Rotten eggs smell with bottom engine rattling noises

[Matyoka]

Thanks, the rattling comes from the opposite side as far as I can tell and I am under the vehicle. I wonder if the power steering oil reservoir rattles to the touch in your wife's E70? I will shoot a video of mine, I will place a glass of water on it

[andrewwynn]

We no longer have the 50i. That said use a vibration app with your phone to find the source. Also mechanics stethoscope would be helpful.

Dan 63 does not use the belt tensioner so I suspect you have something out of round on one of the attachments to the serpentine.

The best way to rule out is to remove the belt/s.

The AC belt is stretched on Soo that's a bit of a chore the main belt is not hard to do just find a YouTube video to show how. Also of course don't run the engine long with no coolant pump

[Matyoka]

Today I opened up the small coolant reservoir under the BMW emblem to realize it was totally empty... unreal. Who knows how long I've been driving this thing empty. Also just learned today from a Youtube vid that there are 2 tanks working individually from each other. SMH...

[Matyoka]

Originally Posted by andrewwynn

We no longer have the 50i. That said use a vibration app with your phone to find the source. Also mechanics stethoscope would be helpful.

Dan 63 does not use the belt tensioner so I suspect you have something out of round on one of the attachments to the serpentine.

The best way to rule out is to remove the belt/s.

The AC belt is stretched on Soo that's a bit of a chore the main belt is not hard to do just find a YouTube video to show how. Also of course don't run the engine long with no coolant pump

Thanks Andrew, unfortunately my mechanical skills stops at the oil change. This will be a job for a BMW mechanic hopefully next week. Appreciate your help.

[andrewwynn]

Post the results so other people can learn


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[Matyoka]

Originally Posted by andrewwynn

Post the results so other people can learn

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Absolutely!!! Filled up the center cooler tank, drove around the hood but no changes... still rattles on and off.

[andrewwynn]

Wife's first X5 had major rattles. Turned out to be stones on the stiffening plate


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[bcredliner]

Is there an intermittent rattle if the engine is just idling? If it is only under acceleration the issue may be engine timing related or low octane gas.

[andrewwynn]

The shaking reservoir suggests something on the serpentine belt is causing a shake or possibly engine mount.

I use this app:

https://apps.apple.com/app/id1089589547

To find vibrating things. You can find the frequency and compare to rotational speed of each accessory on the serpentine belt with a little math. Take video at 240 fps and count frames.

Also the best way to find sound source is an FFT app.

This is the one I use:

https://apps.apple.com/app/id298840058

I've found a few bad wheel bearings using this app.

[ard]

Just to clarify...no check engine lights, no codes??