressures at each wheel and that will definitely give you a clue as to which brake circuit is the issue (or both), whether the proportioning valve is working properly and whether the line pressures at each wheel are within spec. Should you need a second opinion, by all means feel free to contact YourMechanic for assistance and we will diagnose and repair the issue for you.
When I put my foot on the brake my back left brake light goes off, when I take it off the brake the brake light comes on
ANSWER : I would suggest trying to disconnect and reconnect the wiring to the rear lights. I have seen these older Toyota vehicles rear lighting short out on the lights themselves due to the way the light circuit was made on the lamp housing. Look at the housing circuit on the light to see if one is touching another, and that could tell you why it is malfunctioning. There could also be a problem with the brake light switch. If you are not comfortable dealing with wires, I recommend getting in touch with a certified mechanic who can look at your brake light issue for you to see what’s going on.
