How Long Can You Drive With Bad Valve Seals? Must Read

Valve seals play a critical role in the efficient operation of an automobile engine. They are located in the cylinder head and are responsible for controlling the amount of oil that is allowed to pass through the valves. A worn or damaged valve seal can cause oil leaks, poor engine performance, and increased fuel consumption. It is, therefore, important to keep valve seals in good condition in order to maintain the performance and longevity of your car.
But how long can you drive with bad valve seals? That is what you’re going to learn in this article, and we invite you to stick around until the end to find out what you’ve been looking for.
Table of Contents
- What do valve seals do?
- What causes valve seals to go bad?
- What happens when valve seals go bad in a car?
- What are the signs of bad valve seals?
- A quick fix for bad valve stem seals.
- Can you drive with bad valve stem seals?
- Some related FAQs.
What do valve seals do?

Valve seals are components of an internal combustion engine that are used to ensure a tight seal is created between the valve and the valve guide. The purpose of valve seals is to prevent oil or other contaminants from entering the combustion chamber, which can lead to decreased engine performance and increased emissions.
Valve seals also help to minimize the amount of oil that is drained off during engine operation. Valve seals are typically made of rubber material and are designed to fit tightly against the valve stem and valve guide.
Over time, valve seals can become worn or brittle and will need to be replaced in order to maintain a tight seal and optimal engine performance.
What causes valve seals to go bad?
Valve seals can go bad due to a variety of reasons. The most common cause of valve seal failure is a worn valve guide. Valve guides are metal sleeves that the valve stem slides through. Over time, the guides can wear down and cause the valve stem to move around excessively.
This can cause the seal to become worn and brittle, resulting in a loss of seal integrity and eventually, a leak. Another common cause of valve seal failure is a build-up of debris or carbon, which can accumulate around the valve stem and prevent the seal from making proper contact.
Finally, extreme temperature changes can cause the seal to become brittle and cracked, resulting in a leak.
What happens when valve seals go bad in a car?
When the valve seals go bad in a car, it can cause a variety of issues. Here are some of the common issues that can occur:
- Engine performance will suffer as the engine will be unable to properly draw air through the cylinder. This will result in reduced power, acceleration, and fuel economy.
- Excessive oil burning and smoke can result from the incomplete combustion of the fuel-air mixture.
- The engine can become noisy with a rattling sound as the valves are not sealing properly.
- The engine can become difficult to start as it is not able to draw in the necessary air for combustion.
- The engine will struggle to reach higher RPMs and may even misfire.
- The car may become difficult to drive due to a lack of power and acceleration.
What are the signs of bad valve seals?

Signs of bad valve seals can include,
- blue or white exhaust smoke,
- increased oil consumption,
- rough idling,
- poor acceleration, and
- decreased fuel efficiency.
The exhaust smoke may be a result of oil leaking past the seals, causing the engine to burn the oil. The increased oil consumption could indicate that the oil is leaking past the seals and into the combustion chamber.
Rough idling can result from an uneven air-fuel mixture due to the oil in the chamber. Poor acceleration can be caused by the reduced power output as a result of the oil in the combustion chamber. Decreased fuel efficiency can be caused by the increased amount of fuel needed to ignite the oil in the combustion chamber.
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Will bad valve seals cause low compression?
Yes, bad valve seals can cause low compression in an engine. Low compression can be caused by a variety of factors, including worn or damaged valve seals, worn or damaged piston rings, burned or sticking valves, or a blown head gasket.
A quick fix for bad valve stem seals.
The quickest way to fix a faulty valve stem seal is to replace it with a new one. Depending on the type of seal, this can be done by either removing the old seal and installing a new one or by using a seal replacement tool.
In either case, it is important to make sure the seal is properly seated, and the valve stem is lubricated before reinstalling it. After the seal is replaced, it is also important to check the valve stem for any signs of damage or wear before reinstalling it to ensure it is in good working order.
It takes at most three hours, which means your mechanic’s labor costs will be high. You might be charged $120 or more by qualified mechanics. Your valve stem seals may need to be replaced in the end, which could cost up to $350.
How do you stop a leaking valve seal?
The best way to stop a leaking valve seal is to replace the valve seal with a new one. If the seal is leaking due to wear, it is best to replace the entire valve. If the leak is due to a loose connection, tightening the connections should stop the leak.
Can you replace valve seals without removing the head?
No, valve seals must be replaced by removing the head. But if you still need to do it then, replacement of valve stem seals without removing the heads usually necessitates the use of a few specialized tools.
You should make sure that both of the valves are closed on a specific cylinder. After that, you take out the spark plug and blow air into the cylinder through the spark plug hole.
Can you drive with bad valve stem seals?
Yes, but driving with bad valve stem seals can lead to a variety of problems. As the seals get worse, oil can leak past them and contaminate the intake manifold and intake valves, leading to a decrease in engine performance and fuel economy.
The oil can also enter the combustion chamber and cause a misfire, reducing power and increasing emissions. Additionally, the oil can be burned in the exhaust system, leading to smoke, higher emissions, and poor catalytic converter performance. In order to prevent these issues, the seals should be replaced as soon as possible.
- Oil can leak past the seals and contaminate the intake manifold and intake valves.
- Decrease in engine performance and fuel economy
- Oil can enter the combustion chamber and cause a misfire
- Reduction in power and increase in emissions
- Smoke and poor catalytic converter performance
- Replace seals as soon as possible
So how long can you drive with bad valve stem seals? It is not recommended to drive at least one kilometer. It is just a matter of time until your engine gets damaged and causes you a big cost for repairing the damaged parts.
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Some related FAQs.
Is leak sealer a permanent fix?
It is frequently recommended as a cheap and simple fix by plumbers and even large national boiler maintenance companies. However, even if the sealant does work, it usually only provides a short-term solution. It functions somewhat like a sticking plaster that will eventually come off, causing the leak to reappear.
Can valve seals cause smoke?
The top of the valve cover’s head will retain some leftover oil if a car sits for a long time or over night. The next time you drive, the oil becomes stuck down at the faulty seal and emits blue smoke.