Is it transmission or differential noise?

[Doug Rodrigues]

Re: 1992 Dodge Ram Van B350 318ci engine. Took it for a test drive today, prior to buying it. Sounds like a rear end noise…sort of like the old motor driven sirens on old fire trucks turning very slowly at a very low tone. The noise only occurs from zero speed to about 25 mph. The noise becomes quieter the faster you go, and the pitch of the tone also rises as you go faster. If the transmission is shifted into neutral, the noise disappears. I’m not sure if it’s the rear end or the transmission? Is this a typical problem with the Dodge Ram Van with transmission or rear end problems? Does anyone have any idea what it probably is? I think it’s the differential, but not 100% positive about that?

[alloro]

This is odd because a tranny or rearend whine will usually not go away. When you shifted into neutral, did you by any chance rev the engine to see if the noise reappeared?

[Doug Rodrigues]

Not an engine noise...a drive train noise. If rolling slowly at 25 mph and the transmission is put into neutral, the noise disappears? The guy who is selling me the vehicle said that sometimes the noise disappears for a while, then returns days later.

[pmpmrs@amigo.net]

Originally Posted by Doug Rodrigues

Not an engine noise...a drive train noise. If rolling slowly at 25 mph and the transmission is put into neutral, the noise disappears? The guy who is selling me the vehicle said that sometimes the noise disappears for a while, then returns days later.

My '02 ram van 3500 made the same noise. Whined under acceleration and stopped when I coasted. Found out it was the wheel bearings on the left side. Fixed it with good napa bearings, some time ago.
mike

[Doug Rodrigues]

Okay, I'll go pick it up on Wednesday (from out of State). I'll have someone drive it while I stick my head out the left side and right side rear windows to determine if that noise is obvious from either side. Thanks for the information.

[alloro]

Originally Posted by Doug Rodrigues

Not an engine noise...a drive train noise.

The input shaft bearing, torque converter, or pump for the tranny are drive train items that follow engine speed, not vehicle speed. I ask questions to try and narrow down the problem, not to just waste your time or mine.

[Doug Rodrigues]

Turned out to be the right rear axle and wheel bearing. With the half ton and three quarter ton Vans, the axle itself functions as the inner race for the wheel bearing. A small chunk of metal was missing out of the machined surface of the axle. Everytime the axle rotated and made contact with each roller bearing in the race, it produced that low pitch siren sound. Unfortunately, after replacing the axle and wheel bearing, now the ring and pinion gear sound that was convered by the wheel bearing noise is audible. Crap!!!

[Doug Rodrigues]

I forgot to mention, until the axle got pulled out, I thought it was a B350 one ton. Turns out to be a B250 three quarter ton.