Problems with the crankshaft pulley and engine mounts: symptoms, cost and affected models
We have documented 5 faults with the crankshaft pulley and engine mounts in 5 engines, affecting 48 models of car in our database. The most important by severity and frequency: crankshaft pulley (vibration damper) failure (M112 / M113), crankshaft pulley vibration damper wear (BMW N57) and crankshaft pulley vibration damper failure (BMW M57).
How it works and why it fails
Crankshaft pulley and engine mounts
The crankshaft damper pulley filters engine vibrations before they reach the auxiliary belt, and the engine mounts (rubber bushes) hold the engine to the body. Both contain rubber that degrades with age and heat.
What to do
Vibrations at idle, thumps when accelerating or lifting off, noises from the auxiliary belt or a pulley that wobbles are warnings. If the rubber on the pulley separates, the belt can come off and leave you without an alternator or power steering.
General explanation by MotorFiable. The specific faults of each engine and car, with their sources, are on the linked pages.
Common symptoms
The symptoms that come up most often in the documented faults with the crankshaft pulley and engine mounts. Open each one to see what other faults cause it.
Problems with the crankshaft pulley and engine mounts by engine
From most to least important (severity × frequency). Each page details the affected versions and years, symptoms, cost and how to check for it.
- 1High severityOccasionalFrequency: OccasionalM112 / M113Crankshaft pulley (vibration damper) failureYes: on some units of the M112 V6 and the M113 V8 the crankshaft pulley can come loose or fail and, in the worst case, cause serious engine damage. German guides cite a wobble or a rattle in the engine bay as a warning.
- 2Medium severityCommonFrequency: CommonBMW N57Crankshaft pulley vibration damper wearThe N57's crankshaft vibration damper (pulley) wears with use and, according to a technical guide to the engine, usually needs replacing between 80,000 and 120,000 km, giving warning with abnormal noises before failing completely.Appears at around 80,000 km
- 3Medium severityOccasionalFrequency: OccasionalBMW M57Crankshaft pulley vibration damper failureThe M57 crankshaft vibration damper (pulley) can fail with use, warning with abnormal noises and knocking at the front of the engine before it breaks completely.
- 4Medium severityRareFrequency: Rare1.4 HDiCrankshaft damper pulley wearThe crankshaft pulley incorporates a rubber ring that dampens engine vibrations and that can lose grip or crack over time. We have found only one specific report of this fault (a Peugeot 206 at around 250,000 km), so we do not consider it a widespread fault.
- 5Low severityOccasionalFrequency: Occasional1.2 12VVibration from worn engine mountsThe 1.2 12V is a three-cylinder engine with a background vibration inherent to this design; on top of that, in some documented cases, premature wear of the engine mounts increases the vibration felt in the cabin.
Engines with faults with the crankshaft pulley and engine mounts
Problems with the crankshaft pulley and engine mounts in your car
2 cars have several documented faults with the crankshaft pulley and engine mounts. Choose yours to see only the ones that affect them, by engine and by year.
Frequently asked questions
Which engines have the most faults with the crankshaft pulley and engine mounts?
By severity and frequency, the M112 / M113 (crankshaft pulley (vibration damper) failure, high severity), the BMW N57 (crankshaft pulley vibration damper wear, medium severity), the BMW M57 (crankshaft pulley vibration damper failure, medium severity), the 1.4 HDi (crankshaft damper pulley wear, medium severity) and the 1.2 12V (vibration from worn engine mounts, low severity).
What symptoms does a fault with the crankshaft pulley and engine mounts cause?
The most frequently cited in the documented faults: abnormal vibrations or unstable idle, deep metallic engine knock and metallic timing noise on start-up.