Skip the auto shop - Our mechanics make house calls

How Long Does a Proportioning / Combination Valve Last?

Proportioning / Combination Valve

Modern brake systems are far more advanced than they were even a few years ago. Today, most cars come with front disc and rear drum brakes (although many also come with four-wheel disc brakes). In a disc/drum combination system, there are quite a few different parts needed to ensure safe operation. One of these is the proportioning / combination valve.

Your car’s proportioning / combination valve actually does quite a few different things. First, it acts as a metering valve for brake fluid. Second, it works as a pressure differential switch. Finally, it serves as a proportioning valve. The first function is needed to combat the tendency of disc brakes to engage before drum brakes (providing safer, more even stopping).

The pressure differential operation is needed to warn the driver about brake fluid leaks. If the pressure drops below a certain point, the valve’s piston is pushed off center, and the Brake Light on the dash is turned on.

As a proportioning valve, it helps to reduce the amount of fluid pressure sent to the rear brakes. Drum brakes require less pressure to operate, and if the same amount of pressure is applied to both the front and rear, it could result in the drums locking up.

The proportioning / combination valve is in use every single time you press the brake pedal, and it’s also active when the ignition is on even if you’re not pressing the pedal (certain aspects, such as the pressure differential operation). This means there’s a great deal of wear and tear on the component. In theory, a proportioning / combination valve might last the life of your vehicle, but they generally don’t.

If the valve fails, you may notice any number of potential problems. Knowing the signs and symptoms to watch for that might indicate excessive wear on the valve is important. They include:

  • Brake Light on in the dash
  • Rear drum brakes lock up easily
  • Excessive wear on front pads
  • The front of the car dives down when braking
  • Brake pedal feels soft or spongy

If you’re experienced any of these symptoms, a certified mechanic can help inspect and replace the proportioning / combination valve, as well as any other parts, if necessary.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance Related Trouble Codes: P2158: Vehicle Speed Sensor B P2160: Vehicle Speed Sensor B Circuit Low P2161:...


Related questions

Q: Variable valve timing

The protocol depends on the codes that have set, which are quite varied. Problems with these systems on your particular model and year can stem from blocked oil passages to failed solenoids to wiring harness issues, not to mention mechanical...

Q: Car stuck in limp mode

It sounds like one of the shift solenoids is not functioning properly. I would recommend having a technician come out from YourMechanic and pull the codes on the computer, replace the shift solenoid, and change the transmission filter and fluid....

Q: Hello, I have a 1997 Nissan Maxima and it has no compression reading from cylinder #2.

Hello. It is possible that you have a bent valve but instead you may have a warped valve seat. Whether or not that is the case what is most likely causing the lack of compression in your engine is a...