Leaking Transmission Fluid

Transmission Fluid LeakLeaking Transmission fluid can often be more difficult to identify than other types of leaks.  If you have a rear, 4 wheel or all-wheel drive vehicle, the leak point is often right in the middle of your vehicle making it something you probably won’t notice unless you’re regularly crawling under your vehicle.  If you keep up with weekly, monthly and yearly maintenance checks on your vehicle, you just might catch a transmission leak before it becomes a big deal.  For more information on what sort of things you should regularly be checking on your vehicle, check out our series on routine maintenance.

Most transmissions are fairly well sealed and usually don’t start to leak until they have quite a few miles on them, or have not been regularly maintained.  Most people think of changing transmission fluid to help preserve the gears, bands and clutches in their transmission.  The reality is fresh transmission fluid can also help preserve the seals and gaskets in your transmission as well.  The “dirt” in your transmission fluid is actually more wear products that actual dirt or sand.  Unlike your engine, your transmission is a closed system meaning it is very difficult for dirt or dust to get in.  That means the suspended particles in your transmission fluid that turn it brown or black are mostly tinny metal shavings that are worn off gears and bearings in your transmission.  These tinny metal shavings get pumped around your transmission in the fluid and can act like liquid sand paper on the inside of the seals and gaskets causing them to wear out and fail prematurely.  To keep this from happening, make sure you change your transmission fluid at the factory recommended intervals.

The other main reason that your vehicle has started leaking transmission fluid is that the bearing inside have become worn out.  The shafts that go through the seals in your transmission are held in place by bearings so they don’t move in, out, up or down but still allow the shaft to spin freely.  As the bearings become worn due to use, the shaft can start to sag down pulling on the seal and leaving a small space at the top where transmission fluid can leak out.

As you’re checking for transmission fluid leaks the first place to check where the driveshaft or axles exit the transmission.  This seal is the most likely to leak, since it is open to road grime and dirt on one side and transmission fluid on the other.  The other seal that is most likely to leak is where the input shaft goes into the transmission.  This seal will be hidden by the clutch or torque converter and ultimately the bell housing so it can be extremely difficult to inspect without removing the transmission.  Usually if this seal is leaking you will find transmission fluid dripping from where the bell housing bolts to the engine block.  Even though it’s unlikely, it is possible for your transmission to be leaking from one of the seals where the case is bolted together.

All of these seals or gaskets can be extremely difficult to get to without removing the transmission from your vehicle.  That includes disconnected all the axles and drive shafts, removing the transfer case if its 4 wheel drive, removing all the shift linkages, sensors and wiring and unbolting it from the engine.  Once you’ve done all that, which can be hours work, it is also extremely heavy and difficult to maneuver.

Leaking Transmission FluidA much better way of stopping your leaking transmission fluid is to simply use BlueDevil Transmission Sealer.  BlueDevil Transmission Sealer is a completely safe additive that you add to your transmission fluid to stop your leak.  BlueDevil Transmission Sealer is designed to restore the seals and gaskets in your transmission to their original shape and size which can stop your leak permanently.

BlueDevil Transmission Sealer

You can purchase BlueDevil Transmission Sealer directly from BlueDevil here: Transmission Sealer

You can also purchase BlueDevil Transmission Sealer at any of our partnering local auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributer
  • DYK Automotive

Pictures provided by:

transmission_fluid_leak.jpg – By Plik – Licesned by Creative Commons Share Alike 3.0 – Original Link
tTransmission_fill.jpg  – By Paul79uf – Licesned by Creative Commons Share Alike 3.0 Via Flikr – Original Link


24 responses to “Leaking Transmission Fluid

  1. Just put a recon torque converter. After putting some oil in the car have found a pool of oil under the car. Looks like its come from around the bell housing. Have I done something wrong or is something else wrong. Any ideas.

    1. Justin,

      Thanks for your question about your torque converter. Based on your question, we’re assuming that by “oil” you’re talking about transmission fluid. If your car is leaking engine oil after putting a new torque converter on, then you probably damaged your rear main seal during installation. If your car is leaking transmission fluid after installing a new torque converter then you may have damaged the front seals on your transmission or incorrectly installed the torque converter. If you do end up with a pool of transmission fluid without even running your car, we’d recommend pulling things apart and finding your leak as it will likely be a fast leak if you start your engine.

      Thanks again for your question!
      -BD Auto Pro

    1. Ronnie-

      Thank you for asking about your Ford Freestyle. Has any transmission fluid been added recently and potentially the system is overfilled? If not, it is possible that there is some kind of a restriction in the system that is not allowing the fluid to flow properly, forcing it out. Does the fluid loss appear to be coming from one of the seals or is it coming through the cap? Please contact our technical support line at 888-863-0426 so that we can get a better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!


  2. What kinda of guarantee do you guys have in your stop leak? If it makes the leak worse do you guys cover it?

    1. Brady-

      The BlueDevil Transmission Sealer carries a money-back guarantee. If it is unable to seal the leak for whatever reason, you would simply contact our technical support line at 888-863-0426, and we would be able to assist you.

      Thank you!


  3. i have a question i changed out my tranny on my 99 civic (auto) u noe gears slippn,shifting to reverse from parts makes loud bang n whole kar shakes on the new used tranny i put it does same thing slippn,clanging but there is alot of fluid leakin from whole top of tranny where the two connect wat did i do wrong kupd it be from a tranny bein tranny has no fluid

    1. John,

      Thanks for your question about your 1999 Honda Civic. If you’ve got transmission fluid coming from the top of the transmission then it’s possible you forgot to connect the transmission cooler lines or left a plug or sensor off from the top of the transmission when you installed it. A low fluid level could definitely cause the problems you are having, but it’s also possible that the transmission you received was defective or had internal damage before you installed it. We recommend contacting the company you got the transmission from to see if they offer a warranty.

      Thanks again for your question!
      -BD Auto Pro

  4. I have a manual transmission with a fluid leak. Do I have to bring my car to a mechanic to have this fluid installed?

    Thank you!

    1. Danielle-

      No, applying the BlueDevil Transmission Sealer would not require taking the vehicle in to a mechanic. Simply add the product where you add transmission fluid. You will be using one oz. of the product per quart of fluid in the system, and should expect to start seeing results after approximately 100-200 miles of driving.

      Thank you!


  5. My car is seeping tranny fluid at the bottom of my bellhousing where it meets the engine block. Any ideas?

    1. Colton-

      The BlueDevil Transmission Sealer is intended for leaks that are seeping or lightly dripping. Based on your description, you would be a good candidate for the product. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  6. Transmission fluid is leaking from the drive shaft of my car I have changed the shaft seal and even the shaft head it seem to stop for some days but it starts leaking again please any idea what the problem might be

    1. Otokpen-

      Because the drive shaft seal was replaced and the leak persists, it’s possible the leak is coming from elsewhere. As long as you are not losing transmission fluid too quickly, you would be a good candidate for the BlueDevil Transmission Sealer. You would be adding one oz. of the product per quart of fluid in the system, and should expect to start seeing results after approximately 100-200 miles of driving.

      Thank you!


  7. Fluid is coming out of my transmission almost like your picture. It is pouring out of the dust cover between the engine and the flywheel. Would your product fix my issue?
    Thank You
    Terry in McMinnvile

    1. Terry-

      The BlueDevil Transmission Sealer is intended for leaks that are seeping or lightly dripping from the system. Based on your description, you may be losing fluid a little too quickly for the product to be successful. A hard part repair may be your best option.

      Thank you!


  8. Replaced the shift solenoid and a couple others and the filter that goes in the pan because my truck isn’t shifting out of first gear, after putting the amount of fluid recommended back in it still won’t shift out of first but there’s a very small leak of fluid that is at the bell housing and the back of the engine, is that why it’s not shifting? Or is there something else wrong

    1. Thomas-

      If the system to low on fluid, that would be enough of an issue to prevent proper shifting. Have you tried topping the system off with transmission fluid to see if that corrects shifting. For your leak, we recommend using the BlueDevil Transmission Sealer. You will use one oz. of the product per quart of fluid in the system. This will help stop the loss of transmission fluid and should return proper shifting out of first gear. You should expect to see results after 100-200 miles of driving.

      Thank you!


  9. I have a 05 wrx when I start it it dumps transmission fluid on the ground was driving fine but now just revs up but doesnt move now just pours out trans fluid will your product work

    1. Cody-

      Thank you for asking about your Subaru WRX. The BlueDevil Transmission Sealer is intended for leaks that are seeping or lightly dripping. If you are losing transmission fluid at a rapid rate, you would lose the product just as quickly, and wouldn’t be able to keep it in the system long enough in order to get the benefit of using it.

      Hope this helps!


  10. I have a slight leak, very slight in my transfer case in the forward output shaft seal. Would adding an oz to the transfer case stop this leak. My jeep uses the same synthetic transmission fluid as the auto trans.

    1. John-

      Yes, BlueDevil would be able to seal the leak coming from your transfer case. You would use one oz. of the product per quart of fluid in the system. The product is safe and compatible to use with synthetic transmission fluid.

      Thank you!


  11. if my chevy colbolt 2008 cooling hose was leaking and my brother went to change it and tight a bolt to tight and broke it off in the bell housing what will it do to my car

    1. Kellie-

      Thank you for asking about your Chevy Cobalt. This is actually more common than you’d think. As long as he is able to remove the bolt, it wouldn’t cause any harm to the vehicle. Unfortunately, it can be difficult to remove and may require you having the vehicle to towed to a mechanic for assistance.

      Thank you!


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