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-)

[Bronco Biff]

I'd lean nore toward the tranny than than the main. Never heard a main squeal.

[broncosbybart]

Can't help much on this one. Rod bearings usually go before the mains do. (Picture a sewing machine type knock). Let us know what you find.

[firefighter2134]

Main bearings will make a chiping sound. Check to see if you have any play in the crank. You can use a prybar behind harmonic balancer. If it doesnt move out try pushing on it and see if it will slide to rear. If thrust washers on either side of main bearings are bad it will allow play in crank. Also will make chirping soud seem like it coming from tranny

[chuzie]

I am out of the country. It sounds like chirping so I will do as you suggest when I return. Thanks.

[DirtyWhiteBoy]

Most Main bearing will have a low vibration tone almost a humm. that sounds like tranny problems.

[chuzie]

WOW! Just friggin WOW!

Pulled the transmission today with the intention of replacing the pump. When i got it off I saw evidence the flexplate had been rubbing against the shroud as seen below...







The white you see on the outer diameter of the flexplate is white chalk I was using to troubleshoot when it was still installed but it had been rubbing there at some point as indicated by the galling on the shroud as well as in multiple other places as denoted by the permanent marker.

As soon as I saw this I thought I had the answer and did not pull the pump to investigate further. Though I know the sound of the plate rubbing on the shroud is much different, like a lighter metal scrapping sound unlike what I currently have, I figured it may sound different especially at the inner diameter of the shroud where it is more secure.

I cleaned up the galling from the shroud and cut about 3" from the inner diameter to ensure it never rubs again. Purchased a new flexplate just in case it was warped and even threw in a new converter just in case swelling was an issue. Dropped a cool $300 on those two items.

Installed everything and cranked it up only to hear the same sound!!!!! OMG!!!

Anyway, I am at a complete loss now. I am so sure the sound is coming from this area but I am 100% positive it is not the shroud or the starter.

Here is a recording of the sound. Maybe someone can listen and help me figure out what it is...PLEASE!

http://youtu.be/DrzACYKy6wY

Is seems to be more prominent in NEUTRAL and SOMETIMES goes away in DRIVE or REVERSE but not always.

Here is a crappy shot of pump...



Thanks. :-[


Sent from my Droid using Tapatalk 2

[broncosbybart]

read about this on classic as well. this really sucks. i can't offer advice, but hope you find it soon!

[broncomatt]

We had talked about this being a possible, The pump and torqe converter should be replaced next. Now that the main bearings have been ruled out thats where I would go next. The other thing to look at is your starter. Make sure its not slipping back engaged. Most likely the pump is pushing the torqe converter back until the flex plate rubs on the spacer plate.

[DirtyWhiteBoy]

That doesnt sound good but I've never heard a main bearing like that. this might sound stupid but check the starter location for any signs rubbing. TIM