Engine mounts: symptoms and checking

In short: Worn engine mounts show up as knocks when starting and stopping and as idle vibration that fades with rising revs.

Symptoms

Typical signs are:

• knocking or shaking when starting and switching off
• idle vibration that eases noticeably towards 1,500 rpm – provided the balance shafts are set correctly
• visibly cracked or peeling rubber
• with severe wear, a ruptured mount leaking fluid

Checking

Installed mounts can be checked with a wire bent into a bracket shape with its points 60 mm apart: if it no longer fits between the load-bearing surfaces, replace the mount. A new mount measures 70 ± 1 mm.

Easily confused

Idle vibration can also come from an incorrectly fitted balance shaft belt, so mounts and belt drive belong together when diagnosing.