I have a relatively new to me Excursion. It seems to run well and shift well but recently I've become very aware of a strange hum, thrum, and vibration in the floor boards. The sound and vibration have a definite cadence/pulse.


Here is what I have observed trying to source the sound.

Occurs around 2500 rpm and continues up to 4000 haven't really gone past 4k to know about after that.

Occurs in Park, neutral and drive and is more noticeable under load especially when towing. It is not really noticeable under my normal driving style it gets lost in the running gear until the X is at around 3600 RPM's which typically doesn't happen unless I'm pulling a long grade with a trailer. It was only after testing at a standstill in park and neutral that I realized it actually starts at approximately 2500.

Other than the vibration and low frequency hum starting at 2500 there are no real indicators of reduced performance or other problems but it's got me nervous.

I'll post more as I try to isolate the sound.

Appreciate any ideas or experience with this. I'm going look over the exhaust but it doesn't feel like a leak to me or the usual manifold bolts shearing. I'm having a hard time describing it, it's not a creak, click, rattle or tap. It's a hum/roar. I've been reading up on the entire rig and have learned much but nothing I've read is quite what I'm experiencing.

 

Try posting an audio of the sound.

 

Since it makes the noise in neutral as well as when driving, remove the lower torque convertor sheetmetal cover and using a flashlight look up between the TC and engine. Look for cracks in the flexplate (flywheel), there have been a few cases of this happening, any sign of cracking there requires immediate replacement of the flexplate.

 

No cracks or other defects observed. I did see that the rear most passenger side cylinder/exhaust manifold has been leaking...

Still need to post the sound, I need to break out a condenser microphone the phone didn't capture it.

Thank you for the suggestion I really do appreciate it.