What Are Engine Mounts?
Engine mounts (also called motor mounts) are the brackets and rubber cushions that attach the engine — and usually the gearbox — to the vehicle's chassis or subframe. They serve two critical functions:
- Support the engine's weight and hold it in position
- Isolate engine vibration from the cabin — preventing every firing event from being felt through the car
Most vehicles have two to four engine mounts, plus a separate transmission (gearbox) mount. Each mount typically consists of a metal bracket bonded to a rubber cushion, which absorbs the engine's movement and vibration.
Some modern vehicles use hydraulic mounts (filled with fluid) for superior vibration isolation, particularly common on European and some Japanese vehicles.
Signs of Worn or Failed Engine Mounts
Excessive Vibration at Idle
This is the most common sign. If you feel unusual shaking or vibration in the cabin when the engine is idling — particularly at a stop with the car in gear — worn engine mounts are a likely cause.
Healthy mounts absorb most vibration. Worn ones transmit it directly to the chassis and cabin. The vibration often feels worse:
- At cold idle (before the engine warms up)
- In gear with the brakes applied (like at traffic lights)
- With the A/C running (extra engine load)
Clunking on Acceleration or Gear Changes
A clunk or thump felt when:
- Accelerating hard from a standstill
- Changing from drive to reverse (or vice versa)
- Lifting off the throttle abruptly
This is the engine moving excessively in its bay. Worn mounts allow more movement than intended, and when the engine torques against the mount, it transfers that impact to the chassis as a clunk.
Engine Moving Visibly in the Bay
In severe cases, you can see the engine rocking or moving when someone revs it in the engine bay (engine off is safer — do this check carefully with a helper). Normal engines move slightly; worn mounts allow significant rocking.
Vibration Through the Steering Wheel or Gear Lever
Engine vibration transmitted through the chassis can be felt in the steering wheel or gear lever, particularly at idle.
Knocking on Speed Humps
If the engine is sitting too low due to a collapsed mount, it may contact the subframe or other components when the car goes over speed bumps — producing a solid knock from the engine bay.
Misaligned Components
Severe mount failure allows the engine to shift position, potentially causing:
- Drive shafts or CV axles to run at extreme angles
- Coolant hoses to stretch or kink
- Exhaust contact with body panels
Hydraulic Mount Failure
Hydraulic mounts develop internal leaks, causing the fluid to drain. Signs of hydraulic mount failure:
- Sudden increase in idle vibration
- A leaking or wet appearance on the mount itself (fluid seeps out)
- Often these fail more dramatically than rubber mounts
WoF Relevance
Engine mount condition is inspected during a WoF check. Specifically:
- Collapsed or severely deteriorated mounts are a WoF failure
- An engine that has shifted significantly due to failed mounts may cause other inspectable components (CV axles, drive belts) to be at risk
- Inspectors look for cracked, torn, or collapsed rubber
NZ Cost to Replace
| Job | Typical NZ Price |
|---|---|
| Single engine mount (standard rubber) | $200–$450 |
| Full engine mount set (2–3 mounts) | $500–$900 |
| Transmission/gearbox mount | $200–$400 |
| Hydraulic engine mount (e.g., VW, Mazda) | $350–$700 each |
| Complete engine and transmission mount service | $600–$1,400 |
Prices vary significantly by vehicle. European vehicles with hydraulic mounts are at the expensive end. Japanese-spec vehicles (Toyota, Honda, Mazda) are typically more affordable and well-supported by the aftermarket in NZ.
How Long Do Engine Mounts Last?
Rubber mounts typically last 100,000–180,000 km, though NZ conditions can reduce this:
- High-mileage Japanese imports often have original mounts well past their best
- Vehicles used for towing experience faster mount deterioration
- Vehicles with modified engines (louder, more vibration) wear mounts faster
When to Book a Mechanic
- Vibration through the car at idle that wasn't there previously
- Clunking when you first apply throttle or change from reverse to drive
- A solid knock from the engine bay over speed humps
- Pre-purchase inspection on a high-km vehicle — engine mount condition is worth checking
Engine mounts are a relatively inexpensive preventive repair that significantly improves the driving experience and prevents more expensive secondary damage from an engine that's moved too far in the bay.