Motor (engine) mounts have no scheduled replacement interval — they’re replaced when they fail, which commonly happens somewhere between 80,000 and 150,000 miles depending on the vehicle, climate and driving, and the usual signs are increased vibration at idle, a clunk on starting or shifting, and an engine that visibly rocks when you rev it. The symptoms overlap with several guides on this site — notably car shakes at idle, car jerks when accelerating, and car shakes only when coming to a stop — and a worn mount is one of the most common root causes behind all three.
What Motor Mounts Do
Your engine and transmission are held in the car by a set of mounts — metal brackets bonded to rubber (or filled with fluid on some designs). They hold the heavy assembly in place while soaking up the engine’s vibration and torque reaction so it doesn’t reach the cabin. The rubber hardens, cracks and separates with age and heat; fluid-filled mounts can leak. When that happens, vibration and movement that were previously absorbed get through to the body.
Typical Lifespan
| Situation | Typical life |
|---|---|
| Normal driving, moderate climate | 80,000 – 150,000 miles |
| Hot climate, heavy stop-and-go use | Often at the shorter end |
| Fluid-filled (hydraulic) mounts | Can fail earlier, often with a leak or sudden vibration |
| Visible cracking, separation or fluid leaks | Replace now, regardless of mileage |
Warning Signs
- More vibration at idle, especially in Drive with your foot on the brake — see our car vibrates when idling in Drive but not in Park guide.
- A clunk or thump when starting the engine, shutting it off, or shifting between Drive and Reverse — see our car shudders when shifting from Park to Drive guide.
- A jerk or lurch when accelerating or lifting off the throttle.
- A shake as you slow to a stop — see our car shakes only when coming to a stop guide.
- Clunking over bumps in some cases, though suspension parts are more common culprits — see our clunking noise over bumps guide.
A Simple Check
- Look at the mounts with the hood open: cracked, split, collapsed or oil-soaked rubber is a clear sign.
- Have a helper shift between Drive and Reverse with the foot firmly on the brake while you watch the engine from a safe position — a healthy engine barely moves; a failed mount lets it lurch.
- Look for fluid on or under hydraulic mounts.
Never work under a vehicle supported only by a jack. Use axle stands on firm, level ground, chock the wheels that stay down, and leave the car in gear or Park with the handbrake on. A jack lifts; stands hold.
Can I Keep Driving With a Bad Motor Mount?
Short term, yes — it’s mostly a comfort and noise issue. But a badly failed mount lets the engine move enough to stress hoses, wiring, exhaust joints and the other mounts, so it’s worth fixing sooner rather than later.
When to See a Mechanic
When the symptoms above appear, or when you can see damage. Replacing mounts is usually a straightforward shop job; ask them to check the others while the engine is supported. More in our engine section.
Frequently Asked Questions
How often do motor mounts need to be replaced?
There’s no fixed interval; they’re replaced when they fail, which commonly happens between 80,000 and 150,000 miles depending on the vehicle and conditions.
What are the symptoms of a bad motor mount?
Increased vibration at idle, a clunk when starting or shifting, a lurch on acceleration, and an engine that visibly rocks when revved.
Can a bad motor mount cause a shake only when stopping?
Yes — the changing torque as the car slows to a stop is exactly when a worn mount shows its weakness.
Is it safe to drive with a broken motor mount?
In the short term, yes, but a badly failed mount can stress other parts and should be fixed soon.
How much does a motor mount cost to replace?
Typically $150–$500 per mount including labor, depending on the vehicle and mount type.
