What Causes a Crankshaft Seal to Leak? Symptoms And How To Fix

24 Aug.,2023

 

When you’re driving your car, do you sometimes hear a hissing noise coming from the engine? It might be difficult to pinpoint exactly where it’s coming from, but if you have heard this sound before then chances are that it’s a crankshaft seal.

Crankshaft seals play an important role in keeping the oil inside of the engine and preventing leaks. This article will teach you about what causes a crankshaft seal to leak, common symptoms that may indicate a leak, and how to fix one!

What Does A Crankshaft Do?

The crankshaft seal is a very important part of your engine. Its purpose is to separate the oil in the crankcase from the outside air, and it does this by creating an airtight barrier between these two areas.

When there are no leaks, you will find that everything inside of the engine runs smoothly (and quietly), but if there is a leak then things can get messy quickly!

What Are The Functions Of A Crankshaft Seal?

The primary function of the crankshaft seal is to prevent the oil from leaking. This happens when it is lubricating your engine. The perfect sealing capacity helps in preventing any kinds of unexpected accidents that may put the life of the user at risk.

What Damage Can A Bad Crankshaft Seal Cause?

The crankshaft is the main rotating part inside your engine. It converts the “up and down” motion created by the pistons to rotational energy so that your vehicle can provide power to propel it forward, or power to run any number of accessories such as an alternator and AC compressor.

As such, this component has a tremendous amount of stress placed upon it on a regular basis and will eventually fail if given enough time without proper maintenance.

One of the most common problems associated with the crankshaft, particularly those used in older engines, is wearing on critical surface areas due to a lack of lubrication at key points along its rotation path.

This issue is commonly referred to as “crankshaft seal failure.” When crankshaft seals begin to fail, engine oil is allowed to be pushed past the seal and into the crankcase (the area under your pistons and inside of your cylinders).

If left unchecked, this can cause excessive wear in both components and ultimately lead to complete failure.

Crankshaft Seal Components

A typical crankshaft seal consists of three main components: The outer metal shell which creates the “airtight” space for separating internal parts from external ones; A lip or edge on top where sealant material gets placed around to create an even tighter fit; And lastly, rubber gaskets which help to fill any gaps and keep the oil inside.

How Can You Increase The Life Of A Crankshaft Seal? 

Performing regular oil changes and making sure not to overfill it is one of the most effective ways to increase the life of a crankshaft seal. Wasting the oil will make the parts slippery and reduce their life. You can also check for any cracks or tears that may damage the crankshaft seal over a period of time.

Another way is to avoid driving your vehicle at high speeds after a repair, as it may affect the pressure on these parts inside the engine and cause leaks later on. Keep this in mind if you have been noticing any problems with your car engine lately, as you might need to replace this part soon to keep it running smoothly.

Common Causes of Crankshaft Seal Leaks

There are a number of things that can cause a crankshaft seal to leak, but some of the most common ones are:

  • Worn out or damaged gaskets – this is often caused by excessive heat exposure over time which can wear down the rubber material
  • A cracked shell – if the metal shell on your crankshaft seal is cracked then it will allow air and oil to mix together, resulting in leaks
  • Damage due to foreign objects such as dirt or grit getting into the engine – when this happens, small pieces can get lodged between the seal and crankcase wall which creates friction and eventually causes a leak
  • Excessive wear on the crankshaft itself – if the crankshaft is worn down then it can cause the seal to become loose and start leaking

Is It Necessary To Replace A Crankshaft Seal?

The crankshaft seal is the most important part of your engine. It makes sure that no oil leaks from it at all, which helps in protecting the life of the user. The replacement of this vital part is not necessary for all vehicles as some are built to last long without requiring any changes or fixes whatsoever.

If you are interested in replacing this part, you can easily do it on your own by searching for these parts on the internet.

The perfect working of this part makes sure that your engine remains lubricated continuously without any disruption. If you are not familiar with the process of replacing it or are not able to locate them, you can always get it from a professional mechanic to avoid any sort of problems with your vehicle.

Symptoms of a Crankshaft Seal Leak

If you are experiencing any of these symptoms, there is a good chance that your crankshaft seal has started to leak:

  • Oil leakage around the engine – this will usually be visible as stains or puddles on the ground underneath your car
  • Engine noise – especially when accelerating or turning; You may also hear a hissing sound coming from the engine bay
  • Smoke from under the hood – this could be an indication that oil is being burned off due to increased friction from the leak
  • Reduced engine performance – your car may not be able to accelerate or turn as well as it used to, or you may notice a drop in fuel economy

How To Fix A Crankshaft Seal Leak

If you are experiencing any of the symptoms listed above, there are a few things that you can do to try and fix the leak:

  • Check the condition of your gaskets and replace them if they are worn out or damaged – this is often an easy and inexpensive fix
  • Repair or replace the cracked shell on your crankshaft seal – depending on how badly it’s damaged, this could be a more expensive repair but it will stop the leaks for good
  • Clear any debris or foreign objects from around the seal – this can help to stop the leak if it’s being caused by something getting stuck in between
  • Check the condition of your crankshaft and replace it if it’s worn down – again, this can be an expensive fix but it will solve the problem permanently
  • If you are unable to fix the leak yourself, then you will need to take your car to a mechanic for repair. They will be able to diagnose the issue and recommend the best course of action for fixing it. Prevention is always better than cure, so make sure that you keep an eye on your engine oil level and change your oil regularly to avoid any potential problems!

FAQs

How Much Does A Crankshaft Seal Cost?

The cost of a crankshaft seal depends on the type of material used in its manufacturing process and the availability of spare parts in stores for these repairs. You can also get it customized as per your own requirements, which significantly increases the price of this part.

If you aren’t able to find one local store that is selling them near you, you can also check online for better deals and offers that may fit into your budget nicely.

Is It Necessary To Regularly Check A Crankshaft Seal?

Regular checking will increase the durability of the crankshaft seal, making it last long without any glitches. You can replace this part on your own, but it is always better to have a look at them before taking the final decision.

By checking the condition of these parts, you are making sure that oil leakage doesn’t occur with time and there are no problems with its functionality. This way, you will be able to save money that would otherwise be spent on regular repairs or replacements.

What Are The External Factors That Can Damage A Crankshaft Seal?

The most common factor responsible for damaging a crankshaft seal is exposure to extreme heat conditions for extended periods of time.

If the car is left out in the heat for too long, even if it has been turned off, it may put the crankshaft seal at risk. This can also cause it to melt and damage other parts in the engine, making them less efficient than before.

What Affects Their Durability?

One factor to consider when replacing crankshaft seals is how long they were left on previously because this could have an effect on their durability. Seals are made from different materials depending on who you buy them from and each manufacturer has a recommended shelf life which should be noted somewhere on the package or invoice after purchase.

Seal durometer hardness can also play a part in real life but I’ll touch more on that later. Generally speaking, you want to use an oil seal that’s rated for any motorsports (water/methanol) application due to the harsher environments.

A good example would be using a rubber compound with Mid or High swell characteristics for high boost pressure or high rpm applications because it will stay pliable under extreme heat and loading conditions which in turn extends their life.

How Can You Restore A Crankshaft Seal?

The most common way of restoring a crankshaft seal is by doing modifications to it. The best thing about these seals is that they are available in different sizes and shapes, which allows you to replace them with ease whenever required.

Another effective method is using adhesives and filling materials to make sure that there are no gaps or holes from where oil can leak from your car engine. Heat-shrink tubing should be used for providing an extra layer of protection against any sort of weather conditions that may affect its functionality.

How Often Should You Replace Crankshaft Seals?

Cleaning and inspection of the lower crankcase halves, oil pumps/timing chain covers, and crankshaft seals should always be part of an engine rebuild. The crankshaft seals (aka: main or thrust bearings) are best replaced when the engine is apart simply because they’re cheap insurance.

They typically cost between $50 to $100 per seal front and back but if you think about it like this: wouldn’t you rather spend that money now than go through all the trouble later to change them out?

If left sealed too long; your motor will start seeping oil from around the seal area which leads to a smoky exhaust and eventually becomes a fire hazard due to excessive blow-by outgassing.

In other words, the pistons aren’t burning the oil as it goes past the rings so it’s being blown straight out of the motor. This is why I always recommend to my customers that they drop them in at least every other engine rebuild just for safety’s sake.

What Durometer (Hardness) Should I Use?

Most people assume that you need a harder durometer seal to withstand higher cylinder pressure and temperatures but this isn’t always the case. For example, if your engine is tuned for high rpm applications; it will typically produce more blow-by than an equivalently modified lower rpm motor and vice versa for moderate vs. low rpm setups.

So using a Higher Swelling Seal will actually reduce blow-by because there’s less clearance between the crank flange and seal area which leads to less compression leakage past the rings during low to moderate load conditions such as street driving.

On the other hand, you may actually gain power with a Moderate Swelling Seal in a high rpm, high power application due to reduced cylinder pressure at the top end. This allows for increased horsepower because you can run less spring tension in the ring package which means reduced friction losses.

Conclusion

If you are experiencing any of the symptoms of a crankshaft seal leak, then it’s important to take action and get it fixed as soon as possible. The longer you wait, the more damage that will be done and the more expensive the repair will be.

There are a number of things that you can do yourself to try and fix the leak, but if that doesn’t work then you will need to take your car to a mechanic. Prevention is always better than cure, so make sure that you keep an eye on your engine oil level and change your oil regularly!

Check out more of these related articles:

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