Engine Knock on Startup then Goes Away (Causes & Solutions)

Is your car experiencing an engine knock on startup then Goes Away, and you don’t know why this is happening? Maybe you want to know how to prevent and protect your vehicle from knocking on startup.

This article will give you the correct information about car engine knock on startup and then goes away, its causes, and how to fix this problem. Read on!

There are a couple of reasons why your car engine knock on startup then goes away. First, if you start hearing the noise as you start the car, but as the car warms up, the noise gradually stops, you may not necessarily be so worried about your car engine.

These problems can be overwhelming when they occur and could make you panic when you don’t know what to do. We will dive into more details about these problems and even offer solutions to fix this issue.

Also Read: Car won’t start? Causes and How To Fix

Common Causes of Car Engine Knock on Startup Then Goes Away

Here are some of the causes of engine knock on startup then goes away.

1. Piston Slap

Piston slap is one of the causes of Car Engine Knock on Startup then Goes Away. When your car is old and gets to 180,000 miles, there’s a high tendency for piston slap issues to surface.

Piston slap is the loosening up of the piston from the cylinder wall when they are no longer adequately fitted together as they should be. Age is a factor in this because intolerance will increase as the component wears off.

This can alter the movement of the piston; instead of moving up and down, it will start moving in a rocky or shaky way.

This problem may result from the design flaw and not tear and wear in some cases. When that is the case redesigning can fix the problem.

Friction can create wear on the piston, leading to piston slap. This wear is primarily because of poor lubrication and maybe age.

Piston slap issues can be solved with the following steps.

1. Firstly, locate the engine by opening the engine bay. Get a mechanical toolbox and also get tools like screwdrivers and wrenches.
2. Then start dismantling the engine to gain access to the cylinders and pistons.
3. Take a very close look at the piston and walls of the cylinder. Check to see if there is a side-to-side movement or if the piston is inclined in any way. Ensure that the up and down movement is steady and there’s a tight tolerance.
4. Keep an eye out for wear and tear on the cylinder and piston.
5. If you notice the design is flawed too much and can’t be fixed by replacing the faulty component, you either carry out a piston-cylinder rebuild or call an expert to do it. Know that it is an expensive procedure and best done by an expert.
6. Assemble the engine, be careful not to forget to tighten and appropriately put back of components; when you are sure with these, check if the problem has been resolved.

2. Sticky Engine Lifter

If you check between your car valves and camshaft, you will see engine/valve lifters. Your car engine may knock on startup because of these lifters.

In addition, there’s a loud ticking sound distinct from other engine knocks, which is usually caused by a sticky engine lifter.

The most common cause of sticky valve lifters is poor oil lubrication. Hence, the sticky engine lifter problem will be solved if proper and good oil lubricant is used.

Furthermore, changing the oil when it is due for a change and adding protective additives can also solve this problem.

When your car has covered hundreds of miles, it may develop such a problem because the engine oil cannot control such gaps, leading to poor lubrication and mechanical fault that comes with an awkward sound.

Here are the steps to follow to identify and solve this issue:

1. Unlock and open the engine bay, then locate and examine the engine lifters with your eyes.
2. Take note of how long it takes for the engine knocks on startup to fade away because that will help ascertain why the engine lifters are faulty. Examine the component for signs of wear and tear because the part may have been affected by the prolonged noise.
3. Examine components like valve lifters, springs, and pushrods. Ensure that they are correctly fixed because they can cause sticky valve lifters if they have poor attachment and tolerances.
4. After examining the above and everything is in good condition, the problem is from the engine oil. Get proper engine oil with the right properties and viscosity suitable for your vehicle. Again, you can consult your car manual for assistance.

3. Worn Engine Parts

Engine knock on startup then Goes Away can happen because of worn-out engine parts. These engine parts can be alternators, steering pumps, and water pumps.

Your car will be functioning correctly until a particular part fails, at which point the check engine light will illuminate.

You will experience a rhythmical and harmonic noise from the worn engine part, but the noise will gradually die off as soon as your car starts up.

This is because the engine oil is circulating through the parts when the car is warmed up. The heat will help expand the bearing, and there will be a proper operation of the car irrespective of the wear.

Here are the steps to follow to identify and solve this issue:

1. First, check your check engine light to determine where the faulty component is.
2. Open the bay and carefully examine parts such as the exhaust manifold, valves, springs, and alternator.
3. Examine the parts and see if there’s poor lubrication and if the lubrication level is low because the engine part’s wear could result from your car leaking oil when parked.
4. Get a replacement for the worn-out parts and make sure there is good and enough engine part lubrication.

4. Bearing Worn-Out

The function of a bearing is to help rotational parts of the engine move properly. Without it, the engine won’t be able to work correctly.

For example, the engine will start producing sounds if they get worn out, causing the engine to knock on startup. Engine slap can also happen as a result of worn-out bearing.

The main crankshaft bearing is the most affected, causing a disconnection between the crankshaft and other engine parts.

When the crankshaft is heated, the issue disappears and resurfaces when the temperature drops.

Here are the steps to follow to identify and solve this issue:

1. Open the engine bay and examine the bearing and crankshaft.
2. Inspect the bearings for wear and crankshaft tolerances for deviations.
3. Check the oil conditions of the bearing, and ensure that it’s okay because poor bearing lubrication can lead to bearing failure.

5. Oil Drain-Back

Another reason why your car engine knocks on startup then goes away is oil drain back. It is possible that your engine oil is not properly sealed when your engine block drains oil through the check valve.

If your check valve is faulty, the engine block won’t be properly sealed, allowing oil to leak from the oil filter.

In this case, the oil pump is forced to pump oil into sensitive parts that are not designed to handle oil. As a result, you will keep hearing the knocking sound for a minute till the oil is pushed into the engine parts and thoroughly lubricate the parts.

Though this problem will disappear after the engine is warmed up, the sound issue will still surface on startup.

Here are the steps to follow to identify and solve this issue:

1. Immediately after opening the engine bay, check the oil filter.
2. Examine the check valve to ensure it is securely fitted.
3. When you notice oil on sensitive parts where oil shouldn’t be, it’s a clear sign of an oil drain back problem.
4. Buy and replace the oil filter to protect the oil in the engine block. Ensure that you purchase the original oil filter with quality check valves. Don’t buy cheap oil filters since they won’t last and don’t have quality check valves.

6. Carbon Buildup on Engine

As your car starts getting old, it starts building up carbon in the engine. This is because the engine no longer performs complete combustion, producing black soot.

This buildup will cause the hardening of the engine parts, which is very unhealthy for your engine. This can cause engine knock on startup then Goes Away and even difficulty starting.

However, the knocking sound will go away as soon as the oil circulates and the engine is completely lubricated.

Here are the steps to follow to identify and solve this issue:

1. When you notice that your car engine oil is dirty, it indicates that there is lots of buildup and dirt in your car engine, resulting in performance problems.
2. Remove and replace the oil filter and the oil with a new one if the oil is dirty.
3. Loose and clean the engine, removing all forms of carbon deposit from the engine part with a solvent. You can use steel wool to soak the engine parts for 15minutes. It will assist in removing the dirt.
4. Assemble the engine parts appropriately.

How Much Does It Cost to Fix Engine Knock on Startup Then Goes Away?

Before we talk about the cost of fixing an engine knock on startup then Goes Away, we should know that there are factors that influence this cost.

Such factors include but are not limited to the price of parts, location, labor cost, price of buying and changing oil, and flaws associated with design.

The cost of fixing engine knock on startup then Goes Away is quite expensive, and it could be as low as $2,000 or more or as high as $5,000 or more. The cost of cleaning the engine can range from $250-$500.

Also Read: Oil on Spark Plug Threads (Causes & Solutions)

How to Prevent Engine Knock on Startup That Goes Away

As earlier stated, engine knock-on startup that goes away can be caused by a couple of reasons, such as wear and tear of engine components or piston slap.

When you notice such symptoms, please ensure to visit your mechanic for proper diagnosis because if you allow the problem to persist, you are signing in for a bigger problem. The earlier you resolve the issue, the better.

Below are suggestions on how to prevent your car from experiencing engine knock on startup then Goes Away.

1. Use Good Quality Engine Oil

When you use quality engine oil with suitable viscosity for your car, it will help reduce and even prevent the wear of engine components.

As your vehicle gets hot, the engine components expand, creating fractions, and if the engine doesn’t have proper lubrication, the car will be at the risk of engine damage.

To increase the life span of the engine components, use oil additives; this will help in reducing the heat generated by the engine and keeping the engine part well lubricated.

To clean up engine wear particles, diesel engine additives are suitable; they can also remove carbon deposits from engine components and stop engine knock-on startup, improving fuel economy and general living conditions of the engine.

Don’t forget to check your car manual to know the exact oil viscosity and oil components suitable for your car. Consult a car professional if you can’t get hold of your manual.

2. Get Your Engines Tuned Regularly

To avoid misfire, carbon buildups hiccups, and the prevention of engine knock-on startup, schedule a proper engine turning regularly with an engine turning expert.

This is because an engine expert knows and understands engine behavior and can diagnose a problem more effectively.

Carrying out engine turning regularly will help enhance your vehicle’s fuel economy and increase the overall quality of your car performance. This is accomplished by making necessary adjustments to the engine components.

3. Replace the Oil Filter on a Regular Basis

Your engine oil may become dirty due to a dirty engine and faulty filter. Hence carrying out regular filter changes is very important.

This is to avoid sludge buildup and poor lubrication of the engine components, which can affect the working conditions and performance of the engine.

Therefore to ensure efficient engine performance and avoid engine knock on startup then Goes Away or other related problems, always carry out regular filter changes.

4. Avoid Driving Rough

Driving rough or aggressively can also affect the working condition of your engine. This is because it can lead to deterioration of the engine components, resulting in piston slap and engine knock on startup then Goes Away.

5. Never Ignore Check Engine Light

Your check engine light is your first contact with the engine or even other parts of your car, this is because you cannot know what is happening to your car components as you drive, but with the help of your check engine light, you will know when something is wrong with your car.

Therefore whenever the check engine light comes up, never ignore it because if you do, you will be creating more problems and damage to your vehicle. See a mechanic as soon as possible when your check engine light comes on.

Frequently Asked Questions – Engine Knock on Startup That Goes Away

Conclusion

This article has provided information on what is engine knock on startup and goes away. In addition, we have been able to list the causes of this problem and offer solutions to deal with it.

The most frequent causes of engine knock on startup then Goes Away are carbon buildup, sticky lifter, worn-out bearing piston slap, and worn-out engine parts.

The best approach is to carry out regular maintenance to help adjust engine components when necessary, clean up soot and dirt, and give a general healthy working condition in your car engine to prevent this problem from occurring.

When the signs persist after you have done all required to prevent engine knock on startup, as stated in this article, please consult an expert to examine your car engine.