Do you have a transmission fluid leak when parked?

We all have been in this situation before. We park our car and when we move it, we notice a nice fresh drop or a puddle of black-colored fluid on the floor. And this can be the sign of a transmission fluid leak when parked. The puddle can be on the driveway, in your garage, or anywhere you have been parking your car.

And as soon as you see this, you start panicking and think, Oh my god, another trip to the garage with a nice bill at the end. Well, the vast majority of vehicles have different types of fluids. So before you panic, you need to define where the leak comes from and how severe it is.

I provide 5 different reasons for a transmission leak, scroll below and you’ll find these. I also provide some ideas for costs, etc.

How to determine if you have transmission leaks when parked?

That’s the most important point. First, are you sure it is your vehicle that created the puddle? If so, then you need to determine if this is a transmission leak. Then you can define the different steps to provide a cure.

One of the best ways to define if it is your vehicle that leaks transmission fluid is to use some newspaper sheets. Place these under the engine and secure them with a couple of stones. Then go home, have a cup of coffee (or leave it overnight), and come back to check the sheets.

Now, when you come and see that there are drips and stains on the newspaper, you may be in for a transmission problem. What you should be looking for is the color of the stain.

The stain can be reddish, pink, or light brown in color. If it is the case, and the drips appear to become more from the car engine’s center, then the most likely problem is with the car’s transmission.

You can smell the drips to be more precise in identifying the problem. In most cases, transmission fluid is slick like motor oil. In fact, it usually smells like burnt petroleum. And this is most likely to happen if your vehicle has aged.

By the way, you can always use a large sheet of aluminum foil instead of a newspaper. Sometimes I personally use a clean piece of cardboard under my car and leave it parked for the night, just so I am sure there is no leakage.

If you have this far, that means you have a leak and wonder what is the cause. The most likely causes are:

  • Leak in the transmission pan – very probable.
  • Damaged fluid lines or pan gasket is cheap to repair, but you need some work to get it done.
  • Faulty torque converter – That’s a little harder to repair and best to replace.
  • Seals that are warped/worn out – Easy repair but annoying to do and you could definitely do without it.

No transmission leak when parked in your garage – Why?

There are times where you can find a leak under your car while parking outside, but nothing when you park your car back in your garage. In these cases, then you should start thinking about the location you parked your car and it leaking. It may have been that there was a transmission leak when parked on an inclined slope.

Transmission fluid leak when parked on an incline is common and not easy to detect. So, you really need to remember if your car was parked downhill or uphill.

If it is parked downhill, then I can only guess without seeing the underneath of your car. And my best guess would be that your rear (driveshaft) seal is bad (this is called a rear seal transmission leak) or otherwise damaged.

If you parked uphill, it may be that the fluid overruns pass the damaged seal line and spill through it. Usually, when your car is sitting at a level position, the oil may just be the seal. In this case, you’ll not notice the damaged seal as the oil is definitely below the seal.

Now, think about this, you are parked uphill. The oil is above the damaged seal and as such will start dripping. It should be pretty easy for you to tell if a seal is leaking in that position.

Just crawl under your car (I know it’s not a pleasant solution) and look at your transmission or transfer case where your car’s driveshaft connects. If you see a drop, then you are in for repair. Do not worry, it is fairly easy cheap to fix a sealant.

What to do to repair transmission leak when you’re parked?

Now, you have clearly defined that the fluid stain comes from your transmission. The first thing to do before considering any transmission fluid leak repair is to check the fluid’s level in your engine.

If it is too low and you continue driving, you’re probably in for a major repair at a later date. So best to check if and add some oil if required.

You may need to consult the manufacturer’s manual for what causes leaking transmission fluid. In the manual, you’ll also find the different instructions, to replenish the oil. Of great importance, and in order to get a near-accurate reading, you need to park your car and leave it running (now you can measure the oil).

What causes transmission fluid to leak?

The below are the 5 different reasons what cause a transmission fluid leak for a transmission.

1 – First Reason – Transmission Pan or Drain Plug

Transmission oil drain plug leak

This is standard wear and tear. As you clock up mileage, your transmission pan will get older (as we all do) and at some point experience, some wear and tear. And you may ask why this is happening?

Well, the reason is simple. The more you drive, the more your transmission pan gets subjected to projectiles and dirt. And the more of these, the more susceptible to damage rocks, debris, etc. that you find on the road.

With all of the debris on the road, it is usual to find punctures in a car’s pan. At times, we also find that drain plugs or bolts get loose. In these particular scenarios, you’ll get a leak (even a small drop).

What you do not want to have is to be faced with a big rock or other objects under your car at a small, medium, or high speed. This will definitely damage the pan. In this case, you’ll get your transmission to lose fluid quickly. You better stop your car and get someone to give you a lift while your vehicle is being towed away (don’t cry, this is just life). When this happens, you’ll know right away as a red light will come on on your dashboard.

For any small puncture, it’ll probably take you much longer for you to notice.

Now, you may have your drain plug or bolt not tightened properly. Just take a spanner and tighten it. That’s all you need to do.

On the other hand, you may have the plug over-tightened. This can cause a leak too. The usual time this happens is when you just changed the transmission fluid.

2 – Second Reason – The Transmission Pan Gasket leaks

Transmission Fluid Leak gasket failure

This is a very common issue.

There are several reasons for the transmission pan gasket to start leaking. One of them is the gasket being made of poor materials. Another common, use by some unscrupulous people is to fit the wrong size gasket (a bit smaller one instead). In this case, the leak will appear after a while. So you’ll not think it is caused by fitting the wrong size gasket.

The gasket can also be damaged naturally through wear and tear. It may be cracked through time. And a much simpler problem can arise with bad gasket alignment.

There are times, and this is only a few times, where the gasket is constantly exposed to hot temperatures. The gasket will crack or disintegrate slowly till it develops a fault.

The only good news in this is that replacing the pan gasket is a cheap and easy procedure.

I would advise that you replace the gasket without waiting to avoid any future more serious issues.

3 – Third Reason – Seals are Broken

If your car has an automatic transmission, then you may be subject to broken seals.

In its simplest way, all of the automatic transmission seals must sustain hydraulic pressure. Overtime (this can take years), a number of seals will start showing signs of fatigue. They’ll crack and get worn out. This is especially true as they are continuously exposed to heat.

In winter, things get even worse. They are exposed to really cold weather conditions, and the car produces a lot of heat. As such, the seals will expand and contract continuously till they crack.

The bad news is that getting a transmission leak from the seals means you’ll need to check most of the transmission’s seal. And that could take a lot of time.

The common areas for the seals to break are at the input or output shaft. So focus on these two areas first.

Failing so, then you need to check the other potential source of leaks (i.e., pan, driveshaft, sensors, shifter housing seal, plug seals, speedometer input seal, valve body, and tail housing seal).

4 – Fouth Reason – The Fluid Line is Cracked

Transmission-fluid-leaks pipe leak

I really do not like this issue.

When the fluid line of transmission is cracked, you’re in for a difficult repair with tight angles, etc. I’d rather someone else doing it.

Anyway, most of the fluid lines are constructed from steel or aluminum or a derivative of one of these metals.

It is very rare that these lines break up. They are usually made to last. However, and when driving, you may catch some debris and the line gets damaged.

Cracks also appear due to being over-exposed to heat (that’s a not too common failure though).

If the line cracks, it is good news as you have time to see it. However, if it breaks completely, then the oil will drip quickly and you risk to really damage your car.

5 – Fith Reason – Torque Converter Leakage

Your car operates with transmission fluid. And this fluid is going around the transmission system by the torque converter.

There is a fluid pump (known as the torque pump) that pushes the fluid. There are times that the pump gets fatigued and develop a crack. The most likely area for the crack to occur is near the needle bearings.

When this occurs, transmission fluid will happen. And you may be faced with a front pump seal transmission leak.

This is definitely not a simple fix. You are best to take your precious car to the mechanic for replacement.

Taking care of your car’s transmission

There’s no much you can do to take care of your car’s transmission. One thing that I would avoid is debris offroad and on the main road. This will reduce the risk of cracks, breaking, failure, but will not completely avoid any breaking.

Note that your vehicle’s transmission is a piece of fairly complicated machinery. It will be subjected to wear and tear as being exposed to the elements, the heat, and friction generated by its internal moving parts.

What you can do, is to check routinely the transmission fluid level to ensure that it is not dropping below the manufacturer’s guidelines. The old the car, the more checks you perform.

Typical Cost to Repair a Transmission Leak

You are now convinced that this is a leak and in fact, you have found a leak and now you think “How much?”. You’ll find that there is no much difference in price between one garage to another one to repair a transmission leak.

The most likely transmission fluid leak repair cost is between $150 and $200. Now, this does not include the cost of replacing the system. It includes the replacement of the pan bolts, drain plugs, seals, gasket, fluid lines.

If you need to remove the transmission, then any transmission line leak repair cost will increase. You’ll need to think of around $300.

By the way, you can use a transmission leak stopper if there is a small leak or use the appropriate turbo 350 transmission front seal leak.

Inspection Method

It is best to let the auto mechanic search for the fault. They know where to look and what causes the leak.

They usually are quick to spot the location of the leak.

When they find the leak, and if it is caused by a part that is loose, they’ll just tighten it and you’re good to go home.

Now, if the part is damaged or cracked, well they’ll probably give you an appointment as they need to order the parts. As soon as they receive the part, they’ll replace it.

Before doing any of this work, the mechanic will definitely give you how much you’ll have to pay for the repair. And don’t be shy to ask why it is expensive and how much the part costs.

Check that they use the appropriate transmission leak seal if they advise about this.

That’s it for now, the above is what causes transmission leaks. Now you know all about what causes a transmission to leak and you know what to do if you are faced with that problem. Most likely you have to go to a garage.


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