Steam Coming from Oil Cap | Causes & Effective Solutions

Steam of the oil cap is concerning. But, depending on some factors, you can take it easy or go for early action to fix the problem. If the steam is excessive, you need to worry. Moreover, a tiny smooth or white smooth is not a bad indicator of engine or piston ring wear.

Steam coming from the oil cap means something wrong with your car engine components. Moreover, this problem also arises when piston rings wear, and tear or the fuel bypasses through the bad valve seal. Excess engine heat is another cause that helps the cap to steam out.

Now, if the engine produces a tiny white stem from the oil cap, you don’t need to worry. But, when excess steam comes out, and the steam is black, you need to take proper action to fix the problem, which I describe in the following section.

Why Steam Coming from Oil Cap

Why Steam Coming from Oil Cap

Steam coming out from the oil cap means there have something wrong. Here, you will discover 5 core reasons and finally get effective solutions without spending much money.

1. Worn Piston Rings

From any vehicle, you will discover piston rings. It seals inner combustion and separates the crankcase. Moreover, piston rings prevent lubrication oil from leaking from the chamber. But, when the piston rings wear out, they can’t seal, and the oil and gases mix, which burns the oil and produces smoke.

The smoke comes from the cap. When the seal and other things are damaged badly, the oils burn more and more and produce heavy steam. This is a major issue that helps the smoke to come out from the cap.


Piston rings are not permanent on the engine cylinder. Of course, you can replace or repair piston rings without any doubts. It would be best to take your car to the garage and replace the piston ring with a new one.

2. Clogged PVC System

If you failed to apply the above solutions and your car doesn’t come with a worn piston ring problem, you may check out this reason and solution. Some of the cars have PVC systems. It helps the engine to release excess pressure.

But, when the PVC system comes with a clogged problem, it doesn’t release excess pressure, and the steam comes out from the oil cap.


Undoubtedly, you need to remove and clean clogs from the PVC system. To do that, you need to locate a PVC valve. Typically, you will find out the PVC valve from the cover of the intake manifold.

3. Exhaust gases leaking

When exhaust gases leaked, they wore the seal. Leaking exhaust gases is common but produces tiny smoke from the oil cap. It is not a warning, but you have to fix the problem to avoid any problems.


Try to take your car to a reputed automobile shop so that you can easily fix the problem. Moreover, you can also hire an expert person to fix the exhaust seal to get better performance than before.

4. Engine overheating Problem

Engine overheating is a common problem. When you continuously drive your car for a long time with any fault, your engine produces excess heat and increases the temperature.

Most of the time, this problem comes out because of choosing the wrong oil. Moreover, the bad oil system causes engine heat. Overall, it would help if you were only concerned about this matter when you need to drive your car for a long-time.


First, you must consider the right oil for your car. It would help if you considered all temperatures of working oil so that the car engine doesn’t heat. You can also contact your dealer to get the best recommendation.

Low Oil

When your car engine is low on oil, the friction starts to move the components and produces heat problems. They produce a small amount of smoke on the oil cap. The problem is smaller; you should fix the problem as soon as possible.


To solve the low oil problem, you need to refill back to the correct level. Or you can also change the oil and the oil filter completely.

How to Tell If Steam from the Oil Cap Is Normal?

There have some symptoms have which help you to understand whether your steam oil is normal or not. I will share with you only some core signs so that you can easily understand this matter.

First, bad steam always looks like a dark gray color. When you find this color steam from your oil cap, you need to understand that something is wrong.

Secondly, when the steam is bad and comes from your oil cap, the steam should be high. A tiny amount of smoke is not a major sign to tell that the steam is bad enough.

However, you will check out the above reasons and solutions for your vehicle steam which comes from the oil cap. The above solutions are very effective, and you can easily fix them by yourself.

Is It Normal for Steam to Come from Oil Cap?

It depends on the steam type. For example, if the steam comes with white color and produces a tiny amount of steam, you don’t need to concern about the smoke.

On the other hand, when the smoke comes with dark color and produces a high amount of steam, you should be concerned about the steam which comes from the oil cap.

If you think your car produces a high amount of steam and the color is dark gray, you must take proper action to fix the problem. You can contact an automotive shop to fix the problem.

Why Does Smoke Come Out When I Open My Oil Cap?

When you open your oil cap and find smoke, there are several factors that work here. Check out the following list of the reasons which are the main culprit producing the smoke from the oil cap.

  • Low oil problem
  • Damaged seal
  • Exhaust gases leaking
  • Water vapor damaged
  • The engine produces excess heat

These are the common problem that produces smoke from the oil cap. When your car comes with any of these problems, you will get smoke to open the oil cap.

FAQs (Frequently Ask Questions)

Q: What does it mean when I remove my oil cap and smoke comes out?

Answer: When you take your car oil cap off, and smoke comes out, it means that the piston rings are damaged or the engine comes with low oil. Moreover, the water vapor problem is another cause that produces smoke. Overall, heat engine also causes smoke problem.

Q: Is it safe to drive with the oil cap off?

Answer: No, driving with an oil cap off is unsafe. When you do that, you may lose your car engine, and the oil system is also damaged. An oil cap keeps the oil safe when you are driving. It is an essential part of the engine. So, you should not drive with the oil cap off.

Q: What happens to too much engine oil?

Answer: When the engine oil is much over than requirement, the level of the oil pan becomes too high. Moreover, the engine burns more oil and produces smoke which you find from the oil cap. Moreover, putting too much means you lose some extra oil in the car.

Is It Clear to You?

Damaged piston rings, damaged seal, and heat engines are the main cause that produces steam. Every car has piston rings, and the rings are indeed damageable, and you can easily fix them. However, find out the actual problems from the above section and fix them as soon as possible to fix the steam from the oil cap.


I am Engr. Z Eusuf Lubricant Specialist, Mechanical Engineer & has been working with engine lubricants for a long time and knows what makes them work best. I can help you find the right oil for your needs, and I have tips on how to keep your engine running at its best.