Pushrods are used in overhead valve engines, and their main function is to transmit the reciprocating motion that allows the internal combustion engine to work optimally. A cam usually actuates pushrods for the opening and closing of an internal combustion engine.
This article will outline bent pushrod symptoms. If you have a car that uses an overhead valve engine, you’re most likely to encounter bent pushrod issues at least once. That’s why this article tends to outline bent pushrod causes and symptoms.
A pushrod is a cylindrical rod in an overhead valve engine operated by a camshaft that opens and closes valves. Both ends of a pushrod have openings that help in sending and receiving oil to the rocker arms.
The rocker arm is another component that plays a vital role in internal combustion engines. Rocker arms work hand in hand with the pushrods.
What Is a Pushrod?
It is a part of the internal combustion engine. This unique part is found in a pushrod or overhead valve engine.
The camshaft is found in the block near the crankshaft, but the valves are normally found in the cylinder head.
A valve lifter rides on the cam. When the cam lobe comes in contact with the lifter, it rises and then transfers the motion to the pushrod. This action then moves a rocker, which in turn pushes the valve open.
The pushrod is also hollow. So, it helps channel oil from the lifter and through and out the rocker arm. The oil is necessary for lubricating the rocker arm and cooling the valve spring.
The pushrod is responsible for squarely centering the rocker arm over the valve tip. So, a bent pushrod could affect the performance of the rocker arm.
What Do Pushrods Do In a Car?
A camshaft in an engine converts rotational motion into linear motion, which the valves use to open and close to permit fuel and air into the combustion chamber.
Components of a traditional OHV engine valvetrain by IJB TA / CC BY-SA 3.0. Rocker’s arms are used in OHC engines instead of pushrods, which is the distinction between OHV pushrod systems and OHC engines.
One or more camshafts and pushrods operate in concert to move the rocker arms, which pivot and actuate valve stems, to accomplish this.
There are two such systems, one for opening the valves and the other for closing them, on each cylinder.
These are controlled by camshaft lobes, which at specific points throughout each engine cycle convert this circular motion into up-and-down or back-and-forth movement.
“Up” in most engines refers to the direction of the valves, which are found at the top of the cylinder head.
An intricate camshaft position sensor mechanism is employed in some older systems. To determine each lobe’s precise role throughout each engine cycle, this system must account for the variable height of each lobe.
The majority of engines built from the early 20th century to the present day have overhead valve (or OHV) engine designs, in which one or more camshafts and pushrods control the valves.
Together, these parts move the valves up and down in sync with the rocker’s arms so that air and fuel enter the combustion chamber at precisely timed intervals.
How Pushrods Work?
An engine (or more specifically, the camshaft) transfers rotational motion into linear motion of the valves which open and close to let air and fuel into the combustion chamber.
This is achieved with a combination of one or more camshafts and pushrods that work together in unison to move the rocker arms which pivot and actuate valve stems.
Each cylinder has two such systems: one for opening valves, another for closing them. These are operated by lobes on the camshaft, which translate this circular motion into up-and-down or back-and-forth action at appropriate times during each engine cycle.
In most engines, “up” means toward the top of the cylinder head, where the valves are located.
In some older systems, a more complicated camshaft position sensing system is used. This system must take into account the varying height of each lobe to determine its specific function during each engine cycle.
In an overhead valve (or OHV) engine design – which includes most engines produced from the early 20th century until today – valves are operated by one or more camshafts and pushrods.
These components work together in unison with rocker arms to move the valves up and down to let air and fuel into the combustion chamber at precisely timed intervals.
Bent Pushrod Symptoms
Many symptoms can indicate that a pushrod is bent. These include:
- Engine Misfires
- Rough Idling
- Ticking Noise
- Poor Performance and Acceleration
- Failed Compression Test
- Increased Emissions
Let us discuss these symptoms in a bit detail:
#1. Engine Misfires.
An engine misfire is one of the most common symptoms of a bent pushrod. The misfire can be caused by a number of factors, but the most likely cause is that the pushrod is not opening the valve correctly.
This can cause the air/fuel mixture to enter the cylinder at the wrong time, which will result in an engine misfire.
Other possible causes of an engine misfire include a faulty spark plug, ignition system, or fuel injector. However, if you have ruled out all of these other potential causes, then it is likely that the pushrod is to blame.
#2. Rough Idling.
Another symptom of a bent pushrod is rough idling. This is because the pushrod is not opening and closing the valves correctly, which can cause the engine to run poorly. The engine may also stall or have difficulty starting if the pushrod is bent.
#3. Ticking Noise.
A bent pushrod can also cause a ticking noise from the engine. Two things usually cause pushrod noise: the pushrod itself is damaged, or the rocker arms are worn out. If the pushrod itself is bent, it can cause the engine to run roughly and make a knocking sound.
Alternatively, if the rocker arms are worn out, they may not be able to properly actuate the valves, resulting in valvetrain noise. In either case, it is important to have a qualified mechanic check your engine to determine the root cause of the noise.
#4. Poor Performance and Acceleration.
Another symptom of a bent pushrod is poor performance and acceleration. This is because the engine cannot breathe properly, which can lead to a loss of power. The engine may also hesitate or stall when you try to accelerate.
Bent pushrod causes poor performance and acceleration because it can not transfer the correct amount of force from the cam to the valve. This can lead to valves not opening or closing fully or at the right time.
As a result, the air/fuel mixture may enter or exit the combustion chamber at the wrong time, affecting engine performance and power.
#5. Failed Compression Test.
One of the most common causes of low engine compression is bent pushrods. When pushrods are bent, they can no longer properly transfer the force from the camshaft to the valves.
This can result in the valves not opening all the way, which decreases the amount of air and fuel that can enter the combustion chamber. As a result, the engine’s compression ratio is lowered, and it may not be able to generate enough power to run properly.
If your engine is producing low compression on one or more cylinders, it’s possible that a bent pushrod is to blame.
You can perform a compression test to check for this issue. If the readings are low on one side of the engine, it indicates that a bent pushrod is causing the problem.
#6. Increased Emissions.
Bent pushrods can also cause increased emissions from the engine. This is because the air/fuel mixture is not burning correctly, leading to unburned fuel being expelled through the exhaust system.
If you notice that your vehicle’s emissions are higher than normal, it’s possible that a bent pushrod is to blame.
What Causes a Bent Pushrod?
#1. Normal Wear and Tear.
Several variables, including wear and strain, can result in pushrods in an engine system bending.
The metal parts merely rubbing against each other over time, generating heat and friction, is the most frequent reason. This may eventually cause the metal to deform or even break.
Additionally, regular engine cycling (starting and stopping) can strain the pushrods, which over time may result in bending. Pushrod bending can also be caused by improper installation or engine care (such as infrequent oil changes).
#2. Unsecured Valve Guides.
One or more potential causes of bent pushrods in an overhead valve engine include loose valve guides or broken valve springs.
The valves may move more freely than they should if the valve guides are unfastened. This may disrupt the rocker’s arm motion and cause the valves to move irregularly.
Since the pushrods and rockers’ arms are joined directly, any irregularity in the rockers’ motion might cause the pushrods to bend.
Pushrods’ length as hollow metal tubes should be taken into account as well because even a small force applied across their longitudinal axis might cause them to bend.
#3. Overheated Engine.
Pushrods in overhead valve engines may bend due to overheating’s effect on the metal’s expansion. This may result in the pushrods going out of alignment, which may result in the engine misfiring or knocking. This can eventually harm the engine if ignored.
Maintaining a full tank of engine coolant and never letting the engine become too hot will help you avoid this. If you suspect that your engine is beginning to overheat, stop immediately and turn it off.
#4. Hydraulic Lifters That Stick.
Sticking hydraulic lifters is another factor that could lead to bent pushrods. Some engines employ hydraulic lifters to operate the valves. They function by modifying the space between the valve and the rocker arm by use of oil pressure.
However, if they get trapped, they might exert too much pressure on the valves, which might bend the pushrods. Additionally, broken valves and misfired engines might result from this.
#5. Unstable Rocker Arm.
As is common knowledge, the pushrods in an overhead valve engine are in charge of transmitting the camshaft’s motion to the valves. The valves are opened and closed by a lever created by the rocker arms, which are positioned on top of the pushrods.
A rocker’s arm may start to bounce up and down on the pushrod if it becomes loose. The pushrod may eventually bend as a result of this continuous action.
Poor engine performance results from the pushrod being bent since it can no longer effectively transmit the camshaft’s motion to the valves.
#6. Unintentional Damage.
Another potential explanation for bent pushrods is accidental damage. This may occur if the engine is dropped or struck so forcefully that the pushrods bend.
Another scenario is when a foreign object, such as a piece of trash, enters the engine and strikes the pushrods. It is preferable to take your engine to a mechanic for inspection if you suspect that it has been damaged.
#7. A Bad Installation.
One of the most prevalent reasons for bent pushrods is improper installation. One way is by not tightening the rocker’s arms down enough. The pushrods may be subjected to excessive force and flex if the rocker’s arms are not correctly torqued down.
Using pushrods that are simply too weak for the application is another frequent reason. It’s crucial to use pushrods that are adequate for the job because weaker materials are more likely to bow under heavy loads and pressures.
How to Replace a Bent Pushrod?
Replacing bent push rods needs to be done with precision and care. Failure to correctly replace these engine components can lead to additional engine damage and increased repair costs.
This section will provide a general guideline on how to replace bent push rods. If you don’t possess the know-how to access and remove the push rods, you should hire a professional mechanic.
Gather Necessary Tools and Parts
These typically include a socket set, wrenches, torque wrench, screwdrivers, and of course, new push rods compatible with your engine.
Make sure to consult your car’s manual for any specific tools required. Having everything at hand will streamline the replacement process, minimizing downtime and potential errors.
Safety First
Make sure the car is parked on a level surface, and the engine has cooled down. Disconnect the battery to prevent accidental electrical shorts.
Wearing safety gloves and goggles is highly recommended as you’ll be dealing with various engine components that could be hot, sharp, or greasy.
Replace a Bent Pushrod Step By Step
#1. Remove Engine Components for Access.
To get to the push rods, you’ll usually need to remove some engine components, such as the air filter, intake manifold, or valve covers, depending on your specific vehicle.
Use your socket set and wrenches to carefully take off these components, remembering to keep all screws and bolts organized for reassembly.
#2. Locate and Assess the Bent Push Rods.
With the engine components removed, you should have a clear view of the push rods. Inspect each one to identify which are bent.
Bent push rods can often be visually spotted, but in some cases, you may need to remove them for a more detailed inspection. Keep track of the location of each bent push rod; this is essential for the reinstallation process.
#3. Remove the Bent Push Rods.
To remove the bent push rods, you’ll generally need to loosen the rocker arms that sit atop them. Once the rocker arms are loosened, carefully lift them off and set them aside.
After that, you can pull out the bent push rods. Some might require a bit more effort to remove, especially if they are severely bent.
#4. Prepare the New Push Rods.
Before installing the new push rods, it’s a good idea to lubricate them lightly with engine oil. This helps in reducing friction during the initial startup after replacement, ensuring that the new push rods can operate smoothly.
#5. Install the New Push Rods.
To install the new push rods, simply reverse the removal process. Insert each new push rod into its respective slot.
Make sure they are positioned correctly, sitting well within the lifter and making proper contact with the rocker arms. Re-tighten the rocker arms, adhering to the torque specifications provided in your vehicle’s manual.
#6. Reassemble the Engine Components.
Once the new push rods are securely in place, you can start reassembling the engine components that were removed earlier. Make sure to tighten all screws, bolts, and clamps securely, and double-check to ensure you haven’t missed anything.
#7. Reconnect the Battery and Test.
After everything is reassembled, reconnect the car battery. Start the engine and listen carefully for any abnormal sounds that might indicate a problem. If everything sounds normal, take the car for a test drive to ensure it’s operating correctly.
How To Prevent This Problem?
There are a number of things you can do to prevent a pushrod from being bent:
Change the engine oil timely
Changing your engine oil is mandatory to avoid friction between the metal parts of a car. If the engine is kept lubricated, the metal-to-metal contact is reduced, and the push rods will also avoid too much friction and not be bent over time.
Reduce the engine vibrations
Vibrations in cars can become one of the leading causes of a bent pushrod. This can be done by using balanced weights on the car, installing engine mounts, and adding damping material to the bay of the engine.
Go for high-quality pushrods
Pushrods are fairly inexpensive compared to other automobile parts. So if you are purchasing new ones to replace any damaged rods, make sure to purchase the best one available. The ones with better quality will ensure that it doesn’t break under pressure.
Make sure to install the pushrods correctly
Installing a pushrod in a car makes sure that it will not get bent or damaged if they are under any excess pressure. The rods should also stay in place to help in the opening and closing of the valves in the engine.
Avoid excessive stress on the rods
Try not to put too much pressure on the pushrods by avoiding hard starts and sudden stops. This helps not to overload the engine and keep the rods intact for longer.
These are just safety measures that can help you out with the care of your car components without seeking professional help every time.
How Much Does It Cost to Fix Bent Pushrod Symptoms?
Your car’s pushrod will need to be replaced if it is bent. Depending on the make and model of your car as well as the extent of the damage, the price of this replacement will change.
One of the trickiest maintenance jobs on an internal combustion engine is swapping out a faulty pushrod. Since it includes disassembling and reassembling some of the most important parts of your car’s engine, this replacement task is highly difficult.
A bent pushrod replacement typically costs between $800 and $1,200. If extensive damage necessitates additional parts or repairs, this repair may even be more expensive.
Between $350 and $550 can be spent on a complete push rod replacement kit that contains all necessary parts, including guide plates, rocker arms, pins, valve cover gaskets, and seals. If the current valve cover is harmed, you might also need to get a new one.
It takes a professional mechanic six to eight hours to replace a bent pushrod. Therefore, the price of labor will range from $480 to $960. Only a skilled mechanic should try to complete this challenging repair.
The right tools and equipment for the job are also crucial. It’s crucial to thoroughly read all instructions and take your time if you try to fix this yourself. Your engine could sustain serious damage if you make a mistake.
FAQs.
Q: Can you straighten a bent pushrod rod?
Yes, you can straighten a bent pushrod. Grab your bent pushrod and place it on your vice or a cement driveway and straighten it with a hammer. I recommend getting a new one. You can straighten the old Pushrod only if you don’t have some cash to replace them.
The bigger challenge is knowing what bends your pushrod and fixing it at the same time. If not, it may cause a bigger problem.
Q: Can you drive a car with a bent pushrod?
You can drive with a slightly bent pushrod. Bent Pushrod will only cause your car to reduce power, have a ticking sound, and fail the compression test. However, it is recommended to diagnose and replace the bent pushrod once you notice any of these symptoms.
Final Words
We have discussed bent pushrod symptoms at length. It’s important to know that there are factors that can prevent sticking sounds in your engine. As we know, these sticking sounds indicate a worn-out valve or bent pushrod.
A frequent oil change with the recommended oil grade for your engine will help reduce the number of studs and sludge in your engine. A sludge-free engine will allow for good sliding of your pushrods.