Driveline noise- Whirrring when you get over 40 MPH and varies as you increase and decrease road speed

Subject: Driveline noise- Whirrring when you get over 40 MPH and varies as you increase and decrease road speed
no the engine RPM.

I have a concern that as I am at 40 MPH and up I have a consistent Whirring Sound that is
varied somewhat with the road speed.

It sounds to me like something in the Transmission or an axle bearing.

I have changed the Rear Diff fluid and the old fluid came out clean as if it was
not original.

There was no debris in the oil.
the amount of old oil turned out to be EXACTLY the same as what I was able to put in
so I think the level has been good.

I can change the U Joints cheap enough.

I am not sure if my noise is in the Transmission or the axle.

Usually Tires sound a little different when they are funky and have a broken belt for example.

Does anyone have an transmission stories to share that would support my concern
that it is in the transmission ?

I may have to drive the car cross country ( 2200 miles ) and I would like to give myself the best
chance to succeed if that trip happens.

My car is a 1996 Roadmaster Wagon , non-towing equipped
and never had a tow hitch on it either.

( I checked underneath )

In other news does anyone have a line on the heat shields for the plastic gas tank ?
Mine are loose due to the little mounting tabs cracking off.

Best Regards,!
Shrimp

It’s too soon to panic, check out some easy & cheap things first. Jack up one side at a time, and rotate the tires front to back. Shake the front wheels, make sure your wheel bearing aren’t loose. Re-test drive, and see if the noise ‘moved’ or sounds different. Does the whirring noise stop when you (carefully!) shift into neutral over 40mph? Does the sound change ‘pitch’ if the road curves left or right? If your car has 150k on original wheel bearings and u-joints... might be a good idea to replace anyway

I would just wrap the pipes with header wrap anywhere near the tank.

Whirring that changes with speed is probably rear end gears, or bearings. Universals would not whir,  they would rattle or clunk. Since you had the cover off to drain the rear, did you check the magnet on the cover? If there is any grease on the inside of the backing plates, you probably need axles, bearings, and seals. 

My first guess is still the rear gears.

Further Diagnosis :

I kept at my testing.
If I am going 40 MPH and the sound is occurring ( which is continuous ) I can stop it by shifting the transmission into the Neutral position. In that position the noise is completely stopped but car is still moving. Then in Neutral I can accelerate the engine with the gas pedal and there is no unusual sound from engine or the accessories on it, such as A/C or power steering pump.

If I shift back into Drive then the noise immediately returns.
I am thinking it would have to be something at rear of the transmission such as the last set of bearings or possibly the first U Joint.

Any further ideas appreciated!
Shrimp

It could still be your rear. When the gears are not under pressure, they can go quiet. Is the noise under acceleration, deceleration, or both?

I'd even suggest checking your U-joints on the driveshaft. Had a similar issue on an '03 Suburban and it was my rear U-joint.

Best of luck!

-Michael

Sounds like the gears do in my Corvette. Someone forgot to fill the diff with oil right before I got the car.

In gear, let off the gas, does it still make noise?

RedandBlack wrote:

Sounds like the gears do in my Corvette. Someone forgot to fill the diff with oil right before I got the car.

In gear, let off the gas, does it still make noise?

That's a really good idea. Change the rear diff oil and make sure to dump in a bottle of GM Limited Slip additive. Might get lucky!

Try running in D instead of OD and see if the noise goes away. In 3rd gear everything inside the transmission is locked together and there's no planetary gears spinning. In 4th (and all other gears) the planetaries are moving; sometimes the rear planetaries don't get enough lube and they'll wear out and start making noise. It's rare but I've seen it.

First , thanks to all who have spoken.
Second- I am going to take some time Friday and try these ideas on level ground.

third- I am going to buy some 75-140 Mobil 1 gear lube and change over to that
and see if it is at all related.

More news by Monday.
fourthly- I hurt my left 3rd finger bad dropping my trailer tongue on my finger! But I got a
1994 Roadmaster 4L60E ( verified by the sticker ) for $ 100. It does not have any external
PCM stuff on it. So I am going to research if the thing will handshake with my 1996 or not.
If not, I have a very nice "core" for a transmission swap.
Shrimp- finger gimp!

The 94 has different internal electronics from the 96.

sounds like I have a nice 1994 tranny to trade for a 1996!!

shrimpNE wrote:

In other news does anyone have a line on the heat shields for the plastic gas tank ?
Mine are loose due to the little mounting tabs cracking off.

Best Regards,!
Shrimp

Bring the heat shields and any tabs that are broken off to a welding shop.  They can braze them, I had some of mine repaired 10 years ago.  Not impossible, but there hard to find in good shape.

Tom

Yes, repair and reuse the heat shields.

A '94 transmission will function in a '96 but GM added a TC lockup control solenoid in '95 and when the '96 computer goes looking for it and doesn't find it, it'll disable TC lockup.  Everything else will work fine. If you can find someone with JET DST or Tunercat OBD2, it may be possible to alter the programming so it doesn't care about that solenoid and then TC lockup will work fine too (look at just disabling the diagnostic check for the TCC apply solenoid). I would not drive on the highway with no TC lockup. The trans will run hotter and you'll be annoyed. Been there done that.

If you're adventurous you could swap the pump, valvebody and wiring harness and use the '94 transmission no problem.  You can do that with basic hand tools and a prybar (to pop the pump loose).  You will need new valvebody and pump gaskets but those are cheap.  Remove the wiring harness with a carefully positioned hoseclamp.

maybe we can take my car down the road and opine about the whirring sound

shrimpNE wrote:

third- I am going to buy some 75-140 Mobil 1 gear lube and change over to that
and see if it is at all related.

NOOOO! I have heard some horror stories about lack of adequate bearing lubrication running 75W140 in a diff designed for 80W90. 75W90 is ok.

My 95 was getting noisy, sounded like a tire. I Found a bad axle on the passenger side. I changed both bearings using axle saver bearings. U joints were stiff, went ahead and changed them also. Refilled with Royal Purple synthetic.
With the drive shaft and axles out, it allows for a thorough nspection of the pinion and carrier bearings, and you can eliminate the rear end from your list. If it's like mine , at 167k miles, it was due a thorough inspection anyway.
Changing the oil weight won't fix damaged parts.
I found a cracked heat shield also. Made some new tabs out sheet metal, tack welded them on
That's how I spent Saturday today. Good luck !

Has anyone got experience with having a repair shop replace the wheel bearings, the pinion bearing and the related seals ? Either good or bad experience. I am intending to find a qualified repair shop and have this done to my rear diff. It is a conventional diff. Not a Posi unit.
Thanks for any remarks or stories. I am gathering intelligence at this point. I am in the Rochester-Syracuse NY area.

When you did the differential fluid service, did you happen to remove the right side axle shaft and check the bearing race for wear?

No I did not. The fluid was in good shape. I replaced it with the 75-90 W. I will say the noice "Seems" to be from the right rear. I assume to check the bearing I have to remove the axle?

Can I remove the wheel an brake drum and attempt to lift the Axle Flange up and down with my hand ? does that tell me anything ? Thanks for your comment.

I had both axles on my 91 show significant wear, and there was no noise. They just started to leak gear oil into the brakes.

The axle may have a little play from the start, because you "assemble" the inner race when you put the axle in. If it has any noticeable play up and down, it is probably a worn out axle. There should be fuzz on the magnet on the cover plate if the axle is worn, because there is powdered metal in the oil.

You can usually find good axles in the left side of the differential in a junk yard car (wagon).

You should have someone listen to the noise from the cargo area of the car while you are driving. They may be able to get a better "fix" on the location.

If the transmission is having a planetary go out, you'll hear it in first and second gear as well. If it's just with vehicle speed, it's in the driveshaft or rear axle.

On my old 9C1, the axle wore enough that I could wiggle it up and down a little. Worth a check...