What Causes a Burnt Valve? Here’s Everything You Need to Know
A burnt valve in your car is a very common issue, but not one that should be ignored. Usually, a valve will get burnt because of –
- Faulty components
- Little to no maintenance
- Malfunctioning cooling system
There are other reasons as well, and the fixes are usually costly. But with proper maintenance and constant lookout for the causes, you can stop this from happening to your car. Let’s take a look at all the details on a burnt valve.
How to Detect a Burnt Valve
There are a couple of signs that directly indicate that the valve is burnt. Here’s what to look out for:
Decreased fuel economy
You might notice that even after traveling small distances, a lot of fuel gets used up. This is typically an indicator of a burnt valve.
Loss of power
While accelerating or driving uphill, you may notice a significant loss of power. You might also notice the RPM range showing inconsistent levels of power. These are clear indications that something is wrong with the car’s valve.
Lots of smoke
Exhaust fumes are normal, but too much smoke coming out of the exhaust is not a good sign.
When there is a lot of strong-smelling smoke coming out of the exhaust, then the first thing you should check on is the valve. The smoke will also be visibly gray or white in color.
The valve making unusual noises
When a valve is burnt, there will be too much pressure building up in the combustion chamber.
As a result, a noise that sounds like air escaping will come from the valve area while your car is accelerating. Due to the excess pressure, the air will try to escape past the valve, which is what causes the unusual sound.
Loud knocking noise from the engine
Another type of noise you might experience is something similar to solid knocks on a door.
This also happens when there is an excess buildup of pressure in the combustion chamber, causing the air to escape away from the valve. So, when the piston moves past the valve, it will create a knocking-like noise.
Check engine light goes on
The dashboard message might not directly indicate a burnt valve but will warn you against an issue with the engine control unit (ECU).
A check light will appear on the message board, and this means that something is wrong and you should take a look immediately.
What Causes a Burnt Valve?
Burnt valves are caused by many different issues, normally which include defective car components, excessive heat buildup, and insufficient maintenance. Below are the most common causes for a burnt valve:
1. The wrong ratio of air and fuel mixture
A healthy engine needs the correct amount of air and fuel for it to work efficiently. When the proportions aren’t correct, the imbalance will generate too much heat within the engine and eventually burn out the valve and some other components.
It is very important to check the air filter and engine management system for any problems.
2. Defective exhaust valves
As time goes by, exhaust valves will wear out and lose their initial shape. The valves will usually expand and let in too much heat into the cylinder than normal. The extra heat that has entered will eventually burn out the valve.
3. An incorrect gap of spark plug
In some cases, your car’s spark plug gap might not be the right size for the engine. An incorrect gap can allow too much oxygen to get into the cylinder. This is very risky as it can lead to pre-ignition of the engine.
If the engine is ignited earlier than intended, the piston will rise and fall at a faster pace. This will generate excess heat in the cylinder. Overall, the combustion chamber will get overheated and lead to the burning of the valve.
4. Not enough cooling
The engine will generally get hot because of the fuel it needs to burn and the work it needs to do. To counter that, cars have a cooling system.
If there is a fault in the cooling system, the temperature cannot be regulated and the engine just stays hot and heats up the nearby components as well. Consequently, the valve will get too hot and burn.
4. Cam timing is not in sync
Incorrect timing between the cam components can also burn the valve. When the crank and camshaft are misaligned, there will be too much friction between the two structures.
Increased friction will generate heat that is enough to burn and damage the valve.
5. Using LPG fuel
Although LPG fuel is an ideal choice for cars nowadays, it can sometimes take a toll on the valves.
LPG is a dry fuel and will clean the dirt from the engine parts. But because of all the cleaning, the lubrication will decrease in the valve seat and cause it to burn out.
Should You Ignore a Burnt Valve?
The valve is directly a part of the engine, which means it is a crucial component of the car.
When the valves are burnt, it will typically lead to your car using too much fuel than the required amount.
Continuing to drive with a burnt valve will slowly damage the other internal components of your car.
Eventually, your car will experience-
- Engine failure
- Costly repairs
- Poor performance
Regular cleaning and maintenance of the car might seem like a hassle, but it will save you a lot of money that will go into repairs.
So, once you notice any symptom of a burned valve, take your car to the mechanic and get it fixed as soon as possible.
How to Fix a Burnt Valve?
After diagnosing the symptoms and pinpointing the main issues, fixing the burnt valve may become easier.
Ultimately, you will need to repair or replace the valve completely. You can either get this done by a mechanic or by yourself if you are skilled enough with car parts.
Here’s what you can do to replace the valve by yourself, and the tools you will need:
Tools needed:
- Compression Gauge
- Thread Locker Screwdrivers
- Socket Wrench
- Drill (With Abrasive Wheel Attachment)
Step 1: Identify the faulty valve
Apply the compression gauge on each cylinder and check the value. If the compression value is below 145-150 PSI, then that valve is faulty and needs replacement.
Step 2: Remove the faulty valve
After finding the faulty valve, disconnect the spark plug wires. Then take off the valve cover of the faulty one.
Step 3: Extract the valve from the head gasket
Using a socket wrench, carefully unbolt the rocker’s arms. Then extract the valve from the head gasket.
Step 4: Check for faults
Clean up the dirt and debris from around the valve, and see if there is any warping. Take the drill machine and remove the carbon deposits, as this will create a new valve seal for the replacement.
Step 5: Install new valve
Take the new valve, and carefully place it in its position. Then secure it in place using a thread locker.
Step 6: Reattach everything else
After setting the new valve, reconnect the spark plugs. Then put the valve cover back on.
Step 7: Crosscheck with a car instruction manual
Check your car manual to see if any other related components need to be worked on. Follow the other relevant instructions in the manual and then start your car.
How to Prevent a Valve from Burning?
A valve replacement by a mechanic is very costly, so it is suggested you take measures to prevent the valve from burning. Here are some tips to follow:
- Use good quality fuel
- Maintain a substantial cooling system
- Take care out regularly for maintenance
Frequently Asked Questions (FAQs)
Can you clean valves with chemicals?
It is not a good idea to use chemicals to clean valves as the fluid can mix with the lubrication and generate heat and cause more damage.
Does a valve burn because of exhaust leaks?
Yes, a valve will burn due to exhaust leaks as it means the valve seal has not been set in properly, causing the leak and overheating.
What is the safe distance allowed to travel with burnt valves?
It is strongly advised to not continue driving with burnt valves, as it will quickly damage other internal components; hence, there is no safe distance allowed.
How much does it cost to replace a burnt valve in the US?
A skilled car mechanic will charge anywhere around $200 to $350 to replace a faulty valve.
Conclusion
A burnt valve can typically be caused by a mixing of combustion gases, lack of lubrication, and overheating of the engine. The repair costs can be high, so it is important to take the car regularly for maintenance.
So instead of letting your car’s performance go poorly, it is best to pinpoint the exact cause and then work on replacing the valve accordingly.
