Ugly bearing noises

projectnitemare · Feb 4, 2008

In my 89 BII w/ a 2.9/FM146/1350, the trans is making a very nasty bearing noise in 1st, 2nd, 3rd, 5th and reverse. It does it when the clutch is out in any of those gears as well as neutral also when the clutch is depressed in those gears (except neutral). I'm assuming input shaft bearing but not too sure since I haven't ripped into it yet. I'm not too worried since I have a replacement trans but rather if I should even tear it apart to fix it for a spare. Any ideas?

Matt

brendank · Feb 4, 2008

projectnitemare said:
In my 89 BII w/ a 2.9/FM146/1350, the trans is making a very nasty bearing noise in 1st, 2nd, 3rd, 5th and reverse. It does it when the clutch is out in any of those gears as well as neutral also when the clutch is depressed in those gears (except neutral). I'm assuming input shaft bearing but not too sure since I haven't ripped into it yet. I'm not too worried since I have a replacement trans but rather if I should even tear it apart to fix it for a spare. Any ideas?

Matt

I don't know much about the FM series transmissions, but if you have noise in all gears and not 4th, which is 1:1, I would suspect a countershaft bearing or the bearing that is in between the mainshaft halves.

Jspafford · Feb 5, 2008

You nailed it. It's the input shaft bearing. Especially since it's noisy with the clutch out in neutral.

brendank · Feb 5, 2008

Jspafford said:
You nailed it. It's the input shaft bearing. Especially since it's noisy with the clutch out in neutral.

If it was the input shaft bearing, don't you think it would do it in 4th as well?

MAKG · Feb 5, 2008

brendank69 said:
If it was the input shaft bearing, don't you think it would do it in 4th as well?

Maybe, or maybe not. But the noise would be dramatically reduced in 4th if it was there at all.

4th gear is axially symmetric; there are no transverse or axial forces; only torsional. Every other gear pushes the input and mainshaft apart, and the countershaft away from the other two shafts.

As for neutral noises, the synchronizer assembly can provide some support in 4th, but not in neutral.

And by the time neutral is noisy, the transmission is usually D E A D.

Evan · Feb 5, 2008

MAKG said:
4th gear is axially symmetric; there are no transverse or axial forces; only torsional. Every other gear pushes the input and mainshaft apart, and the countershaft away from the other two shafts.

Good point and well put. I never thought about that.

projectnitemare · Feb 5, 2008

I was thinking along the lines of MAKG. I knew when I changed the engine and saw the pilot shaft bearing missing there would be trouble. I only have $800 in the thing, including tags, inspection, parts and so on. It's really eating into my spare parts bin but that's why I had them in the first place. I'll probably do a tear down evaluation on it and just throw it away.

Matt

reno · Feb 5, 2008

What about a trans that makes a hissing sound (almost like a small vacuum leak) in 1,2,3,and 5, but quiet in 4 and neutral? Sometimes it is hard to put into 1st, and sometimes it is hard to shift from 1st to 2nd. What could cause this?

MAKG · Feb 6, 2008

That's an earlier form of the same class of faults. It may or may not be cost effective to rebuild; only a teardown will tell for sure. Unfortunately, for an M5OD, a likely cause is a hosed bearing between the input and mainshaft (which doesn't rotate at all in 4th). This is usually caused by oil starvation, in which case, the fault is only the most obvious of many. If it is a loose or worn input bearing, now is the time to replace it.

reno · Feb 6, 2008

Is this an easy fix that an average person can do? Or is a shop in my future? What is an average cost for this or an overhaul? Or at least how much should a junkyard tranny cost (Average)?

mhughes165 · Feb 6, 2008

MAKG said:
Maybe, or maybe not. But the noise would be dramatically reduced in 4th if it was there at all.

4th gear is axially symmetric; there are no transverse or axial forces; only torsional. Every other gear pushes the input and mainshaft apart, and the countershaft away from the other two shafts.

As for neutral noises, the synchronizer assembly can provide some support in 4th, but not in neutral.

And by the time neutral is noisy, the transmission is usually D E A D.

not nescesarrily tru, when i got my old 87 ext cab it was making the dreaded bearing grind that he was experiencing, the truck had 197k miles at the time, and was a oncall vehicle for the towns fire chief for many years, original trans, i drove that truck that way and wheeled the piss out of it up to 327k miles, until the original motor went, dropped in another 2.9 that i hydrolocked in short order, at that point the trans went into my buddys ranger, and since then he has put over 50k miles on the transmission, could it be a fluke occurence......

Jspafford · Feb 6, 2008

Your right....It could be.

But it is most likely not going to get any better. When mine started doing this it was not long until it was so loud I couldn't stand it. It makes more noise in the winter when the gear oil is cold.

In 4th gear the mainshaft is connected to the tailshaft so everything else is along for the ride with no stress on it. Hence the reason it's not as loud in 4th.

Just keep driving it, but have a spare ready.

mhughes165 · Feb 6, 2008

Jspafford said:
Your right....It could be.

But it is most likely not going to get any better. When mine started doing this it was not long until it was so loud I couldn't stand it. It makes more noise in the winter when the gear oil is cold.

In 4th gear the mainshaft is connected to the tailshaft so everything else is along for the ride with no stress on it. Hence the reason it's not as loud in 4th.

Just keep driving it, but have a spare ready.

ya, i dont see the point of replacing something until it stops doing its job, sure its annoying, but after awhile it becomes ur companion and keeps you company on long drives :yahoo:

Jspafford · Feb 6, 2008

Just keep telling yourself that when your sitting on the side of the highway 500 miles from home.

MAKG · Feb 7, 2008

mhughes165 said:
ya, i dont see the point of replacing something until it stops doing its job, sure its annoying, but after awhile it becomes ur companion and keeps you company on long drives

Can you predict when it will happen?

'Cause more likely than not, it will strand you in a very inconvenient place. Like in the middle of the freeway at rush hour. Or while you're towing something heavy up a mountain 1000 miles from home and 100 miles from the nearest town.

Ugly bearing noises

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Logan Andrew Feb 17, 2012

It's only money...

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Logan Andrew Feb 17, 2012

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