Why Your Truck is Leaking a Red Fluid (and is it Safe to Drive?)

Why Your Truck is Leaking a Red Fluid (and is it Safe to Drive?)

Oil and mud contaminated truck engine and transmission - truck leaking red fluid
Oil and mud contaminated truck

It’s especially alarming if you see your truck leaking red fluid. What does that even mean? And is it safe to drive your truck despite this leakage? 

In this article, we answered those questions for you. We also listed other types of leakage in your truck and how to prevent them from happening again. 

Table of contents

Jump to your preferred topic. 

What is the Purpose of a Transmission Fluid?

Hand pouring transmission fluid through a funnel as for the good car maintenance - truck leaking red fluid
Transmission fluid for good car maintenance.

The transmission fluid is either a green or red liquid that has a thick consistency. 

Its two main types are manual or automatic. Some manufacturers require more specific transmission fluids such as Highly Friction Modified (HFM) fluids, Type F, Hypoid Gear Oil, Motor Oil, Dexron/Mercon, and Systemic. 

Since the automatic transmission fluid (ATF) is more commonly used in trucks, we listed its functions here, which are:

  • Lubricates the components of the transmission, making sure it functions well as a whole. 
  • Sends power to the engine. 
  • Acts as a coolant, which helps prevent your truck from overheating. 
  • Serves as a hydraulic fluid for power steering systems.
  • Since it can have anti-wear additives, dispersants, and surfactants, it can prevent metal components from deteriorating. 
  • Enhances the transmission’s performance with its chemicals, with the strength depending on the transmission’s requirements.

Why Your Truck is Leaking a Red Fluid 

When you see your truck leaking red fluid under it or seeping at the front, it can either be the transmission fluid or the power steering fluid. 

Transmission Fluid Leak

Drain the old used transmission fluid before adding the new as for the good car maintenance - truck leaking red fluid
Draining transmission fluid.

If you see a pool of red fluid under your truck, your transmission might be in trouble. Some of its components might have been impaired, causing the green or red liquid leakage. 

For example, loosening drain plugs might be causing the leakage. You must tighten it adequately to stop the leaking. On the other hand, don’t tighten it to the point of no return—this can cause leakage, too! 

Another reason for a truck leaking red fluid might also be a malfunctioning or a poorly designed pan gasket. Chances are your truck might have one as a factory defect—and you need to replace it.  

Your truck’s transmission can also leak because of a leaky seal. Now, most large trucks have automatic transmissions and a number of their seals will support hydraulic pressure. With constant heat damage, these seals will eventually crack, causing the leakage.

It’s also possible that road debris punctured the pan or it has taken its toll due to wear and tear from old age.

Finally, you might have a malfunctioning torque converter. If it becomes defective, your engine won’t receive the power it needs to function properly. Besides the fluid leaking, your truck’s gears will easily slip and it will occasionally overheat. 

Power Steering Fluid Leak

Power steering fluid cap with a warning label - truck leaking red fluid
Power steering fluid cap with a warning label

If you see red fluid leaking at the front, then your power steering might be having trouble.

The power steering fluid can also be pink or even colorless sometimes. Besides the leak, you can conclude that you’re running low on power steering fluid when you hear a whirring sound and/or smell burning oil. 

When this fluid leaks, most probably the problem stems from a damaged hose or the seals and O-rings breaking down. 

Without a proper amount of this fluid, the steering system would have a hard time propelling your car to any direction properly. That’s why you must refill this liquid immediately. 

Moreover, without the proper level of fluid, the pump will be overworked. As a result, it will overheat. Therefore, don’t procrastinate on giving this notice. Act now and go to your nearest mechanic for a repair or refill.

Is it Safe to Drive with Transmission Fluid Leakage?

It’s not dangerous to drive with this kind of leakage in the meantime. Particularly, if you’re seeing small drips, you can still drive home and wait for tomorrow for a mechanic to check on it. 

Nevertheless, if you leave it unattended, the fluid will eventually run out, giving you engine and driving difficulties. For example, your truck’s speed will not be coherent with the gear acceleration. 

Worse, your transmission will become defective if you ignore this problem. Plus, don’t forget that the red fluid will make a stain on your garage floor, and it will be hard to get rid of. 

It might not be unsafe now, but prolonging this problem will inevitably endanger you and your car. Therefore, it’s best if you act right away, and call a mechanic for a quick repair or refill. 

What to do with Transmission Fluid Leakage

You shouldn’t let your transmission run with low-level transmission fluid. This will damage the device significantly. Inevitably, you will spend more on the repair. 

If you have extra time, you can check your transmission fluid level. With your engine still running but your truck parked, make a quick inspection using a dipstick. 

Now, to seal the worn gaskets, you can buy a transmission sealer and apply it to the damaged components. That should seal them and stop the leaking.  

Meanwhile, to prevent any leakage from happening again in the future, it’s best if you follow your required maintenance schedule closely. 

We know, it can be a pain; but prevention is better than cure and costly repairs, right? Therefore, see to it that you give your truck some TLC. Adhere to its service schedule.

Other Types of Leakage in Trucks

Besides your truck leaking red fluid, it can also leak other differently hued fluids. Here are some of the common ones:

1. Radiator coolant 

Green radiator coolant
Radiator coolant

When a truck’s radiator coolant leaks, you can expect costlier fees because the mechanic may have to open it and do some soldering. Alternatively, you can also go DIY if you’re tight on budget. 

The possible cause for this might be a worn head gasket. Its function is to provide compression and prevent the coolant’s leakage. Therefore, if the coolant is leaking out of your engine, it’s probably what caused the leakage. 

Now, if your truck is old, head gasket damage is common. 

To stop the leaking, you should buy a sealer for the cooling system. If the damage is really bad, then you might need help from an experienced technician in soldering the head gasket. 

You can find plenty of affordable brands on the market, such as the Steel Seal 8 Cylinder or the BlueDevil Pour-N-Go Head Gasket Sealer. 

2. Antifreeze 

Are you smelling something weirdly sweet after you switched off your engine? 

That is not the Krispy Kreme doughnut you’re eating. That might be the antifreeze leaking.

Now, there are a few reasons why your antifreeze has leaked. First, you might have a broken cylinder block, a blown gasket, or a busted hose, which you can easily observe from the leakage outside of your truck. It’s also possible that you have a loose or damaged radiator cap. 

Is this leakage dangerous? It’s not that severe, but it’s best if you get it fixed immediately. 

Lower amounts of antifreeze will inevitably lead to overheating. It might also impede your car from functioning, as it might mix with the engine oil. 

To fix this, you can do it on your own by buying a new radiator cap and a leak sealant. However, it’s better if you let a mechanic check the issue first—it might be graver than usual.  

3. Rusty radiator leaking antifreeze

Close-up white expansion tank with pink antifreeze. Car coolant level in radiator system in car, automotive part.
Car coolant level in radiator system in a car

Are you seeing an orange liquid leaking out of your truck? That might be your corroded radiator, leaking antifreeze.

When the inside part of your truck’s radiator corrodes, this will cause an internal or external leakage. The latter is usually easy to spot, but the former isn’t. 

To find where the antifreeze leaked inside your engine, check the components nearby the radiator and observe which of them developed rust. 

Moreover, if your truck is old and constantly driven on rough roads, the radiator might have been punctured by road debris. This might have caused the leak.

Meanwhile, you must prioritize replacing your truck’s corroded radiator. Prolonging it will eventually cripple your truck’s cooling system permanently. 

4. Windshield wipers/washer fluid

If you notice some blue liquid leaking out of your truck’s front windows, that’s nothing else but the windshield wiper fluid. 

The causes might be:

  • your rough usage
  • a fuse blown in the pump
  • the washer fluid tank being damaged
  • a broken rubber hose
  • or simply your truck’s old age. 

Specifically, your windshield wipers’ fluid reservoir will eventually degrade, as well as the tubings. When damaged, both of them will cause the blue liquid to leak. 

This problem is pretty common among commercial trucks; nonetheless, you shouldn’t brush it off since it might become a real driving hazard. 

To fix this, you might need to repair or replace some of your windshield wipers’ parts. You might have to reconnect the broken rubber hose or replace your windshield’s pump. 

5. Brake fluid 

Auto mechanic topping up brake fluid in a vehicle
Auto mechanic topping up brake fluid in a vehicle

Your truck’s brake fluid works hard the most, so you have to be alarmed once you notice it’s leaking. Without it, your brake pedal is basically useless.

The brake fluid helps in sending the force when you step on the brake pedals, stopping or slowing your truck. Therefore, if it leaks, you should replace the broken part or refill it instantly. 

Additionally, it’s not safe to drive your truck when this fluid leaks.

The root causes for a brake fluid might be the following: 

  • Your truck’s brake pads are already worn. 
  • The brake line is damaged. 
  • Bleeder valves are deteriorated.
  • The piston seal was punctured by something. 
  • Your wheel cylinder seal has been broken. 
  • Heat damage on the Master Cylinder Reservoir. 

There’s no reason for you to prolong this concern. It can be tricky since brake fluid can either be colorless or dark-brown. Therefore, you should stop driving in the meantime. Call a mechanic and let him or her inspect if you’re having a brake fluid leakage. 

RELATED: This is why trucks have air brakes

6. Gear lubricant

The gear lubricant or gear oil is typically found in the transmission. It helps the hypoid bevel gears slide together smoothly. As a result, you constantly need to replace this fluid at least once a year. 

You will know it’s a gear oil leakage because of its light brown color and awful smell. Usually, the leakage comes from the main seal or a damaged gearbox cover. 

Now, you need to troubleshoot this leakage immediately—the smell can get really terrible.

Moreover, you should protect the final drive from accumulating contaminants, which a gear oil leakage can easily allow to happen. 

When you take your truck to a service center, expect a part replacement and not just a fluid refill. 

What causes water leakage in a car?

If you see a colorless and odorless fluid leaking from your truck, that might be the cooling system’s water. Your windshields and exhaust will also leak water from time to time. This is pretty normal—you shouldn’t worry about it. 

How much does it cost to repair a transmission leak?

You can stop transmission fluid leakage on your own by buying a sealant. You can buy affordable ones on Amazon for no more than $30 per bottle. Meanwhile, you can also spend on repair for more than $100. If you send it to an authorized service center, you will pay more.

How do you stop transmission fluid from leaking?

You can use sealants to stop the fluid from seeping out of your truck. The most beloved transmission fluid sealant brand is BlueDevil Transmission Sealer. The product is specifically designed for seals and gaskets. 

Final thoughts

You should never ignore any type of leakage, regardless of the color or the smell. If you still have time, cease driving first. Some leaks are totally hazardous for driving. 

Therefore, open your smartphone and then call a mechanic, so he or she can make a quick inspection. 

Have you seen or smelled leaking in your car? Let us know by sharing your experience in the comments below!

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