Drive Train "Whine"

[WVBill]

My 2000 Dodge Ram 1500 4WD with 110,000 miles has developed a "whine" from somehere in the drive train. The whine starts at 45mph, peaks at 50mph and is gone by 55mph. It is most pronounced under slight load/accelleration and goes away completely and instantly if I take my foot off the gas.

Any ideas where I should start looking for the cause?

[yellowyj]

I would check the universal joints first. Check them to see if they have a lot of play. If they are in good shape grease them up good if they are not too dry.

[egon]

If there is a center bearing it may be worthwhile to look at it too.

Egon

[CJDave]

If that vehicle has a manual shift transmission with overdrive, I would suspect that first; and then after that I would think about the pinion bearings in the rear end. [img]/forums/images/icons/crazy.gif[/img]

[WVBill]

Thanks, guys. It's an auto tranny - forgot to mention that.

I'll check the U joints. Egon: how do I check the centre bearing - just check for play by trying to move the drive shaft?

Thanks again.

[egon]

Bill:

Checking for play or feeling it for heat after driving is the only way I know of.

Egon

[Autotech]

Some questions:
Does the noise respond to acceleration/deceleration? Noises affected by drivetrain loading are generally due to wear in the differential, most commonly the pinion gear or bearings.
Does the noise have the same behaivior if you hold the trans in a different gear instead of allowing normal upshifts? This can help indicate if the noise only occurs in a certain gear - if so it's most likely in the transmission.
U-joints usually click, thump or squeek - rarely whine. Look for play across the cups (not inline) or rust coming from the needle bearings.
The center support may be the culprit also - look for play, or rust coming from the bearing.
Of course, you HAVE checked the trans and diff fluids.....?

Gregg

[WVBill]

Thanks for the help, Gregg.

Yes, the noise responds to accelleration/deceleration. It is there only when when accellerating/holding speed. It is not there when the gas pedal is released. In addition, the "pitch" of the whine increases with the speed.

I'll check on the way home today whether the noise is affected by the gear. Since the noise is only there between about 45 and 55 mph, I likely will only be able to check Overdrive on and Overdrive off - I don't know if I'll be able to get to 50mph in D2.

The trans fluid has been checked and is OK.
I had the diff serviced per the service schedule a while back but not since I started noticing the noise. I'll check it.

I'll crawl under the truck tonight and check the U-joints and center support.


Two people now have mentioned the pinion gear or bearings - I don't like the sound of that.... [img]/forums/images/icons/frown.gif[/img]

Thanks again.

[egon]

Not trying to be silly as had this happen to me but is there anything on the vehicle that could create a noise like blowing across the top of a pop bottle. Say an open end on a roof rack or some such thing.

Egon

[CJDave]

[img]/forums/images/icons/crazy.gif[/img] I once bought a '57 Shivel-A business coupe dirt cheap because the "rear end" was "kaputzo". It turned out to be a RF wheel bearing [img]/forums/images/icons/crazy.gif[/img] The gears were fine, but in that tinny, no-frills; not even a carpet, only rubber floor mats; body, the sound telegraphed nicely. A professional mechanic judged the car to be in need of a differential so the city of San Francisco wholesaled it out and I got it for a work car. [img]/forums/images/icons/laugh.gif[/img]