5.0 rear main bearing... is it going out???

[chuzie]

'87 5.0HO EFI mileage unknown

Noticed a high pitch chirping sound today and thought it was just the serp belt acting up. Upon further investigation, I narrowed the area to the rear of the oil pan. I initially thought it could be the flexplate rubbing the shroud but I am pretty sure it is in the engine oil pan.

The sound it high pitch chirping and frequency changes with RPM. I feel a vibration on the pan with a frequency coincident with the sound.

I have never dealt with engine bearing issues but I can't think of anything else this sound could be.

I have been running this engine for about 10 years, put about 3,000 miles on it per year and have had temp issues in the past which have been resolved. My oil pressure has always seemed low like 25psi but the pressure has not changed with the discovery of this sound and my oil level and condition are fine.

Does anyone have any thoughts about what else it could be or how I can further confirm my possible diagnosis?

EDIT: The consensus from most folks is possibly the auto transmission pump or the torque converter in my 4R70W and NOT the rear main bearing considering how unlikely it is for the engine to still be running with such bearing noise.

The 4R70W has about 1,000 miles on it since installation and it came from the salvage yard with about 100,000 miles or so.


Thanks as always.
Mike 8-)