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Signs Your Motor Mounts Are Failing

Stephen Fogel
March 30, 2018

Your car’s motor mounts serve two important purposes. They attach the engine to the chassis, keeping the engine in place, and they dampen its vibrations so that you don’t feel them while you drive. 

When they start to go bad, things can get dangerous. Here's what to look out for.

Symptoms of bad motor mounts

1. Odd noises from under the hood: When your motor mounts deteriorate, you may start hearing a variety of noises as you idle, accelerate and brake. These sounds are caused by the engine moving around excessively and smacking other items under the hood. These noises can include thumping, clunking, rattling and clanging. If you hear suspicious noises, see your mechanic right away.

2. Excessive engine vibrations: As the soft parts of the motor mounts wear out, they lose their ability to both absorb vibrations and keep the engine stable. The motor can now move around more than it should. You may feel the entire vehicle vibrate during starting, when idling, during heavy acceleration, or some combination thereof. You’ll want to get them checked out.

3. Your engine looks out of alignment: Good motor mounts keep your engine aligned with all the other components around it. Bad or failed motor mounts can sometimes be detected by the way your engine sits. Does it appear to be tilted? Is it sagging from side to side, or front to rear? This could be a sign of a major motor mount problem; have it looked at immediately.

4. You have broken engine hoses and belts: If your engine is moves around, it puts a huge amount of stress on parts like your coolant hoses. These run from the engine to the radiator, which is rigidly attached to the chassis. Excessive engine movement can tear or break off these hoses, likely leading to coolant loss — and a blown engine, if you don’t catch it immediately.

Engine-mounted belts that run items like your power steering pump and water pump can also be damaged or broken by an engine that is loose on or unattached to its mounts. Damage to these belts can affect the operation of your steering or cooling systems, both with very bad consequences. 

5. Your engine shows external damage: This can happen in extreme cases, when your motor mounts are so far gone that they are no longer attached to your engine. The engine can now move freely under the hood, banging around and damaging the parts of the engine that make contact. An engine-driven fan can hit the radiator. An exhaust manifold can crack or break where it meets the exhaust pipe. Front-wheel drive cars can suffer CV joint or halfshaft damage from the motion of the engine. Parts can also fly off from these impacts, causing additional mayhem. 

Because this often happens during hard acceleration or high-speed driving, the potential for a life-threatening situation here is high. If you notice these conditions, it is unsafe to drive.

Get it diagnosed by a professional
 

What are motor mounts?

Your motor mounts are made of both hard metal and soft rubber or polyurethane. Over time, the soft parts can deteriorate due to wear from lots of miles driven, or from exposure to heat and fluids under the hood. Some types of motor mounts are hydraulic, with fluid-filled chambers that can leak and become less effective. In extreme cases, the hard metal parts can bend, crack or even break off.

Failing motor mounts will hurt the stability and smoothness of your engine, and can cause damage to other crucial parts of your car. 

» MORE: Get an accurate estimate for your car repair

What to do about bad motor mounts

If you check the motor mounts, look for brackets that are broken, cracked or loose; missing or loose bolts; cracks and tears in the rubber parts; fluid leaks or collapsed rubber parts in hydraulic-type motor mounts; and a general sagging or off-center appearance.

Bad or failing motor mounts cannot be repaired. They are simply replaced with new ones. This job is best left to a professional mechanic, as the engine will need to be supported from above while the mount is replaced. Other components like exhaust gaskets or radiator hoses may also need to be swapped out if they’ve been damaged.

Check your car’s warranty booklet to see if motor mounts are covered as part of your powertrain warranty. This could save you from the cost of a potentially expensive repair.

 

Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

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