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fighterpilot · 03-18-2013, 07:49 PM

Roadmaster R3100, 8/96, Allison 6 speed, Cummins 8.3 on a 1997 Monaco Dynasty 38 footer. At speed with some throttle applied to keep up speed have a loud whine in back bedroom just forward of bed seemingly about over the rearend. Let up on throttle goes right away quick, add throttle comes right back. When pulling away from stop sign and accelerating, no noise untill get up t0 50 mph or so and it gets louder on to to cruising speed at 70 where it is pretty much a steady and loud whine. With no noise at lower speeds and lots of throttle if it were the turbo shouldn't I hear it than? So is it most likely the rear end--does the tx. ever act that way? Help. Thanks

Mac99 · 03-18-2013, 08:13 PM

You need professional diagnosis.

Mr_D · 03-18-2013, 08:22 PM

Usually a ring and pinion gear worn or out of adjustment. Problem is, if it needs adjustment there really isn't any but spacers and that takes a rebuild.

fighterpilot · 03-18-2013, 08:44 PM

If it turns out to be the rear is it possible to find a used one from an RV salvage yard or should one just get this one rebuilt? Anyone care to take a guess at the cost either way? Thanks

EngineerMike · 03-18-2013, 08:58 PM

w/new replacement gearset in your rear end ~$6k for our rig, parts & labor
good idea to find used, google: "RV salvage" and you'll find places to call

TQ60 · 03-18-2013, 09:54 PM

Sounds like rear end.

Did you check the fluid?

Could just be running dry, check fluid, fill if low and see what happens.

It would need to be inspected to confirm condition, check with some truck servicers for advice there.

Mr_D · 03-18-2013, 09:59 PM

Quote:

Originally Posted by TQ60

Sounds like rear end.

Did you check the fluid?

Could just be running dry, check fluid, fill if low and see what happens.

It would need to be inspected to confirm condition, check with some truck servicers for advice there.

If fluid is low there has to be a leak, and if it's noisy then there's probably already damage done. Maybe you could pack it with sawdust and sell it quick, like the car dealers used to do!!

sc3283 · 03-18-2013, 10:28 PM

Pilot, none of us can hear the noise, nor predict the future...but I will say...many of the large rear ends do make some noise as you describe...and have gone thousands upon thousands of miles. While yes in the perfect world a ring and pinion won't make noise but occasionally 1 gear set does. If uncertain....have someone with knowledge listen for you...

Coaster1 · 03-19-2013, 06:22 AM

Mileage? Check the U-joints.

ahicks · 03-19-2013, 06:35 AM

Quote:

Originally Posted by sc3283

Pilot, none of us can hear the noise, nor predict the future...but I will say...many of the large rear ends do make some noise as you describe...and have gone thousands upon thousands of miles. While yes in the perfect world a ring and pinion won't make noise but occasionally 1 gear set does. If uncertain....have someone with knowledge listen for you...

X2

Even my pickup makes noise at certain speeds.....

fighterpilot · 03-19-2013, 06:42 AM

65,000 miles. Will get under there and check fluid. In this time frame did they use one name brand rear end? What should I look for to identiy it? Is there a tag on them like on cars? Thanks

Coma · 03-19-2013, 08:19 AM

Should be a tag with model and serial number.

GuidoDoc · 03-19-2013, 09:34 AM

Sounds very similar to the question I posted about front end engine noise in my brand new Seneca. Search "noise while cruising" for a few suggestions. Mine is diesel puller but Allison tranny and cummins ISB motor. I don't have an answer yet.

Ramzfan · 03-19-2013, 09:39 AM

I would check the rear-end fluid and then if that was OK, I would bite the bullet and take it to your nearest Freightliner or whoever built your chassis and have them do an inspection and estimate.