Worn or damaged engine mounts allow excessive engine movement, which causes vibration in the cabin, clunking under acceleration and deceleration, and harsh shifts on automatic transmissions. They are wear items often overlooked until the symptoms become impossible to ignore. Replacement varies in difficulty depending on access.
What Engine Mounts Do
Engine mounts secure the engine to the chassis while isolating it from vibration. Most modern vehicles have 3 or 4 mounts: typically two on the sides supporting the weight, plus one or two torque mounts that resist engine rotation under load. Some are simple rubber blocks bonded between metal plates. Hydraulic mounts contain fluid for additional vibration damping. Active mounts use electronic actuators to vary stiffness based on engine RPM and conditions.
Symptoms of Worn Mounts
Excessive engine vibration through the steering wheel, pedals, and seats – especially at idle or in gear with the brake pressed. Clunking or thudding noises when accelerating from a stop, when releasing the throttle, or when shifting between drive and reverse. Visible engine movement when revving the engine in neutral with the bonnet open (a small amount is normal, but several centimetres of movement is excessive). Visible cracks, separation, or fluid leaks (on hydraulic mounts) when inspecting the mounts visually from below.
Inspection
Have an assistant put the vehicle in drive with the brake firmly pressed and gently apply the throttle while you watch the engine from underneath or from the side. Then have them shift to reverse and repeat. The engine should move slightly but not dramatically. Excessive movement (the engine rocking several centimetres or hitting other components) indicates one or more failed mounts. Visual inspection of each mount looks for cracked rubber, separation between the rubber and metal plates, or hydraulic fluid leaking from the mount body.
Replacement Procedure
Engine mount replacement varies enormously between vehicles. Some mounts are easily accessible from above with a few bolts. Others require supporting the engine with a hoist or jack and removing exhaust components, subframe bolts, or other items to access them. Always replace mounts one at a time so the engine remains supported. Never undo more than one mount at once unless you are using a proper engine support fixture.
Support the engine from above with a chain hoist or from below with a jack and a block of wood (to spread the load on the sump). Remove the bolts holding the mount to the chassis and the engine. Lift the old mount out, install the new one in the same orientation, and torque the bolts to specification. Lower the support and check engine alignment before driving.
Related Components
Transmission mounts are similar components that secure the gearbox to the chassis. They wear out at the same rate as engine mounts and should typically be replaced together. See our suspension bushings guide for related work since the underlying principle is the same.
Mount locations, torque specifications, and engine support requirements are vehicle-specific. MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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