1983 245, 376,000 miles and change. Original B23F and M46.

I had a new clutch put in about 3 years and 15,000 miles ago. The mechanic who did the work is a well respected Volvo specialist who has worked on my car for over 20 years, and he used OE parts (Sachs). The pilot and throw-out bearings were replaced, the flywheel was resurfaced, he replaced the rear main seal and the transmission mount.

About a month ago, the car started making a horrible noise. It sounds like a bearing going south. The pitch increases/decreases with the speed of the transmission. For example, if I accelerated up to 45 mph in 4th gear, then push in the clutch and downshift into 3rd, the whine increases dramatically in pitch and volume, even though the car is coasting (engine rpm at idle). Shift back into 4th, without letting the clutch out, and it quiets down considerably.

There is also a "rushing" sound (like running water) when the car is stationary and the clutch is engaged. If I push the clutch to the floor, the sound stops.

How do I tell the difference between a bad T/O bearing and internal transmission problems?

I have the same problem,is it hard to change the main input shaft bearing? Is there any special tools needed?

Could also be the cluster gear in the bottom of the tranny. It is always turning when the input shafts is turning. You're going to have to remove the tranny and disassemble it to find the problem. Tom

It sounds like a transmission bearing to me.

To determine if it's the front half or rear half of the trans... get going down the road like 50 MPH and throw the trans into neutral and kill the engine. (Don't lock the steering wheel!)

Does the noise continue? Indicates a problem on the trans output side.

Does the noise stop? Indicates a problem on the trans input side.

Also, if the car is stationary, in neutral, clutch engaged, and it's noisy, that indicates the input side. What if it's parked in neutral, clutch engaged, and you rev the engine up and down? Does the noise increase/decrease with engine speed?
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

Hi,

From what you are describing to me it sounds like it’s a main input shaft bearing.
When you have the clutch engaged and the transmission in neutral, it is spinning only that shaft.

When you are using only the fourth gear you are running the output shaft at the same speed as the input or closer to a one to one ratio.
This overall selection is Slower than when you are in lower gears building up a torque advantage. When you shift down there is a counter shaft that is picking up speed as the gear diameters change in size and therefore speed.
Pressure shifts through the teeth engagements and the thrust of pushing the car is transmitted through the lengths of the shaft. The bearings are having to hold them in place.

When you are in neutral, the wear around of the rolling elements of the bearings are moving around.
When this happens the gears teeth are also moving back and forth and in and out of engagement. This is due to some radial play of the bearing as the two shafts are not held in parallel.

In many cases it’s the first or most outer bearing. It’s the largest, spins at engine speed almost all the time and is usually the loudest because it closest to, guess what, a bell housing! Might as well be a audio speaker cone.

Basically, You have a lot of miles on this transmission!
A little excess play is everywhere. It doesn’t get better with things shifting or sliding sideways.
Put in New bearings and getting the lateral play corrected with shims and it should stop it.

How does it shift from one gear to another ... smoothly?
Is the oil in there fairly free of metal ... brass or steel sparkles ... during recent oil changes?
You might have to consider the synchro’s or another transmission with less miles.
If this one is good, then keeping what you know! A new bearing, here or there, might be better than trusting some ship-shod transmission shister.

It seems that your mechanic did you a good job! He did all the right things back 3 years ago.
Questions are, was he reasonable?
Does he know someone?

Phil