6 Bad Valve Seal Symptoms (and Replacement Cost)

A vehicle has about 30,000 working parts, both large and small.

With so many parts, it should come as no surprise that some parts wear out over time and need to be replaced.

The greatest concentration of wear and tear on a vehicle is in the engine. As the engine heats up and builds up a lot of pressure, some components inevitably lose their integrity.

Valve seals are one of those components that can be affected by the heat and pressure of an engine over a long period of time.

Valve seals are vital to keep the engine oil and the car’s engine pressure on different sides. It’s not a common occurrence with bad valve seals on modern engines, but it does happen. Let’s take a look at the signs to look for:

The most common symptom of bad valve seals is blue smoke from the exhaust pipe. You may also notice oil on the spark plugs when you inspect them. External oil leakage, low fuel consumption or rough idling are other signs to look out for if your valve seals are bad.

Here is a more detailed list of the 6 most common symptoms of a bad valve seal:

Bad Valve Seal Symptoms

1. Blue exhaust smoke

The most common symptom of a bad valve seal is blue smoke from the exhaust pipe. This can be caused by a leaking intake valve seal, causing the engine to consume oil and burn it in the combustion chamber.

It could also be a leaking exhaust valve seal, pushing the oil straight up into the exhaust pipe and causing it to evaporate.

As the problem gets worse, the smoke gets worse and worse. You will notice that the blue smoke lasts longer than before and does not disappear even at high speeds.

2. Oil clogged spark plugs

If you recently replaced your spark plugs and notice foreign clay on the spark plug tips, it most likely comes from oil burned after combustion.

This oil will burn in the plug and produce clay, which stays there. This oil most likely comes from a leaking intake valve seal or a faulty turbocharger.

3. Poor Oil Consumption

As we discussed earlier, both a leaking intake and exhaust valve will cause engine oil to enter the exhaust pipe.

A normal engine contains about 4 liters of engine oil and if you continue to drive your car with leaking valve seals, you can notice the oil level.

If you notice low oil consumption along with any of the other symptoms here, it’s a good time to have your car checked out by a mechanic.

4. External oil leaks

If you have a turbocharged car, the pressure from the turbo can get past the intake valve seals if they are worn, causing pressure to build up in the crankcase.

Increased crankcase pressure can cause external oil leakage from various engine seals and even cause the seals to come completely out of the engine.

5. Estimated Inactivity

A bad valve seal is easily noticed when your car is idling. A car’s engine is often prone to maintaining a constant low RPM and idling speed.

Therefore, when a valve seal is faulty and oil enters the combustion chamber, you may notice a rough idling speed or sometimes even seize up.

It can also be caused by oil trapped on the spark plugs, caused by bad intake valve seals.

If you are experiencing rough idling and blue smoke, it is definitely time to check your valve seals.

6. Acceleration Loss

Valve seals can also be so bad that the valves, spark plugs and catalytic converter become clogged with burnt oil.

This can cause a major performance problem with your car and it can feel much slower than usual, especially if your catalytic converter is clogged.

The function of a valve seal:

The valve seal is intended to separate the intake flow and the exhaust flow entering the crankcase. It’s also the vise upside down so oil doesn’t get into the cylinders and out the exhaust.

Valve seals are made of a metal outer ring and a heat resistant rubber seal against the valve.

Valve seals rarely go bad on modern engines, but it can happen in some rare cases.

Valve seal location

The valve seals are located in the cylinder head, below the valve springs, installed around the valves and seal.

They are located under the valve springs, so you may need to remove the valve cover to see them. They are located under the valve springs, so you will need to remove the valve springs to access them.

Valve Seal Replacement Cost:

The average valve seal replacement cost is between $250 and $2100 for all valve seals, depending on the car model and labor costs. Valve seals are inexpensive, and you can expect them to cost $50 to $100 for all of them. Labor costs are usually between $200 and $2000.

To replace the valve seals, you will need to remove the valve cover to remove the valve springs so you can access the valve seals.

In many cases you can pressurize the cylinder chamber to remove the valve springs without removing the cylinder head completely, but sometimes you will need to remove the entire cylinder head.

This can of course be time consuming and can take many hours to replace the valve seals.

If you can do the job yourself, you can do it cheaply because the cost of valve seals is quite low; It’s time to replace them, that costs.

Worn valve seals are not a common problem and due to the high replacement cost, you should do good research before replacing valve seals.

Leave a Comment