How do I fix my leaking gearbox

Greetings Dan,

The first steps in diagnosing a transmission leak is to locate exactly where it is leaking. I understand without access to a lift and certain equipment this can seem like a daunting task. There are a number of seals and gaskets in every transmission that can fail. I am going to list some specific questions you can answer that will help me to help you.

1. First and foremost. I understand this is a Toyota Corolla. What specific year and engine size for this vehicle. ( This allows me to pull up diagrams to look at exactly where a leak maybe occurring.
2. How did you notice this leak what symptoms if any led to the discovery of this leak. Transmission slipping, Red or pink puddle on the ground. Are you sure this is a gearbox leak and not an oil leak etc.
3. Did you check the transmission fluid level? Is it low? do you know the procedure to check the transmission level properly?
4. Is it possible you can provide a picture of the fluid leak.
5. Is there any Codes stored in the computer? Is the car shifting properly?

There is unfortunately no simple solutions for a leaking gearbox. I have heard of people saying that they simply bought a bottle of stop leak from one of the Autozone etc. and that this has stopped the leak. However in 3 decades of working on vehicles in a professional and private capacity I have never once had stop leak actually solve an issue and usually I end up working on the vehicle to change a gasket or a seal etc.

It is not too expensive to simply take the vehicle to your local shop where they have a lift and have the mechanic place it on the lift and give you a full inspection of the gearbox and determine the location of the leak. Otherwise you can purchase or borrow a set of ramps to put the car on and crawl up under it to inspect. I would expect the cost to hover around the $100 - $150 dollar range to have a reputable shop give you an indicator of what is actually going on and what needs to be replaced.

In time this problem will only grow in severity and will cause damage to the transmission. If you choose to borrow or buy some ramps, always good to have a set anyway. Please take the time to be cautious and safe. Pull the car on the ramps and engage the emergency brake and place some blocks behind the back wheels to stop the car from having any ability to move.

You can buy a couple cans of brake cleaner which is what we use to clean the area usually. If you do this from underneath the vehicle take care not to get it in your eyes or breath the fumes as it is toxic and can damage your eyes, a good alternative to this is to simply take it to the carwash and use the wand to clean the underside of all the oil and debris as well as the top end area of the transmission only Its not a good idea to spray the entire engine compartment and wires etc. Just stick to the area where its dirty and the transmission is Once the area is all clean top and bottom take the car for a short drive and return replace it on the ramps and get to looking for the leak again. Make sure and drive it a good couple miles so that the transmission warms up and can start leaking.

If you can respond to some of my questions and give me some more info perhaps i can be more helpful.

I hope I helped you along a little.

Cheers!

Monte