Symptoms of Air in Clutch Line

Clutch fluid, also known as brake fluid, is one of the most important liquids in your car’s system. As you continue using your vehicle, the fluid level decreases so you need to refill the clutch reservoir occasionally.

However, low clutch fluid could also be caused by leak in your clutch reservoir at either the master cylinder or slave cylinder.

If you don’t correct this problem, it can lead to serious damage to your car. Watch out for these symptoms of air in clutch line.

Symptoms of air in clutch line

Some clear indications you have air in your clutch hose are:

1. Spongy clutch pedal

If you press down the clutch pedal, it should feel smooth and springy throughout the road. If it feels soft and spongy, it’s probably because there is air in your clutch line.

That consistently spongy feeling is caused by air trapped in your clutch line on the way to the slave cylinder.

As the air compresses, it produces that erratic feel in the pedal. Once this happens, you have to bleed out the air and then top up the fluid to remedy the condition.

2. Difficulty shifting

Difficulty shifting is another sign that there may be air in your clutch hose. If your clutch line is compromised, it will be hard to transport clutch fluid, which will in turn affect shifting.

When you change gears and the transmission grinds notably, you may be dealing with a collapsed or leaky clutch.

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3. Leaks or low clutch fluid

Low clutch fluid is often accompanied with air in the clutch line. Clutch lines are usually made of rubber, which tends to dry and wear out with time.

A worn out rubber is bound to develop leaks eventually. A leaky clutch line will leak fluid and jeopardize the entire clutch system, which needs pressure to operate.

4. Clutch pedal has no resistance

A more severe sign of air in a clutch line is a clutch pedal with very little to no resistance. The clutch pedal can become soft if the clutch hose gets enough leaks or even just one large leak.

This is because there is no fluid and pressure in the clutch system, which means that the clutch pedal will not be able to release the clutch.

A vehicle with a clutch pedal that cannot disengage the clutch is virtually un-drivable.

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How does air in clutch line affect your clutch system?

Your car’s clutch system is designed like that of a brake system. Some systems can actually use brake fluid as the working fluid.

Most trucks and classic cars have a mechanical clutch, which relies on a system of connecting rods, pivot points, and levers to convert the motion of the clutch pedal to the motion of the clutch pressure plate disengaging the clutch.

Modern cars are designed with a hydraulic clutch system as they are much easier to install, durable, and use up less space.

If you have changed the fluid or replaced the master, cylinder, slave cylinder, or the lines, you need to get rid of any air in the system effectively in order for your clutch to work properly.

This process is known as bleeding the clutch system, and is essential because air can cause a malfunction in your hydraulic system.

When you step on the clutch pedal, hydraulic fluid is forced down into the slave cylinder and activates it, pushing the clutch fork and releasing the clutch.

Any air in the system will compress and absorb the fluid flowing from the master cylinder to the slave cylinder.

This prevents the slave cylinder from moving as efficiently as it should, which in turn keeps the clutch from fully disengaging when shifting your transmission.

How to Bleed a Clutch Line with a Pressure Bleeder

To bleed a clutch means to remove then unwanted air trapped in your hydraulic system. Here is how to go about it using a pressure bleeder.


  • A wrench
  • Jack and jack stands
  • Can or cup to catch the fluid
  • Flexible tubing or hose that fits on the bleeder valve
  • A pressure bleeder


  1. Jack up the front of your car and open the hood
  2. Take the cap off of the clutch fluid reservoir and check if the reservoir is filled to the brim.
  3. Screw your pressure bleeder over the reservoir
  4. Press your clutch a couple of times
  5. Pump your power bleeder to a PSI of approximately 12.
  6. Take the following items with you under the car:
  7. Wrench
  8. Cup
  9. Flexible tubing
  10. Find the bleed valve on the clutch slave cylinder. Spray some penetrating oil on it if there is corrosion.
  11. Check if the bleed valve can turn and then place the horse hover it. Prepare the cup for collecting fluid.
  12. Turn the bleeder valve up to ¼ of the way using your wrench and hold. Watch out for air bubbles in the fluid.
  13. When the air bubbles stop, tighten the bleeder valve and take out the tube.
  14. Some of the fluid in the reservoir will be lost, so be sure to top it off to the full line
  15. Now test if the clutch is tight and easier to engage. If the problem persists, you may need to replace your slave cylinder or master cylinder.

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How to bleed a clutch system without a bleeder

You will need:

  • Clutch fluid
  • A wrench
  • An assistant


  1. Check how much fluid is left in your clutch fluid reservoir. It should be filled to the maximum.
  2. Put a pan under the bleeder screw
  3. Have your assistant press the clutch a couple of times, then hold it down
  4. Unscrew the bleeder screw using your wrench, about halfway through
  5. Wait for the bleeding to slow down before you tighten the screw back
  6. Disengage the clutch pedal and increase the clutch fluid
  7. Redo this process until you see only liquid coming out, with no air bubbles.
How to bleed a clutch system without a bleeder

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FAQs on Air in the Clutch Line

Can air in clutch line make the clutch slip?

No, air in the clutch line would not cause slipping. Air would hinder the clutch from releasing all the way.

Why does my clutch have no pressure?

Check and confirm whether the slave cylinder is moving. If not, the slave cylinder could have a leak preventing it from functioning efficiently.

Also, make sure the pin to your clutch pedal is hooked to the master cylinder. If there is no leak, it could be a symptom of air in the clutch line.

When every part of your vehicle is doing its job properly, you not have any difficulty switching gears.

Resistance, stuttering, and slight vibrations when shifting gears are clear signs of air in your clutch hose.

That is why it is important to keep your transmission fluid at the maximum level all the time so that your gear can shift smoothly and efficiently.

Sometimes symptoms of air in clutch line can also indicate low clutch fluid, especially if there is a leak on your master cylinder or slave cylinder.

You need to attend to these leakages as soon as possible as low fluid levels can cause severe damage to your car’s internal components.

You can easily determine whether your car is losing clutch fluid level by dipping a dipstick in the clutch fluid reservoir. Your vehicle will also give you some signs.

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