4L60E Transmission Vacuum Line 4L60E Vent Hose Diagram

The 4L60E transmission is a very versatile and dependable transmission. It is often used in GM vehicles such as the Chevrolet Silverado, Suburban, Tahoe, and GMC Sierra. The 4L60E has been in production since 1992 and is still in high demand today.

One of the most common questions we get at our shop is “What is the proper way to install the 4L60E transmission vacuum line?” We have put together a quick guide to help you with this question.

If your 4L60E transmission isn’t shifting correctly, one of the first things you should check is the vacuum lines. A blocked or damaged vacuum line can cause all sorts of problems, including poor shifting and even transmission failure. Luckily, it’s easy to check the vacuum lines on your 4L60E transmission.

Simply remove the kickdown cable and plug from the transmission case, then unscrew the pressure regulator valve cover. You should see two large hoses attached to the pressure regulator valve – these are your vacuum lines. Visually inspect both of these hoses for any damage or blockages.

If everything looks good, reattach the pressure regulator valve cover and kickdown cable, then start your engine and test drive your vehicle. If you still notice shifting problems, there may be another issue at play – but at least you know that your vacuum lines are in good shape!

Is There a Vacuum Line on a 4L60E Transmission?

Yes, the 4L60E transmission has a vacuum line. This is used to engage the torque converter clutch, which locks the converter up at lower speeds to improve fuel economy.

Which Line on a 4L60E is Return?

There are four lines on a 4l60e: the return, the vacuum, the pressure, and the drain. The return line is the one that goes back to the transmission fluid reservoir. The other three lines are used to connect to various parts of the engine and transmission.

Why is My Transmission Fluid Coming Out My Vent Tube?

If your transmission fluid is coming out of the vent tube, it’s likely because the fluid level is too high. When the fluid level gets too high, it puts pressure on the seals and gaskets in the transmission, which can cause them to leak. If you’re seeing transmission fluid coming out of the vent tube, you should have your vehicle checked by a mechanic as soon as possible.

What Does a Transmission Vent Tube Do?

A transmission vent tube is a small, often clear plastic tube that routes engine vapors from the transmission case to the atmosphere. The vapors are usually vented through a hole in the firewall or fender, and sometimes into the engine bay. The purpose of the vent tube is to allow pressure to equalize inside and outside the transmission case, preventing fluid leaks and keeping gears properly lubricated.

4L60E Vent Tube Diagram

If you’re like most people, you probably don’t give much thought to the intricate workings of your car’s transmission. But if you’re having problems with your 4L60E transmission, it might be time to take a closer look. One potential issue is a clogged or damaged vent tube.

The vent tube is an important part of the transmission system, and its job is to allow air to escape while preventing fluid from leaking out. If the vent tube becomes blocked, it can cause all sorts of problems, including shifting issues and leaks. Fortunately, it’s relatively easy to check the vent tube for blockages.

Simply remove the transmission dipstick and insert a small piece of wire into the opening at the top of the tube. If you feel resistance or encounter any fluid, then the vent tube is likely blocked and needs to be replaced. In some cases, simply cleaning out the vent tube may solve the problem.

But if there is significant damage, it’s best to replace the entire assembly. Fortunately, this isn’t a difficult or expensive repair, and most auto parts stores will have everything you need in stock.

4L60E Blowing Fluid Out Vent Tube

If your 4L60E is blowing fluid out the vent tube, there are a few possible causes. First, check the fluid level and make sure it’s full. If it is, then the next step is to check for leaks in the system.

If there are no leaks, then the problem may be with the pressure relief valve. This valve is located in the transmission and controls the amount of pressure that builds up inside. If it’s not functioning properly, it can cause fluid to blow out the vent tube.

There are a few things you can do to try and fix this problem yourself. First, clean any debris or dirt from around the valve so that it can move freely. You can also try adjusting the spring tension on the valve to see if that makes a difference.

If neither of these solutions works, then you’ll need to take your vehicle to a mechanic or transmission specialist for further diagnosis and repair.

4L60E Vent Hose Size

Most people don’t realize that the 4L60E vent hose size is actually quite important. This hose is responsible for routing excess transmission fluid away from the engine, and if it’s not the right size, it can cause all sorts of problems. The stock 4L60E vent hose is 3/8″ in diameter, but many aftermarket hoses are available in both 1/2″ and 5/8″ diameters.

The larger sizes will provide better flow and less restriction, which can be helpful if you’re running a high-performance setup. If you’re not sure what size to get, err on the side of caution and go with the larger option. It’s always better to have too much flow than not enough!

Transmission Fluid Coming Out Breather Tube

If you notice transmission fluid coming out of the breather tube, it’s important to take action as soon as possible. This is a sign that your transmission is overfilled and needs to be drained. Allowing transmission fluid to overflow from the breather tube can cause serious damage to your transmission.

The high pressure inside the transmission can cause seals and gaskets to blow out, leading to leaks. Over time, this can lead to complete failure of the transmission. If you see fluid coming out of the breather tube, Park your car in a safe place and turn off the engine.

Let the car cool down for at least 30 minutes before starting work. Wearing gloves, locate the fill plug on your transmission. This is usually on the side or bottom of the transmissions case.

Use a wrench or socket to loosen and remove the fill plug. Now slowly open up the drain plug and allow all of the fluid to drain into a catch pan until it runs clear. You may need help doing this if there is a lot of fluid overflowing from the breather tube

Once all of the fluid has been drained, clean off any dirt or debris from around both plugs before replacing them.


The 4L60E transmission is equipped with a vacuum modulator. The vacuum modulator controls the amount of line pressure in the transmission. The 4L60E has a main control valve body and an auxiliary valve body.

The main control valve body controls the shift points and shift feel of the transmission. The auxiliary valve body controls the line pressure and fluid flow in the transmission. The 4L60E has two vacuum lines that connect to the vacuum modulator.

One line is from the engine, and the other line is from the atmosphere. The atmospheric line vents to atmosphere when there is no engine vacuum present. This prevents over-pressurization of the transmission when there is no engine vacuum present.

When you have too much line pressure, it can cause hard shifting and poor fuel economy. If your vehicle has been sitting for a while, it’s possible that your 4L60E Transmission Vacuum Line has become disconnected or damaged. This can cause your transmission to shift hard or not at all.

If you think your Vacuum Line may be damaged, take a look at this quick guide on how to check it for damage!

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Robert is a lifelong enthusiast of all things automotive. He has been working with wiring diagrams and schematics since he was in high school, and continues to use them as the foundation for his knowledge today.

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