My car shakes very bad whenever I’m accelerating or driving uphill…Could it be a motor mount or transmission issue?

Whenever I need to accelerate my car shakes very badly

My car has 100000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Motor and transaxle mounts, or an engine operating condition such as misfiring, are likely causes. A fault in the transmission is a less likely cause of the shaking that you are describing. Motor mounts fail due to separation or tearing of the rubber isolation components and/or failure of the internal hydraulic component if the mount is of the hydraulic type. Premature failure of mounts can occur due to abrupt acceleration occurring over a long period of time. Also, oil saturation of the rubber, from engine oil leaks, will cause early mount failure. To have this issue investigated and resolved, the recommended service is inspection/replacement of the motor mounts. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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If left undiagnosed, a broken motor mount will damage other engine or transmission components. The most common symptom of engine or transmission mount failure is a shudder upon acceleration. It is a vibration experienced by the driver.
Excessive Vibrations

The first obvious sign of bad motor mounts is; excessive engine vibration. Motor mounts are made to hold your engine in place and absorb vibration. If your engine is shaking in place, it`s probably a sign of bad motor mounts.

One of the most common engine mount symptoms is increased vibrations while using your vehicle. If you start your engine and notice that it is making more noise than usual and you can feel more vibrations than usual, this is a key sign of a worn engine mount that may need replacing.
Yes,in a manual car they can cause the transmission to slip out of gear,the same goes with the rear transmission mount !
The source of the problem could be from tires that are not balanced or a worn-out spark plug. It could also be loose lug nuts. A car also vibrates for a number of reasons when you accelerate. Typically it`s from a damaged inner CV joint.
The most likely cause of the shuddering most often happens in the vicinity of your car`s rims and tires. They plant your car to the road, and if anything is broken, will feel it. On a serious note, it may be a broken transmission mount or a broken caliper.
Engine Damage. In extreme cases, broken motor mounts can lead to engine damage. If your engine is given enough room to knock around, it can hit other components, causing damage to itself and other essential parts.
A failing motor mount can lead to serious engine damage and will also greatly impact the performance of the vehicle. It is very unsafe to drive with a broken motor mount. If you feel a lot of vibration in the vehicle while you are driving, there`s a good chance it`s the motor mount.
The most prevalent cause of vibration is problems with your wheels or tires. The potential problems include improper wheel and tire balance, uneven tire wear, separated tire tread, out of round tires, damaged wheels and even loose lug nuts.
Motor mounts keep your engine attached to the car. Weak or broken mounts can`t hold the engine tight in the engine compartment and creates a vibration at idle.
The most common reason for a car to shake is related to tires. If the tires are out of balance then the steering wheel can shake. This shaking starts at around 50-55 miles per hour (mph). It gets worse around 60 mph but starts to get better at high speeds.
Loose or damaged engine mounts may also be to blame if your car shakes when accelerating. As previously mentioned, damaged and loose engine mounts can`t efficiently absorb the vibrations produced by your cranking engine, so you`re likely to feel them when you step on the gas.
What are the Symptoms of Transmission Mount Failure? Excess vibration while the engine is running. Clanking or clunking noises when shifting gears. Transmission is difficult to put into gear or shift.
Motor mount replacement is a big job, though, so be wary of any mechanic or dealer that is offering to do the job for a price that seems too good to be true.
Engine movement & Misalignment

Also, if the mounts are bad which means the engine is not well aligned, will lead to engine sagging and drooping to one side.

Your motor mounts can be broken from the over-revving of gears, slamming the vehicle, and letting out the clutch or power-breaking before takeoff. This kind of driving can greatly reduce the life expectancy of your motor-mounts.
The most common symptom of the bad engine mount is engine vibrations felt on the steering wheel or seat when the car is in Drive. The radiator hose pulled out of the radiator due to the bad engine mount. The engine then lost most of the coolant and started to overheat.
For days, weeks, probably months. Most engine mounts have captive metal parts so the engine can`t drop out onto the road. It will just go clunk when you shift into drive or reverse. So it`s not a safety issue very much.
The most common reasons for your car to excessively vibrate are a problem with your tyres, wheels, brakes, steering, suspension, axle or engine.
This is a common symptom of a plug or wire electrical current problem. Air or Vacuum Hose – Another common cause for engine vibration and power loss is when air or vacuum hoses come loose, begin to leak, or rupture. The three necessities for all combustion engines are air, fuel, and spark.
Motor mounts: It`s the job of the motor and transmission mounts to dampen vibration. When they break, you`ll feel excessive vibration, especially at idle. You can diagnose this yourself by putting your car in neutral. If the shaking lessens, you very well could have broken mounts.
` Over time, the noise then starts to become an unmistakeable `clank` or `bang` before resulting in the failure of the mount or even worse – the engine. In summary, inferior or damaged engine mounts can cause vibration and damage, whilst replacing your engine mounts can eradicate all the above issues.
Oxygen (O2) sensor

An oxygen sensor monitors and analyzes the amount of oxygen in a vehicle`s exhaust system after combustion. A dirty, damaged or malfunctioning O2 sensor (or sensors) affects the air/fuel mixture, causing the engine to idle rough.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My car shakes very bad whenever I’m accelerating or driving uphill…Could it be a motor mount or transmission issue?
ANSWER : Motor and transaxle mounts, or an engine operating condition such as misfiring, are likely causes. A fault in the transmission is a less likely cause of the shaking that you are describing. Motor mounts fail due to separation or tearing of the rubber isolation components and/or failure of the internal hydraulic component if the mount is of the hydraulic type. Premature failure of mounts can occur due to abrupt acceleration occurring over a long period of time. Also, oil saturation of the rubber, from engine oil leaks, will cause early mount failure. To have this issue investigated and resolved, the recommended service is inspection/replacement of the motor mounts. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

2007 Nissan Altima motor mounts are new the motor vibrates a lot went the car is in drive with the ac on went I turn the ac off it
ANSWER : Hi there. It is possible that you have a vacuum leak or perhaps the transmission mounts are loose, as usually these symptoms are common with worn out motor mounts. When the AC is activated, it does create additional drag on the motor, which can make a small vibration even worse. It’s probably a good idea to have a professional mechanic come to your location and try and replicate the symptoms you are describing by completing a car is shaking or vibrating inspection.

When I’m driving, sometimes the car over revs and jerks when I shift gears after the cars been on for a while
ANSWER : Hi There,
What you are describing may be a result of a faulty speed sensor, potentially low transmission fluid or a even a faulty transmission control solenoid. As your vehicle travels down the road, the computer analyzes data being sent by vehicle speed sensors and engine speed sensors. Based on this information, the Engine Control Unit (ECU), or the Transmission Control Unit (TCM), executes the appropriate upshifts and downshifts by sending a signal to one of several shift solenoids. These transmission solenoids have spring-loaded plungers inside them, which are wrapped with wire. When this coil of wire receives an electrical charge from the TCM / ECU, it causes these plungers to open, allowing transmission fluid to flow into the valve body and pressurize the desired clutches and bands. When this happens, the transmission changes gears and you continue down the road. The computer controls the transmission solenoid in several ways. If the vehicle is equipped with a dedicated Transmission Control Unit, it can open or close the hydraulic circuit using a direct 12v signal. In some cases, the Engine Control Unit (ECU) can control the solenoid’s plunger by turning the ground circuit on and off. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your transmission.

Car jerks when accelerating in reverse & makes grinding noise. Is this a transmission or computer issue?
ANSWER : Hi there. Typically when you hear a grinding noise when you move forward or in reverse it’s usually an indication of a gear fault either in the transmission or another driveline component. If this occurs only when in reverse, it’s likely a damaged reverse gear. It is also possible that it’s a hydraulic fluid issue not supplying enough lubrication or pressure inside the lines to fully open the gear. I would recommend having a professional mechanic come to your location and complete a car is hard to shift inspection, so they can diagnose the source of your issue and recommend repairs that should resolve this problem.

2013 Ford Focus Transmission Issue. Is it worth keeping the car?
ANSWER : Hi There,
This is a known issue in this generation Ford Focus and some Fiestas with the "Power Shift" transmission and there have been numerous recalls and lawsuits. Although, it is would be difficult to determine how much longer your transmission will last given the fact that you have many new parts, I would not recommend junking the car as it may still provide some valuable life left for you. I would recommend taking it to the dealer to see if these parts may be covered under the recall.

Are the motor mounts touched during a tune up? When are the motor mounts touched?
ANSWER : There is nothing in a basic tune up that would require loosening or touching the motor mounts. If the motor mounts are in fact loose, they could potentially cause damage to the axles if the motor were to shift enough while driving; however, this would take time and there would have been a very distinct vibration and clunk that you would have very likely noticed while driving. I would recommend having a certified technician, such as one from YourMechanic, come take a look at the car to properly diagnose and repair your motor mount problem.

car shakes when idle and accelerating
ANSWER : It is very possible that you have a valve cover gasket or spark plug tube seal leak on your vehicle. These type of leaks will allow oil to leak onto the spark plugs causing misfires. When the engine misfires due to oil getting on the spark plug, the engine oil will burn. Since oil and tires are both petroleum products, they will both smell similar when they are burning. I would recommend having an oil leak inspection performed by a qualified professional to determine if there is an oil leak. Consider YourMechanic as an Oil/Fluid leak inspection can be peformed at your home or office.

My car shakes really bad when going over 40 mph
ANSWER : Hi there. From the description you have given, your vehicle shakes over 40 mph. The first thought would be the tires like you’ve mentioned. Typically vibration (shakes) are due to something that is out-of-balance. Given the tires and wheels have been balanced, it could be a wheel bearing vibration, as a worn, loose, or bad wheel bearing could cause shaking. It could also explain the noise getting louder as you accelerate.

This could also be an out-of-balance axle shaft, as worn cv joints (attached to each end of the axle shaft) typically creating a clack-clack-clack noise while turning. To get a precise diagnosis, you can get in touch with YourMechanic to inspect the noise in person and follow through with any repairs that are appropriate.