348 TB whining sound

I have a 90 348tb with 40k on it and it makes a whining sound I cant quite figue out. Im a master technician and have built and tuned a lot of high horse power cars from 125hp-1000+hp so Im pretty competent to say the least.
The sound is somthing like an automatic transmission whine when its at the end of its life or a car audio engine noise whine almost. Its hard to hear with the window down and very faint from the engine bay. This is the list of things Ive done to try and solve it by myself.

-I do not have a radio in the car or any speakers in the car
-Ive lifted the car on jack stands and left it in gear (1st and 2nd) and listend to both sides of the transmission for layshaft possibilities and could not confirm any noise there
-The car shifts like normal and does not pop out of gear nor does the shift lever move any
-Clutch depressed at idle, no change so its not a clutch release bearing
-Its about the same pitch if I accel or decel in gear
-In gear while driving at any speed you can hear it and it really dosnt change pitch, if you depress the clutch while driving (neutral) the sound almost disapears. It is rpm related.
-Changed the transmission fluid to redline and engine oil when I bought the car, old fluids looked great.
-if at idle or at speed in neutral and you rev it you can hear it, sounds like a timing belt or drive belt that is to tight.
-battery was checked to be good and holds 13.1 volts. When running the alt puts out 13.8v which to me is on the low side. I thought it might be a alt tensioner or alt bearing but have not listened in those areas to confirm


service history is good since new
belt service sompleted 2.5 years ago by a well know shop in the area prior to my purchase along with misc fixes.
no clutch change history but no signs of leaking or slipping and has good pedal pressure

so parked reving you can hear it and while coasting in neutral and reving you can hear it. Is this just a normal fcar noise? It to me sounds idler or belt related, I just want to rule out the transmisison.

anyone have similar stories?

 

I dont think it has PS and i would think it would be an electric pump if it were not belt driven. Its definatly coming from behind the seats. Even parkrd in the garage reving it yhe sound is presant.

 

it dosnt seem to matter if the clutch is in or out/ at ilde or speed in nuetral, just rpm related. If im at idle and rev it you can hear it same as if you were driving in gear or if you put it in neutral and coast then rev the engine. I just notice it in gear becuase of a constant rpm. The higer the rpm the more you can hear it.
Im wondering if its the engine placement. Im a Toyota MR2 guru so im pretty fimilar with mid-engine cars but not with the belts againt the firewall. I just want to know if this is normal. On some higher hp turbo honda's I would use a mechanical t-belt tensioner and tighten the belt to prevent timing loss (due to the hydralic tensioner often would fail) and the belt would make about the same noise.
How do you remove the inspection cover for the t-belt. I assumed it was all one piece.

 

Im guessing if I do have a problem it will be belt or tensioner/idler related.
Does anyone else have similar noise when driving their car? Perhaps this is normal noise and Im chasing a ghost.
The inlaws are in town so it will probly have to wait till this weekend to work on the car. Im going to start by removing the alt belt then the ac belt to see if one or the other is the cause of the noise. I will also remove the timing cover (I assume it is a two part cover)

I dont think but I dont know if the rear bearing in the clutch cover would be the issue. I dont hear any noise back there and it dosnt seem to change with the clutch in or out. Does this bearing have any different pressure if the clutch is in or out or is it simply a shaft bearing? From the pics Ive found it looks to me that it is just a shaft style bearing so pressure should not affect it. RPM would though which is the problem Im having but I dont seem to hear anything bach there.

Thank you for all your input.

 

The gearbox oil level is good, and has fresh fluid with no debris in the oild fluid.

The sound is present when reving the engine. Either at a stop or while coasting. It dosnt matter if the clutch is in or out in gear or not. It is just based on rpm.

If the problem was in the tranny for whatever reason I would think that the sound would come and go depending on if it were in or out of gear but mine does not.

Let say im cruising at 40mph and I can hear the whine sound, then I push in the clutch and coast while in gear. The sound almost disappears. Then with the the clutch still depressed I rev the engine the sound comes back, up and down with the rpm change. If Im still coasting and let the clutch out in neutral now then rev it, it still does the same thing. The sound comes and goes. Weird.
At a complete stop in nuetral and I rev it its the same sound. Its definatly rpm related, but since it does it at a stop Im trying to rule out the tranny. I know even at a stop the tranny still spins so I guess it could be the tranny. Ive never had one apart to see how they work, just going on pictures.

Its kinda like a supercharger belt sound but nowhere near as loud as the charger it self or as high pitch. Almost sound like a buffer when you first start it.

 

I plan on looking at all these things better this weekend.
The ac compressor only spins internally when turned on but it could be the ac pulley/clutch.
I wil remove both belts to rule out all the tensioners ect.....
The timing belt idlers and tensioners where changed with the belt roughly 2k kiles ago.
I will look into the oil pump bearing idea. I never noticed it before so ill have to find a diagram online.
Thanks for the input.

 

WOW! what bearing is that?

 

okay I just pulled off the drivers upper timing cover, all looks normal. The belt guide on the top side is not rubbing the belt either. The gear side of the belt looks good also, no signs of rubbing anywhere. I pulled the alt out and it spins good with no play. Im going to have it tested tomorrow to make sure its not whining on the bench with a load on it while its out. The tensioner has no lateral play in it. It does not free spin or feel loose, more like a new timing belt idler or tensioner bearing would. I dont know if they are supposed to be this tight. It does not feel rough when it spins either. Im going to drive it maybe tomorrow around the block without the belt on to see if the sound is gone. I still have the ac belt on to rule them out one at a time so if it is a belt Ill know which one it is.

I tried to get on the racambi website to look up the transmission oil pump bearing but I couldnt find it. Also someone said engine oil pump bearing but I didnt really see that either. Anything else I should look at that is a normal problem on these cars?

I did notice while under the car the plug on the tranny is a little wet. Not the allen drain plug but the large plug next to it, maybe a 22mm hex head. Any idea what that is? I dont want to pull it out to put a new gasket in if its something Im not supposed to pull out, like the engine oil pump relief spring bolt.

thanks

 

After removing the belts one at a time there is no difference in sound. Ive determined it is just the sound of the timing belt being directly behind the seats. I cant hear or find anything else that is making noise. Maybe its just loud because its such a long belt.

Thank you for all your input.

On another note, what is the plug next to the transmission drain plug? It is a hex bolt not the allen bolt, its about a size 22mm in front of the transmission inspection plate.

 

The belt and tensioner ect were done in 09/2010. I would imagine they would last that long. They are factory part numbers on the bill so I assume they were changed. The timing belt appears to be in good shape from what I can see from the upper inspection cover. When Its running I cant really hear anything from the bottom of the car (its so loud under there).
The sound of the noise is very faint. It sounds like a belt that is over tight or like the sound a power steering pump makes when at idle and the wheel is at full turn on a ps equiped car, but not that loud. Just the same pitch. Its very weird. I just thought perhaps the timing belt was adjusted to tight.
Can anyone else hear the same noise on their cars? Its very hard to listen for though.