Your engine weighs a couple of hundred kilos and produces constant vibration. Engine mounts hold it in place and stop that vibration reaching the cabin. When they wear out, the car does not stop working, so owners often live with the symptoms for months. That is a mistake, because a sagging engine puts extra strain on hoses, wiring, exhaust joints and the gearbox mounts.
This guide covers the signs of a failing mount, how to confirm it, the difference between rubber and hydraulic mounts, and what to check before you order a replacement for your Mercedes or BMW.
What an engine mount actually does
A mount is a metal bracket with a rubber or fluid-filled element in the middle. It connects the engine to the subframe or body. Most cars have two or three engine mounts, plus a separate gearbox mount. The rubber slowly hardens, cracks or tears with age, heat and oil contamination, and the engine is then free to move more than it should.
Symptoms of a worn engine mount
- Vibration at idle. The steering wheel, seat or gear lever buzzes when stopped in gear, and often settles down when you put the car in neutral or park.
- Clunk or thump when you pull away, change from drive to reverse, or lift off the accelerator sharply.
- Shudder on start-up or shut-down. The engine rocks noticeably when switched on or off.
- Engine bay noises over bumps, as the engine moves and touches other components.
- Visible damage: cracked or split rubber, or oily wet patches on a hydraulic mount where fluid has leaked out.
Similar symptoms can also come from a worn gearbox mount, a misfiring cylinder or a loose exhaust hanger, so do not assume the mount is the only cause.
How to confirm it
- With the car safely parked and the handbrake on, have a helper watch the engine from the front while you shift between drive and reverse with your foot firmly on the brake. A mount in good condition lets the engine move only a little. A failed one lets it lurch or lift visibly.
- Inspect the mounts with a torch from above and below. Look for cracks, rubber separating from the metal, and fluid leakage.
- Have a workshop check for fault codes and misfires, so you rule out an engine problem that is mimicking a mount fault.
Do not put any part of your body under a car supported only by a jack. Mount inspection and replacement means supporting the engine and removing load-bearing brackets, so have a qualified workshop do it.
Hydraulic vs rubber mounts
Rubber mounts
These are a simple solid rubber block bonded between two metal plates. They are robust and the failure mode is usually obvious: cracking or tearing.
Hydraulic mounts
These contain fluid inside chambers that damp vibration across a wider range, giving a smoother idle. Many Mercedes-Benz and BMW models use them. When the internal membrane fails, the fluid leaks out and the mount goes soft or noisy. Some designs also include a vacuum or electrical connection that switches the damping, so the plug or sensor on the replacement must match your car.
Mounts with sensors or electronics
Certain Mercedes models use switchable or sensor-equipped mounts. Always compare the connector and the number of pins on the old part with the new one. A mount that looks identical but lacks the correct connector will not work properly.
The golden rule is to replace like with like. Swapping a hydraulic mount for a plain rubber one, or the other way round, can change how the car feels and can cause new vibrations.
Replace one or all?
Mounts age together. If one has failed, the others have done the same mileage. Ask your workshop to inspect all of them while the engine is supported, since the labour is the largest part of the job. Replace the ones that are damaged or leaking.
What to check before you buy
- Match by make, model, year and chassis code (for example W205, W212, F10, G20).
- Confirm the engine type: petrol and diesel versions of the same model often use different mounts.
- Note the position: left, right, front or rear. They are not interchangeable.
- Check the OEM number on your old mount, or have the workshop read it from the parts catalogue using your VIN.
- Compare the mount type and connector (rubber, hydraulic, sensor) with the old part.
Not sure which one you need? Send photos of the old mount and your VIN on WhatsApp at +91 9958122339 and we will help you match it.
Frequently asked questions
Can I keep driving with a bad engine mount?
For a short time, yes, but it is not wise to leave it. The extra movement strains other components and can lead to bigger repair bills. If the engine moves heavily or you hear loud knocking, get it checked soon.
Why does the vibration go away in neutral?
In gear, the engine is pulling against the drivetrain and the load on the mounts rises. A worn mount cannot absorb that extra movement, so the vibration appears. In neutral the load is lower.
Do I need to replace the gearbox mount too?
Not necessarily, but it is worth inspecting at the same time. Both mounts do similar work and show similar symptoms when they wear.
Find the right mount for your car
German Purje stocks engine mounts for a range of European models. Browse parts for your make: Mercedes-Benz replacement parts or BMW replacement parts. For C-Class owners, see our Mercedes C-Class W205 collection. Always confirm fitment by chassis code and OEM number before ordering, and have the mount fitted by a qualified technician.