Crankshaft Seal Problems: What Is It, Symptoms, and What To Do

There are many automotive seals that prevent leaks and keep contaminants out of vulnerable systems in your vehicle. One of those critical components is the crankshaft seal that protects the crankshaft. While it’s a simple and sturdy part, the crankshaft seal will wear out over time and cause serious issues like a crankshaft seal leak. Thus, it’s a good idea to know the warning signs of an old or failing crankshaft seal so that you can replace it as early as possible.

What Is the Crankshaft Seal?

There are seals at both ends of the crankshaft, but the seal on the end where the belts are driven is typically referred to as a front crankshaft seal or a timing cover seal.

Symptoms of a Bad Crankshaft Seal

The crankshaft seals prevent pressurized or splash oil from leaving the engine. The rear crankshaft seal is more failure prone because the journal that spins just in front of the seal (inside the engine) at that point is lubricated from the pressurized oil gallery.

The front seal on an engine with a timing belt plays the same role but is a smaller seal. If the engine has a timing cover (metal timing chain lubricated by splash oil), the seal will only contain splash oil and not pressure.

Below is the main warning sign of a bad crankshaft seal:

Crankshaft Seal leak

If engine oil is leaking from either end of the engine, a crankshaft seal can be the cause of the leak, but the problem with engine oil leaks is that even if they’re coming from much higher on the engine, they tend to drip off the lowest parts of it.

It’s dreadfully common to believe the rear crankshaft seal is leaking because oil is seen dripping from the bottom of the bell housing, when actually the leak is coming from somewhere else. Be careful about misdiagnosis.

Depending on the crankshaft seal’s material, the leak can develop differently. A rubber crankshaft seal can dry out from extreme heat or after long periods of neglect. Once rubber dries out, it becomes brittle, making it more likely to crack or even fall apart.

While a metal crankshaft seal won’t dry out like a rubber seal, it can fail in other ways. Exposure to high temperatures can warp metal and vibrations can stress the seal until fractures appear in the part. If the oil seal uses steel and the anti-corrosion protection gets compromised, the part might also corrode.

Regardless of the material with which the crankshaft seal is made, engine oil will leak out of any damaged section.

You can determine the crankshaft seal leak’s severity by checking the amount of engine oil that escaped through the gap. A minor leak will let out enough lubricant to eventually cover the engine’s bottom in a light layer. As the leak expands in size, more oil seeps out until they form droplets that are visible to the naked eye.

Keep in mind that a bad crankshaft seal isn’t the only possible reason for an oil leak. Engine oil sees use in many other engine parts that have their own oil seals. Run a thorough check on the relevant parts to determine whether or not the crankshaft oil seal is the one that went bad.

What Does the Crankshaft Seal Do?

Anywhere a spinning shaft extends from inside the engine to the outside, there will be an oil seal. Transmissions have oil seals at both ends for this reason.

Seals perform the dual jobs of keeping important fluids inside one of the vehicle’s parts or systems while simultaneously preventing unwanted substances from entering the system.

Seals engine oil in the crankshaft

The crankshaft seal keeps engine oil in the crankshaft. When the crankshaft spins, it will fling away some of the lubricant coating it. The seal keeps the oil from escaping the engine.

By preventing engine oil from escaping the crankshaft, the seal ensures that the shaft stays sufficiently lubricated. The crankshaft needs the oil to stay cool, reduce friction that can slow it down and cause overheating, and prevent metal-on-metal contact with other engine parts.

How Long Does a Crankshaft Seal Last?

Most crankshaft seals are designed to give good service for roughly 100,000 miles. Most will last the life of the engine.

There’s nothing you can do to alter the life of the seal. Seals fail for various different reasons, none of them operator-related.

If the rear seal needs replacing, the transmission and flywheel will need to be removed for access. Unless you’re able to remove the transmission and flywheel safely, this job is best done by a professional mechanic.

Likewise, the front crankshaft or timing cover seal requires the removal of the belts and the harmonic balancer. In some cases, the timing cover will need to be removed, which typically requires removing the water pump and other parts.

Replacing either seal is typically a professional job.

How Much Does a Replacement Crankshaft Seal Cost?

The price tag of a replacement crankshaft seal can vary according to factors like the product’s brand, quantity of seals, and other components included in the set or kit. A new seal can go for a price as low as $3 or as steep as $400.

Where to Get Crankshaft Seals for Your Vehicle

The crankshaft seal ensures the shaft is lubricated, preventing it from overheating due to friction. Overheating could also lead to engine failure, which comes with a hefty repair price. Luckily, getting a replacement crankshaft seal is easy with CarParts.com.

Find and order the perfect replacement seal from the comfort of your couch! Use your mobile phone to visit CarParts.com, and use our advanced filters to select your vehicle’s year, make, model, and engine.

Our crankshaft seals come from the most trusted manufacturers in the industry to ensure you’re getting quality products. Get what you need in a matter of days, thanks to our fast and reliable shipping.

Prevent engine problems by replacing the crankshaft seal before it gets faulty. Check out our wide range of crankshaft seals now at CarParts.com.