Skip the auto shop - Our mechanics make house calls

Q: Crank shaft wobbly

asked by on

Hi my Subaru recently made a noise I checked under the hood and realized that the pulley was wobbly the next day my battery was drained and car would t start I took the battery out and charged it again and it worked but will stall randomly as soon as I come to a stop or idle goes anywhere below 1000 rpms could this be caused by a loose cranckshaft and what should I do in this situation ?

My car has 345000 miles.
My car has a manual transmission.

A: Hi there. On the "front" end of t...

Hi there. On the "front" end of the crankshaft is a harmonic balancer held on by one large bolt that is torqued to 132.8 ft. lbs that is pretty tight. It’s not too likely that the bolt is "loose". The "balancer" though has two integral pulleys bonded to it that accommodate serpentine belts. If the rubber bond between the pulleys and the rest of the balancer has broken, the pulleys may appear wobbly or loose. The balancer performs a very essential function in dampening torsional forces applied to the crankshaft so if you suspect an issue with the balancer, it is best to get it repaired quickly because a faulty balancer can cause damage to the crankshaft.

Be careful who you select for the work. Using an air gun to remove that tight nut is fine but it is completely improper to use an air gun AT ALL to tighten the nut because such will damage the crankshaft, bolt and balancer. Consequently, there is a very specific procedure to install the new balancer which involves using a torque wrench to torque the bolt initially to 32.5 ft-lbs. Then after torquing the nut to a finished value of 132.8 ft-lbs., the mechanic needs to confirm that at least 65 degrees of arc was passed through in reaching that value of 132.8 ft-lbs. If not, the bolt is no good and a new bolt should be used. To avoid going through this kind of measurement, it is possible to just simply use a new bolt which might be cost be fairly cheap as a dealer item (the bolt is OEM only).

At any rate, if you want it done right, make sure the mechanic has a proper high capacity torque wrench. If you would like to have this taken care of, a certified professional from YourMechanic can come to your car’s location to inspect the noise and stalling issue to make the proper adjustments or repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Noise when shifting at lower speeds - 2008 Jaguar XK

There are 2 possible sources of the "vibration noise" under the circumstances you outline. First, have the driveshaft and center support carrier checked for balance, proper alignment and lubricaion. Second. have the transmission's torque convertor evaluated. Both items have some...

Q: Rattling Sound - 2007 Subaru Impreza

Hey there. I suspect you have an engine-mounted bracket that is touching a heat-shield or other metal component under the hood, generating the noise you hear. Get a helper to hold the brake, and put the car in gear while...

Q: 2001 Dodge Interprid, starts and then dies

Your symptoms sound very similar to a vehicle experiencing a faulty idle air control valve. Air metering is very important in the operation of the engine and a faulty valve, sensor, or air leak can throw things out of whack...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...