Fixing a transmission leak is a beginner to advanced job for most DIYers. Here’s everything you need to know to fix a transmission leak at home.
- DIY Difficulty Level: Beginner to advanced.
- Time Required: Thirty minutes up to three or four days, depending on the cause.
- Tools & Materials:
What Is Transmission Fluid?
Transmission fluid lubricates the metal parts and bearings inside your vehicle’s gearbox to prevent them from grinding down as they move. It also provides hydraulic pressure and reduces friction to keep the internal parts of your vehicle in top working condition, as well as helps cool your transmission.
Is It Safe to Drive With a Transmission Leak?
When you first notice a transmission fluid leak, you don’t need to stop driving your vehicle immediately, but ignoring a leak can cause catastrophic damage to your transmission. Once a leak has been detected, you need to have your transmission serviced by a mechanic or fix it yourself as soon as possible to prevent further damage.
If the leak is simply because the pan bolts aren’t tight enough, this can also be a quick, cheap fix for you to do at home. If it’s due to a cracked pan gasket, the fix is relatively inexpensive and straightforward for the DIYers of the auto world. If the leak is coming from other places such as a torque converter, you should consider taking your vehicle to a mechanic.
When to Fix a Transmission Leak
Most transmissions require a fluid flush and fill every 30,000 to 50,000 miles, depending on the vehicle manufacturer’s recommendations in the owner’s manual. If you haul a significant amount of weight regularly, you may need to do a flush and fill as soon as 15,000 miles, since this is harder on your transmission.
If you’re experiencing a slow drip of transmission fluid, you have time to set up an appointment with the mechanic or gather the tools and materials needed for a DIY fix. Do not wait too long to get your transmission leak fixed, as it can have catastrophic consequences for your transmission if you continue to drive with a leak.
What Are Common Symptoms Indicating You Need to Fix a Transmission Leak?
Symptoms to watch for in regards to a transmission leak include:
- Fluid puddling under your vehicle
- Fluid level low when checking the dipstick
- Grinding gears
- Clunking sound
- Strange vibration during driving
- Burning smell
- Delayed acceleration
- Making noise while in neutral
- Extreme heat coming from the transmission
Keep in Mind
Always follow the manufacturer’s recommendations for maintenance schedule on your particular vehicle. The make and model specifications will help you determine how to fix a transmission leak. While this article provides the general steps for fixing a transmission leak, it’s always recommended to consult with a trained professional for car repairs.
How to Fix a Transmission Leak
Step 1: Identify the leak
Transmission fluid is a translucent reddish color but can turn dark red, brown, and then black over time, often with a mildly sweet smell. If you’re unsure whether the fluid you’re seeing is motor oil or transmission fluid, use the dipstick for each fluid to check their levels.
Step 2: Locate the source of your transmission leak
Clean the entire underside of your vehicle using brake cleaner or degreaser. Once clean, drive your vehicle around the block and park it over a piece of cardboard to catch the drip. Use a LED flashlight to inspect your transmission components. You may need to use an automotive leak detection kit that utilizes a fluorescent dye to help identify a leak source.
Step 3: Decide if you can fix it yourself
If the source of the leak is a cracked pan gasket or loose bolts, you should be able to DIY this repair quickly and easily with very little spent out of pocket. If you are unable to identify the source of the leak or can confirm that the leak is not coming from a cracked pan gasket or loose bolts, you may want to consult with a mechanic to determine the cause of your leak.
Step 4: Consult the manual
One tool you may want to strongly consider purchasing is a vehicle-specific shop manual that will give you step-by-step instructions on how to perform repairs, including the tools and parts needed. If the repair is beyond your scope of expertise, make an appointment with your local trusted mechanic.
Step 5: Drain the fluid
Use an oil pan or empty container to catch the transmission fluid as you drain it to perform the repair. If all you’re doing is tightening the pan bolts, skip this step.
Step 6: Repair the leak
DIY repairs can include replacing transmission fluid lines, changing the pan gasket, replacing the pan, tightening the bolts, installing new seals, or installing new drain plugs or pan bolts.
Step 7: Refill your transmission fluid
Once the repair has been completed, fill your transmission fluid with the manufacturer’s recommended ATF to within one-half to one quart of its full capacity, start the engine, check the fluid level, and add more until you reach the right amount.
Still Need Help?
If you need help on how to fix a transmission leak, or other vehicle issues, join the FIXD Mechanic Hotline to talk to an expert who can walk you through DIY repairs or answer any questions you may have. Master Mechanics are ready to take your call Monday through Friday from 8 a.m. to 8 p.m.
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