The valve cover gasket is a seal that sits between the valve cover and your engine. It’s responsible for sealing the oil within the valve cover so it won’t leak out of your engine. As you can imagine, when a gasket starts to fail, it won’t be able to seal properly and oil will start leaking out. There will be noticeable symptoms that affect the car’s operation and you will need to replace it. We’ll discuss everything relating to valve cover gaskets in this post. From why it’s important, the symptoms of a failing gasket, replacement cost, as well as some general knowledge about what it’s for.
Valve Cover Gasket: What are Valves?
As mentioned, the valve cover gasket – or almost any other type of gasket in a car – is a seal responsible for sealing oil within the valve cover and engine. It’s usually made from either cork or plastic and sits between the cylinder head and valve cover. It also acts as cushioning for the valve cover and the engine. But what are valves and how does it work?
Valves are responsible for allowing or restricting fuel and airflow inside the engine. They operate by using the camshaft which has a lobe that mechanically moves the valve to open or shut. An engine has two types of valves: intake and exhaust valves. The intake valve will allow fuel and air to enter the engine’s cylinder, allowing the engine to burn them and create power. Afterward, the intake valve will close and the exhaust valve will open to let the exhaust gas out. Once the exhaust gas is out, the engine can open the intake valve again so the cylinder can burn fuel and air once again. They are typically made of steel, although performance cars might use valves made from titanium.
The valve cover meanwhile is bolted over the camshaft and the valve. The valve cover is necessary so that it will keep the oil inside the engine, keeping the components lubricated. It also prevents dirt from getting into the engine. The gasket helps to seal the gaps between the valve cover and the engine. A valve cover is usually made from either plastic or metal. This component sits on the very top of your engine, and in modern cars, it sits under the plastic engine cover.
Here’s a great video from CNET to help you learn more about how valve cover and variable valve timing work:
Symptoms of a Failing Valve Cover Gasket
The valve cover gasket’s job seems simple, right? All it does is keep the oil inside your engine. But since oil is necessary for the engine’s operation, then a failing gasket can affect the engine in the long run. It will even cause damage to your engine if left unserviced. As with any other critical component, you will see some symptoms when the gasket starts to fail. Here are the symptoms that you might see:
Low Engine Oil Level
As mentioned, the gasket is there to seal the oil so it doesn’t leak out from the gap between the valve cover and the engine. As you can imagine, when the gasket is worn out, the oil will start leaking out. You can check your oil level by using the oil dipstick:
- Make sure your engine is off. If you’ve been driving, let the engine sit for 15 minutes so you can get an accurate reading.
- Locate the engine oil dipstick. It’s usually has a yellow or orange handle with ‘engine’ written on it. If you see a red one, that’s for your transmission oil.
- Pull out the dipstick, wipe it off with a clean rag, and then reinsert the dipstick once again.
- Pull out the dipstick again, and then check the oil level on the dipstick.
- The dipstick should have markers for the maximum and minimum levels. If it’s below the minimum level, then you likely have an oil leak.
Keep in mind that an oil leak may also happen because of a leak in the oil pan gasket. Check underneath your vehicle and see if there are any oil leaks below. If a leak is present, then you have an oil pan leak. Additionally, a blown head gasket may also cause oil levels to drop. This is because the oil will get burnt with fuel when you have a blown head gasket. You will typically see blue smoke coming out of your exhaust when this happens.
In any case, you want your engine oil to always be at the appropriate level. Too much oil will put too much stress on your engine. Not enough oil then your engine won’t be lubricated enough and it can overheat or even damage the engine’s internals.
Dirty Valve Cover
When the valve cover gasket is leaking, you will start to see oil around the valve cover. In modern cars, you may need to remove the plastic engine cover to check this, since it sits on top of the valve cover. Removing the engine cover should be easy, but in some cars, it may require you to remove some nuts and bolts that are holding down the engine cover.
Your engine bay should only be filled with dust. If you see oil and excessive amounts of dirt on the valve cover or dripping down your engine block, then it’s likely you have a valve cover gasket leak.
When oil is leaking from the valve cover gasket, the oil may leak into the spark plug galley and the spark plug tubes. When this happens, it will disrupt your spark plug’s performance. If the spark plug is unable to create a sufficient spark for whatever reason, your engine will misfire.
An engine misfire is when one or more of the engine’s cylinders isn’t firing, hence called a misfire. Because one or more cylinders isn’t firing, the engine won’t produce as much power and it will feel like your engine missed a beat. You will notice the engine idling roughly and your engine may feel hesitant when you accelerate. In this case, it will be because your spark plug isn’t firing enough spark to combust the fuel and air mixture because of the oil seeping into the spark plug tube.
Keep in mind that engine misfires can happen because of other causes. These include a bad spark plug, a faulty ignition coil, and a bad air intake sensor amongst other reasons. But in any case, an engine misfire is a serious issue that can lead to further damage to your engine. In the case of oil seeping into the spark plug tube, it can even create a fire under your hood. So if you have a misfiring engine and see the other symptoms above, it’s best to check your car immediately.
Valve Cover Gasket Replacement Cost
Once you see the symptoms above and verify that it’s the valve cover gasket, your going to want to replace it. A valve cover gasket will cost you around $20 – $50 to purchase. Meanwhile, the labor cost will set you back anywhere between $50 – $300, depending on what auto repair shop you go to. So, that brings the total to as high as $350. A valve cover gasket for a 2010 Toyota RAV4 for example will set you back $23. It’s really quite cheap but the labor is quite expensive.
Valve cover replacement job is not that difficult. However, your mechanic will still need to remove some major parts of the engine to replace it and that may take a while, which is why the labor cost can be expensive. We recommend shopping around a few auto repair shops in your area to get the best quote for your valve cover gasket replacement job. Don’t forget to read reviews of the auto shop online to make sure they have good service.
Reducing Cost: DIY Valve Cover Gasket Replacement
If the labor cost is just too expensive, then replacing the valve cover gasket yourself is always an option. Keep in mind that this is a moderate job to do in terms of difficulty, so you will need the right tools and some mechanical knowledge. If you’re confident and you want to do this job yourself, we’ll provide the steps below.
Before You Start
ExxonMobil, the major oil company, recommends that you try cinching down the valve cover bolts before you actually tear everything apart. The bolts may have loosened or warped over the years and may have been the cause of the leak. Make sure you use a torque wrench and check for the appropriate torque amount specified by the manufacturer. Overtightening the bolts may actually damage the valve cover itself.
If the leak still appears even after tightening the bolt, then you really do have a worn-out valve cover gasket. And this is how to replace them:
1. Remove the Plastic Engine Cover and the Valve Cover Bolts
As mentioned, some cars will have a plastic cover that sits on top of the valve cover. In some cars, you can remove them by hand, or simply remove a few clips. But in others, you will need a socket wrench to remove the bolts that are holding them down. Once you remove the plastic cover, you can begin working on removing the valve cover.
You will need to remove any hose and cable connections into the engine. Remove the vacuum line, and then remove the spark plug cables or connectors. If you have a distributor or ignition-block type of ignition coil, remember to mark the cables so you can reconnect them to the correct spark plug. Your engine can’t run properly if you don’t connect them the correct way.
After that, you can now actually begin removing the valve cover. Spray WD-40 into the nuts and bolts to help loosen them, then by using the correct socket wrench you can start to remove the bolts. You can do it in any order you like, but it’s a good idea to lay them down in a diagram so that you know where the bolts belong when you reinstall them. Just in case the bolts are not the same size. You should be able to find the bolt size in your owner’s manual.
2. Lift the Valve Cover
The next step is to lift the valve cover. If you’re having difficulties, try gently tapping the valve cover with a rubber mallet to help. Once you remove the valve cover, be careful not to drop anything into the engine. This will result in more – and expensive – work and repair jobs.
3. Remove Old Gasket and Remains
Remove the old gasket from the valve cover. Using a pick to lift the old gasket may help. If there are remains or residue from the old gasket, use a plastic scraper to help you remove them. Do not use a metal scraper if you have an aluminum or metal valve cover as this can cause nicks and create leaks. Valve covers are around $50 to replace.
Once you remove the old gasket remains, clean the surface. Wipe any oil off of it and you can use a wire brush to remove any small debris that may remain on the valve cover gasket surface. This step is necessary before you install the new gasket.
4. Install the New Gasket
Before you install the new gasket, it’s recommended that you spray gasket tack to help seal the new gasket. It’s not necessary, but it will help with the process. Afterward, you may need to apply silicone sealant or RTV. Check with your service manual or gasket instructions if you need to apply this and where you should apply it. Do not apply silicone sealant unless the manual says so.
Afterward, you can start installing the new gasket onto the valve cover. Make sure to install it properly, a badly installed gasket will cause further leaks. Take your time and make sure the gasket fits perfectly. Once you’re done, let it sit for a few minutes and then lift the valve cover and turn it over to see if the gasket drops. If it doesn’t drop, then it’s probably good to go.
5. Clean the Cylinder Head and Reinstall the Valve Cover
Before you reinstall the valve cover, you will need to clean the cylinder head. Clean the oil with a rag, and remove debris if there are any. Again, we remind you to be careful and do not drop anything down into the engine. Afterward, check with your manual and see if you need to apply silicone sealant to the surface of the cylinder head.
Next, reinstall the valve cover on top of the cylinder head. Simply put it on and sit it on top of the cylinder head. Make sure it’s aligned with the cylinder head, and then hand-tighten a couple of bolts to hold it in place. Once you’re sure they’re aligned, you can start reinstalling the bolts.
Hand-tighten the bolts first, and you should start from the inside bolts then to the outside. If the bolts have different sizes, make sure you insert them into the correct hole. This is why a diagram was recommended when you remove them. Additionally, these bolts have a torque spec. Consult your manual to find the torque specs, and then you can tighten them properly with a torque-wrench. Overtightening the bolt will cause them to break.
6. Reconnect Hoses and Ignition Coils
Once you reinstall the valve cover, you will need to reconnect the hoses and ignition coils or cables. It’s a pretty easy job, just remember to connect the cables to the correct spark plug so that your engine will run properly. If you have a coil-on-plug or pencil coil system, you can insert them randomly but make sure the connectors are properly installed.
7. Let Sit and Check for Leaks
Once you’re done, you will need to let the car sit for 24 hours so that the RTV/silicone sealant can settle. Afterward, start your engine and drive around in your car. If you don’t see any leaks, then pat yourself on the back because you’ve done a good job. However, if there are leaks, then you may have done something wrong and you will need to do the job again. Or maybe let a professional mechanic do the job for you.
This video below from Car and Driver is a great guide to how to replace a valve cover gasket. Ben Wojdyla uses a Saab for this guide but it’s a great guide regardless of what car you may have:
Questions & Answers
Can I Drive with a Bad Valve Cover Gasket?
You can. Well, sort of. If you see an oil leak but the leak seems to be minimal, then you should be fine and you can keep driving. However, if you see oil and dirt all over your engine bay, and your car is starting to misfire, then it’s really a good idea for you to replace the gasket. As mentioned, a misfiring engine caused by a valve cover gasket leak can lead to a fire and you really don’t want that.
Another way to check if you have a major leak is to routinely check your oil levels. If you’ve topped up the engine oil and it loses it quickly in less than 1,500 miles, then the leak is major and you will need to address the issue.
Are There Cheaper Alternatives?
Other than doing the replacement job yourself? No. Unfortunately, there is no quick and easy, and cheap fix when it comes to a leaky valve cover gasket. You will need to replace the gasket, and either bite the bullet and pay the expensive labor cost or do the job yourself to save some money.
What Else Should I Know?
There are a couple of things that you should know:
- Before you replace the valve cover gasket, check for leaks from other gaskets. If you have a gasket leak, chances are your car is quite old and other gaskets are wearing down as well, such as the oil pan gasket. Check these other parts to see if you have any other leaks. If there are any, you can repair them as well while you’re at it. There’s no point fixing the leak from your valve cover gasket if your oil pan gasket is leaking as well.
- Additionally, make sure there are no signs of a blown head gasket. A head gasket replacement is an expensive job and can cost as high as $1,500 in some cars. This is because your mechanic will have to disassemble the top half of the engine when replacing the head gasket, making labor costs expensive. If you have a blown head gasket, might as well replace it so you don’t keep coming back to the repair shop. Read about head gaskets here to learn more.
- As mentioned, the valve cover has a vacuum line or sometimes called the Positive Crankcase Ventilation (PCV) valve. The valve is inserted into a rubber grommet and the rubber will crack over time and may leak. Inspect the valve and see if you need to replace it as well so you can get the job done in one go. It’s a good idea to fix any other potential problems while you’re working on a major component like the valve cover gasket.
Valve Cover Gasket Wrap Up
As with any other type of gaskets, the valve cover gasket is there to prevent oil from leaking out between the gaps of the valve cover and the engine’s cylinder head. Gasket leaks are normally not a problem for newer vehicles. However, vehicles over 10 years old may experience this problem as the gaskets will start to wear out and leak out oil.
Valve cover gaskets are cheap to buy, but the labor cost makes them quite expensive to replace. Shop around a few repair shops to get the best estimates. Or if you want to save money, then follow our guide above and you should be able to replace the valve cover gasket properly.
In any case, an oil leak is a serious issue and should be addressed immediately. You can drive with a valve cover gasket leak if the leak is minimal, but it’s still a good idea to have it replaced as soon as possible to keep your car running smoothly and avoid further damage to your engine.
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