Troubleshooting help

[Alpina540i]

Good morning,

So I started hearing a growling/roaring/vibration in the engine area a few days ago.

It exhibits this while sitting at idle as well. It seems to be engine load/rpm dependent, the growl/vibration comes and goes while crossing different rpms.

It feels like something is almost loose and there is a definite vibration felt through the car that is coupled with the growling sound.

I have replaced the water pump alternator but power steering and AC compressor are original.

I took the belt off the AC WP PS and the sound vibration seemed to still exist at low rpms 500ish, didn't drive it as no alt or cooling present.

Car has fresh timing chain components.

Any ideas on what could make a grinding growl sound? Its got me stumped, as much noise as its making it should be obvious.

Thanks

-Anson

[Pelican Parts]

Hello Anson - are you able to post/link a video to this sound? It may be easier for members to give advice if there is a sound clip of the noise. Has the car been performing normally prior to this sound? Do you feel the vibration under the driver's side floor?

[Alpina540i]

Well upon further investigation I think it's an exhaust leak from the passenger side bank close to the engine.

Yes the car runs like a scolded cat.... Very well smooth.

Haven't been able to get it on a lift yet to look or record. The resonance at certain rpms is definitely exhaust leak sound.

Are there any common exhaust leak spots near the cats?

Thanks

[motion]

"Fresh timing chain components" how fresh? What components? Did you replace the tensioner? What about the fat "O" ring (11141736753) between the upper timing chain cover and head? When you get it up check the exhaust manifold to cat joints.

[JimLev]

That p/n doesn't exist, you probably mean 11141736758.
That o-ring shouldn't cause any noise or vibration.
Check the nuts on the back side of the CAT that holds the pipe to the CAT, they have been to disintegrate resulting in a loose connection.
Also check the secondary air valve and gasket, the outlet of the valve has exhaust pressure at it.

[Alpina540i]

"Fresh timing chain components" how fresh? What components? Did you replace the tensioner? What about the fat "O" ring (11141736753) between the upper timing chain cover and head? When you get it up check the exhaust manifold to cat joints.

Timing guides, tensioner, chain everything done 25,000 miles ago.
Yes o rings replaced as well as besian vanos seals and oil check valves.... Etc.

[Alpina540i]

That p/n doesn't exist, you probably mean 11141736758.
That o-ring shouldn't cause any noise or vibration.
Check the nuts on the back side of the CAT that holds the pipe to the CAT, they have been to disintegrate resulting in a loose connection.
Also check the secondary air valve and gasket, the outlet of the valve has exhaust pressure at it.

Noise and resonant Vibration I have.

So the pipes from the X over to the 2nd set of cats has been known to leak? First cats are a part of the headers.

Thanks Jim!

-Anson

[edjack]

Remove the cross strap aft of the cats. Report back.