M113 Noise

[yinujim]

Hi guys I have a M113 engine here that has a weird whirring/whine noise. At first I thought it might be the crank pully but now I'm thinking it could be oil pump related. Is this a common issue with M113's?

Thanks

 

[LostKiwi]

Most common cause of noises is the belt tensioner or belt idler pulleys.
Remove the serpentine belt and briefly run the engine to verify.
Turning the pulleys by hand will also show any bad bearing.

Also check for delamination of the crank pulley harmonic balancer.

 

[yinujim]

The video is with the belt off the engine.

 

[brandwooddixon]

I would say possibly gearbox idle shaft bearing.
If the gearbox has been switched back and forth between drive and neutral a lot e.g., whenever stationary, this can cause excessive wear.
This is exacerbated if the gearbox oil hasn't been changed regularly - a common issue on cars of a certain age as MB sold them as having gearboxes sealed for life.
Check this by running the engine then moving between neutral and drive. The noise will be more noticeable in neutral.

 

[yinujim]

Thanks. The noise seems to stay the same regardless of gearbox position. I think I do have history of the mechatronics being rebuilt 10K miles ago so I would assume they did a filter change too. It only has 92K miles.

 

[Uncle Benz]

Oil pump chain can stretch and rub on a part of the timing chain case. Very common. Not really a cause for concern but if you have it apart for anything big worth addressing while you are there

 

[yinujim]

Yes that kind of makes sense now along with the O rings that can go bad from the pickup to the pump. I would rather not have to drop the subframe and the lower and upper pan.