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

chuzie · Dec 7, 2012

'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. No abnormal conditions lately nor any extreme RPM encounters.

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

Thanks as always.
Mike

ratio411 · Dec 7, 2012

Doesn't sound right.
I had a main bearing go out, and the symptom was oil pressure that went down, instead of up, with rpms.
Then as the rpms came down, the oil pressure shot up very high, and then dropped down to about 10 psi when the rpms settled down to idle.
It was really odd. Didn't make any noise, but it never spun a bearing either.

To me it sounds like you have an issue with the flexplate, starter, torque converter, or transmission front pump.
A failing front pump on the tranny sounds exactly like what you are describing, in my mind anyway.

chuzie · Dec 7, 2012

Well crap! I did just installed a 4R70W from the junkyard that was super clean with less than 100K on it. Not sure what I would prefer now, a bad trans pump or a bad rear main bearing.

Lesser of two evils...

If it is the trans pump, I am guessing I won't know when it bites the dust until my trans stops functioning.

Really need to find a way to isolate the issue better so I can determine what part is faulty here.

Oh happy day.

gearheadboy · Dec 7, 2012

Loose converter nut, broken flex plate, or broken crankshaft. Not a bearing.

chuzie · Dec 7, 2012

Gotcha. Ya, i was also told if it was an engine bearing, it would have likely siezed by now as i have put about 40 miles on it since this started so likely eliminate that as a possibility. More to come...

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chuzie · Dec 14, 2012

Pulled oil pan and saw no obvious issues and rear bearing looks fine.

Pulled the transmission 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!

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. :-[

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65ShelbyClone · Dec 14, 2012

It squeals until the engine stops, so can you get it to do that when turning the engine over manually?

FYI, the bearing responsible for controlling axial crankshaft movement is the #3/middle/thrust bearing.

gearheadboy · Dec 14, 2012

Start it without the tranny in?

chuzie · Dec 15, 2012

I have rotated it manually and cant duplicate it, however; my cranking is a bit slow.

Considered starting with no trans installed but have been told it is risky as we cant predict movement of engine. Risk killing radiator, etc.

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gearheadboy · Dec 16, 2012

Put a jack under the pan. No issues.

gearheadboy · Dec 16, 2012

Whatever it is is still spinning for a second after engine stops. It is for sure in the trans or converter. You stated you replaced the converter.

chuzie · Dec 16, 2012

Gonna drop oil pan and take another look @ thrust bearing before i start digging into trans again. Thanks

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smarek · Dec 17, 2012

I had a very similar sound in mine (with a manual trans) particularly the way yours tails off at the end. It was the fuel pressure regulator. Since that is at the rear of the engine it could easily make you think tranny or bearing. If you have a mechanics stethascope listen to the fuel rail/regulator. Pull the vacuum line to the regulator to see if the sound changes. It may not but if it does you probably have found the problem.

chuzie · Dec 17, 2012

No observed pressure fluctuations on gauge when sound occurs but i will pull the vac line anyway just in case. Thanks

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smarek · Dec 17, 2012

I've got a fuel press gauge on the A pillar, it was rock steady when the noise occured. The sound would change some with load/rpm but the frequency of the noise didn't stay sync'd. to rpm. The other thing to try is turn on the key, no start, to run the fuel pump for a few seconds. Do that before starting the engine or right after you shut it off. Best if you can do it while the noise is dying out (the noise tailing off is the fuel pressure bleeding off).

I think it was the regulator, it "fixed" itself before I had a chance to replace the regulator which is super hard to get to on mine.

chuzie · Dec 17, 2012

Okay so I had just enough time today to run out and check the endplay. I measured from the face of the flex plate. Tapped the balancer all the way aft, zeroed out the dial indicator, then pried the balancer forward. I ended up with .0125. I believe that is just out of limits but wonder if that is truly enough to be eating through the bearing and making such noise? I cranked it up and there was no sound until it warmed up and I punched the throttle; then it started the noise. I tried to see if moving the crank full forward or aft would change the sound. Each time, it took approximately 4 seconds after engine start for the sound to begin. I crawled under the oil pan with a stethoscope and spent a decent amount of time trying to locate the sound and I am confident it is most prevalent near the middle of the oil pan. That is the only area I can pick up the squeaking on the stethoscope although my ears tell me it seems to be originating from the flex plate area. I get no squeaking when I place the scope on the oil pan bolts near the rear main.

Grounded the FP circuit and disconnected the vac line. Positive it is not coming from the press reg.

With the endplay out of limits and the apparent location of the sound, I am inclined to go with thrust bearing. I will pull the pan when I get back in town next month and replace it so stay tuned.

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chuzie · Dec 18, 2012

Need purchasing guidance for bearings.

Crankshaft undersize?
Groove location?
Groove style?
Bearing material?

Any suggestions?

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gearheadboy · Dec 18, 2012

Ok here is something I've not tried on a Ford. If you unbolt the torque converter can you slide it back into the pump far enough to start the car without the converter spinning? If so you can eliminate the trans and converter. It sounds to me like the noise continues for a second after the engine has stopped totally. Which means the torque converter external portion is stopped but the internal would still spin for a second driving the transmission pump. Lay under and watch the crank pulley with a light to see if it is stopped before the noise stops while someone else shuts it off.

chuzie · Dec 19, 2012

I dont think it is possible to slide it far enough back but i can take a look. I can also lock the converter manually with a switch. Maybe jack the rear tires off the ground, lock the converter and throw it in first. Maybe enough to kill engine?

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88LX5.Oh · Dec 19, 2012

gearheadboy said:
Ok here is something I've not tried on a Ford. If you unbolt the torque converter can you slide it back into the pump far enough to start the car without the converter spinning?

Negative. Because if you just throw a Ford trans up and bolt it to the block without lining up the converter with the flex plate, it'll literally smash the converter back into the pump and you run the risk of ruining the pump. Ask me how I know
Now if we were working on a GM or a Dodge, this would totally work and would be an excellent idea

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

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