Six Signs That Your Valve Seal Is Bad (& Their Replacement Costs)

There are approximately 35,000 parts in a vehicle, including small and large.

There are so many components, so it shouldn't be surprising that certain parts will wear down over time.

Engine wear is the most severe. Some components will lose their integrity as the engine heats and creates lots of pressure.

One such component is the valve seals. They can become damaged by heat or pressure from an engine over time.

The valve seals are vital to holding the engine oil and the car engine’s pressure on separate sides. Although it is rare, bad valve seals can happen in modern engines. Let’s take a quick look at the signs to look for:

Bad valve seals are most commonly accompanied by blue smoke in the exhaust pipe. Inspecting the sparkplugs may reveal oil. You should look out for other indicators such as oily spark plugs, poor fuel consumption or rough idle.

Below is a list that explains the six most frequent symptoms of bad valve seals:

Bad Valve Seals Symptoms

1. Blue Smoke from Exhaust

A bad valve seal can lead to blue smoke in the exhaust pipe. It can be due to a leak in the intake valve seal that causes oil consumption and combustion inside the combustion chamber.

You could also have an exhaust valve leak, which pushes oil out of the exhaust pipe and causes it to evaporate.

The smoke gets worse as the situation worsens. Blue smoke persists for longer and is not affected by high speed.

2. Spark plugs clogged with oil

If you recently replaced your spark plugs and noticed that it was some strange clay on the spark plug tips – it is most likely coming from burnt oil after the combustion.

This oil will cause the spark plug to burn and create clay. Clay will remain there. It is likely that the oil has come from a damaged turbocharger or an open intake valve.

3. Consumption of bad oil

We have already discussed that leaking exhaust or intake valves can cause engine oil to leak into the exhaust pipes.

Normal engine oil contains approximately 4 liters. However, if your engine has leaking seals you might notice a drop in oil.

You should take your car in to a mechanic immediately if there are any symptoms like bad oil consumption.

4. Leakage of external oil

A turbocharged vehicle can push the turbo pressure past the intake valve seals. This causes the crankcase pressure to rise.

The crankcase pressure may increase, causing oil to leak from engine sealings.

5. Rough Idling

When your car idles, a defective valve seal can be easily seen. The engine can often hold a low, steady idling RPM.

If a valve seal breaks or oil enters the combustion chamber, it can cause a rough idle, or even an ejector.

Bad intake valve seals can also cause oil blockage on spark plugs.

You should check the valve seals if you are experiencing rough idle and blue smoke.

6. Loss in Acceleration

It is possible for the valve seals to become so bad, that they block spark plugs and catalytic converts with burned oil.

You may experience a loss of performance or a slower car than normal.

Valve Seals: What do they do?

It is designed to keep the intake flow separated from the exhaust flowing into the crankcase. It is also vise versa – for not letting oil going into the cylinders and out through the exhaust.

A metallic inner ring is used to seal the valve. The rubber sealing material against it is high-heat resistant.

Although valve seals are not likely to fail on modern engines today, it could happen in rare instances.

Valve seal placement

Valve seals can be found in the cylinder head under the valve springs. They are installed around the valves and sealed.

These are under the valve springs. To see them, you may have to take off the valve cover. To reach them, you will need to take off the valve springs.

Valve Seal Replacement Price

The cost of replacing a valve seal is approximately $250 to $2100 depending on your car and labor costs. You can get valve seals for as low as $50-$100. The cost of labor is usually between $200-$2000.

You will need to take off the cover of the valve to access the valve springs.

In many cases, you can pressurize the cylinder chamber to remove the valve springs without removing the cylinder head completely – but sometimes you have to remove the whole cylinder head.

It can be time-consuming and can require a long time to repair the seals.

If you can do the job by yourself, you can do it cheaply because the cost of the valve seals is pretty cheap – it is the time to replace them that costs.

Worn valve seals are not a very common problem and since the high replacement cost – do proper research before you want to replace the valve seals.