🔧 340i - Engine Mount Replacement

Engine mounts are rubber-and-fluid isolators that hold the engine in place and absorb vibration. When they collapse or leak, you may feel shaking at idle, clunks on throttle changes, or extra drivetrain movement.

Difficulty Level: Advanced | Estimated Time: 3-6 hours

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⚠️ Safety & Precautions

• ⚠️ Support the engine before removing any mount fasteners.
• ⚠️ Never get under the car supported only by a jack; use jack stands.
• ⚠️ Let the engine cool fully; turbo/exhaust areas can burn you.
• ⚠️ If you use a floor jack on the oil pan, always use a wide wood block to spread the load.
• ⚠️ Many BMW mount bolts are “torque-to-yield” (one-time-use); replace the mounting bolts/nuts you remove.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Engine support bar (specialty)
• Wood block (2x6 in. minimum)
• Safety glasses
• Mechanic gloves
• Torque wrench (10-200 Nm range)
• Ratchet (3/8 in.)
• Ratchet (1/2 in.)
• Socket extension set (3/8 in. drive)
• Universal joint adapter (3/8 in.)
• Torx T25 screwdriver
• Torx T30 screwdriver
• E-Torx socket set (E10, E12, E14)
• 16mm socket
• 18mm socket
• Trim clip removal tool
• Flashlight
• Paint marker

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Left engine mount - Qty: 1
• Right engine mount - Qty: 1
• Engine mount bolt/nut kit (one-time-use hardware) - Qty: 1
• Lower engine splash shield fastener clips (as needed) - Qty: 1

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📋 Before You Begin

• 🅿️ Park on level ground, set the parking brake, and chock the rear wheels.
• 🧰 Plan your support method: an engine support bar holds the engine from above using the strut towers (best and safest for this job).
• 🔋 Battery disconnect is not typically required for mounts, but keep the key away from the car so the cooling fan can’t start unexpectedly.
• 📝 Assumption: stock intake/undertrays and factory-style mounts; bolt sizes vary slightly by production date.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise and secure the car

• Use a floor jack (3-ton) at the front center jacking point, then set the car on jack stands (3-ton) at the front jack pads.
• Use wheel chocks behind both rear wheels.

Step 2: Remove the lower splash shield (undertray)

• Use a Torx T25 screwdriver and Torx T30 screwdriver to remove the undertray screws.
• Use a trim clip removal tool to pop any plastic clips without breaking them.
• Use a flashlight to confirm you can see both engine mounts and their fasteners.

Step 3: Support the engine

• Install the engine support bar (specialty) across the strut towers and attach the hook/chain to a solid engine lifting point.
• Take up the slack until the engine just begins to “feel supported.”
• Do not lift high; just relieve mount load.

Step 4: Identify and mark mount positions

• Use a flashlight to locate the left and right mounts (one per side between engine bracket and subframe).
• Use a paint marker to mark the mount-to-subframe bolt locations so you can reinstall aligned.

Step 5: Loosen the mount-to-subframe fasteners (do not remove yet)

• Use an E-Torx socket (E12/E14 as equipped) with a ratchet (1/2 in.) and socket extensions to crack loose the mount-to-subframe bolts.
• If access is tight, use a universal joint adapter (3/8 in.) with a ratchet (3/8 in.).

Step 6: Loosen the mount-to-engine bracket nuts/bolts

• From below, use a 16mm socket (common) or 18mm socket (some variants) with a ratchet and extensions to loosen the top mount fasteners.
• Only loosen at first; you want the engine still guided by the mounts.

Step 7: Lift the engine slightly for clearance

• Use the engine support bar (specialty) adjuster to lift the engine just enough to remove each mount.
• Watch for anything stretching: hoses, wiring, and the intake ducting.
• Small lift is usually enough.

Step 8: Remove the right engine mount

• Use an E-Torx socket (E12/E14) to remove the mount-to-subframe bolts.
• Use a 16mm socket or 18mm socket to remove the mount-to-engine bracket fasteners.
• Work the mount out carefully; rotate it to clear nearby lines.

Step 9: Install the new right engine mount (start all fasteners by hand)

• Position the new mount in the same orientation as the old one.
• Start the mount-to-engine bracket fasteners by hand (use a 16mm socket or 18mm socket to snug only).
• Start the mount-to-subframe bolts by hand (use an E-Torx socket to snug only).
• Hand-starting prevents cross-threading.

Step 10: Remove and replace the left engine mount

• Repeat Steps 8-9 on the left side using the same tools: E-Torx sockets, 16mm socket/18mm socket, and extensions.
• Adjust the engine support bar (specialty) slightly as needed to create clearance.

Step 11: Set engine weight back onto the mounts

• Slowly lower tension on the engine support bar (specialty) until the engine rests naturally on both new mounts.
• Make sure the mount studs/holes sit centered and not “pulled sideways.”

Step 12: Torque all mount fasteners

• Use a torque wrench (10-200 Nm) to torque fasteners.
• Important: BMW commonly uses one-time-use aluminum bolts and torque-angle specs here; torque values depend on the exact bolt set installed.
• Torque guidance (most common for this platform):
  • Mount-to-subframe bolts (often M12): Torque to 100 Nm (74 ft-lbs) + 90°
  • Mount-to-engine bracket fasteners (often M10): Torque to 55 Nm (41 ft-lbs) + 90°
• If your replacement hardware kit specifies different values, follow the kit/OEM spec.

Step 13: Reinstall the undertray

• Reposition the splash shield and start all screws by hand.
• Use Torx T25 screwdriver and Torx T30 screwdriver to tighten the fasteners snugly.
• Replace any broken clips using the trim clip removal tool.

Step 14: Lower the car

• Use the floor jack (3-ton) to lift slightly, remove jack stands (3-ton), then lower the car fully.
• Remove the wheel chocks.

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✅ After Repair

• 🔍 Start the engine and let it idle; expect smoother idle and less vibration if mounts were collapsed.
• 🧪 With the hood open, lightly blip the throttle in Park; watch for excessive engine rocking (there should be less than before).
• 🚗 Test drive and listen for clunks on takeoff and on/off throttle transitions.
• 🔧 Recheck for any undertray rubbing noises and verify all fasteners are tight.

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💰 DIY vs Shop Cost

Shop Cost: $900-$1,600 (parts + labor)

DIY Cost: $180-$450 (parts only)

You Save: $720-$1,150 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 3-5 hours.

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🎯 Ready to get started?

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