5 Symptoms of a Bad Transmission Valve Body
The transmission valve body is a complex maze of valves and solenoids that direct transmission fluid through circuits within your transmission. If the Transmission Control Module (TCM) is the brains of your transmission, the valve body is its heart.
When this component’s valves and solenoids wear out, your transmission will perform poorly or simply stop working. Learn the most common signs of a broken transmission valve body and how much it can cost to repair if you need to replace this complex control unit.
What is a Valve Body? Do not confuse the intake valves and exhaust valves of your engine. The valve body is an assembly in an automatic transmission or CVT transmission that delivers automatic transmission fluid (ATF) to the transmission.
Transmission fluid gets to the right place at the right time using hydraulic circuits controlled by a system of valves and solenoids that direct the flow.
Depending on the position of the solenoid coil, each hydraulic circuit activates a different function in the transmission. Examples of these functions include gear selection, torque converter lockup, and even assisting the ABS system in certain scenarios.
Symptoms of a Bad Transmission Valve Body If you notice the symptoms of a bad transmission valve body, it is usually very obvious. You probably won’t want to leave it alone for too long as it can seriously affect your drivability and cause frustration when changing gears.
A problem with the valve body can also cause limp mode or even incapacity. Below are some of the most common symptoms that can occur due to a faulty transmission valve body:
1) Can’t shift some gears
There are many solenoids that the TCM can turn on and off to control the flow of transmission fluid in the valve body. If any of these solenoids fail, you may not be able to engage certain gears or shift gears at all. For example, if your car can only move in first or second gear, it can be unpleasant for the driver. This symptom tends to get worse if left unattended.
A qualified transmission repair shop may be able to replace a single component of the valve body, or a new valve body may be required, depending on the root cause of the problem.
2) Crackling noises
Do you hear a “crackling” noise when you press the brake pedal to slow down? You may also hear this noise when you put your car in reverse gear and drive backwards. You can also hear it when changing gears.
If the answer to any or all of these scenarios is yes, your transmission valve body may be faulty.
3) Slipping when changing gears
Slipping is another sign of a valve body problem. This means that the transmission speed increases but the car’s speed does not increase proportionately. The valve body contains the critical flow control valve that regulates hydraulic pressure to the transmission clutches. The driver may notice hesitation, loss of power, or even the car barely moving when accelerating, despite high engine rpm.
4) Inability to Downshift
Similar to the first symptom of an inability to shift into a higher gear, loss of ability to downshift into a lower gear is also a sign of a faulty valve body. Downshifting may be attempted automatically by the vehicle when decelerating, or manually by the driver, such as by using a paddle shift.
If the transmission is unable to downshift, hydraulic fluid may not enter or move properly through the transmission valve housing. When this happens, the gears will not be able to receive the proper pressure, which will affect the vehicle’s performance.
5) Switching Delay
Does it take a long time to shift from reverse to forward (or vice versa)? This can also cause you to get stuck in neutral or single gear. It is important not to get too frustrated and to keep pushing the shifter hard until the gear engages. This can cause further damage to the valve body and/or gear shift.