No, I've had the tires for the past couple of years. It still has quite a bit of tread on it, Like I said I don't drive it much. Only if I need to haul something large like furniture or if I don't have the neon and need to make a short run somewhere.

This is definitely mechanical, this was a new sound that appeared about a month and half ago. Tires don't make this kind of noise, it's a well defined groan, not a whirring or wurring sound. The groan sound is very short like a second or so this occurs around 5-15mph, sometimes longer if you're going up a ramp or doing a hard accel from a dead stop it also does it randomly, but my test drive tonight it no longer does that. If you feather the throttle at 30 you can make it consistent, but it's faded and not as strong. Going up beyond 50mph is pointless, since it doesn't do it.

I noticed there's a bushing at the beginning of where the drive shaft couples with the transmission, the drive shaft is above this bushing and there's a V shape like frame going towards the van with this drive shaft in the middle. It sits horizontal if you're looking from the back end towards the engine block. I wonder if the drive shaft is rubbing again this.

 

Even though the u-joints were replaced in 2002 and the driving has been limited, the newer u-joints can still go bad. A buddy of mine with his Jeep CJ7 went through a new set of u-joints in one year. He bought a different brand the second time around and those have held up for over five years now.

For the rear oil, Chrysler has a TSB mentioning that 75W90 synthetic is ideal for improved fuel mileage on our vans. http://dodgeram.info/tsb/2000/03-08-00.htm

Also, you had mentioned that the old rear oil had a whitish tint. Here is the reason Chrysler mentioned for rear wheel drive vehicles, "The cause of the milky-like appearance to the axle fluid may be due to the use of a white color gear marking compound during the axle assembly process. Axle gear marking compound is used to verify correct ring and pinion gear alignment during manufacture."

 

I will get under the van tomorrow and check the u-joints for play. Should of done it today when I had the chance but I was busy. I just look on advanced auto and they have three. One for 10$ another one 12$ both by neapco and 17$ one by brute force.

Reading online on how to replace them doesn't seem hard, just needs some TL *tough love.* am I turning into a gearhead?

Remove driveshaft, Remove snap ring, pop the bearings out, remove joint, insert new joint, pound new bearings back in and place snap ring back on, reinstall driveshaft.

also how much of an influence in gas mileage can I see if I went to 75w, even tho I already have 80w in now? I feel that it may be negligible, like maybe a mile more?

 

Tires can make the noises you speak of, even with plenty of tread. Many people trade in tires with plenty of tread just because they are loud. Try a tire rotation as an experiment and see if that changes the tone and speed at which it occurs.

I swapped my 8 3/8 axle(what you have) with a 9 1/4, and had to use a conversion U joint on the rear, because the Yoke on the 9 1/4 was bigger than the 8 3/8.

You wont notice any difference between a 75w 90 and an 80w 90. At full temp, they are both 90 weight oils. The 75 just is a little more fluid at lower temps.

 

Ruled out tires, I put my left foot on the break real good, put the right on the accel, still got the sound even though I wasn't moving. check the U-Joints they seem solid, greased them with a grease gun. Sound still there.

But while I was under there I noticed that the transmission mount on the back is shot to hell, and the transmission is not sitting evenly. Could this be my problem? Could the transmission be vibrating to the bushing which is metal on metal.



Gonna replace anyways, see if that resolves my issue?

 

Possible on the transmission. If it is loose enough the back of the transmission will vibrate and put undue stress on the motor mounts.

 

well replacing that bad mount didn't help.

This has got me, I don't know what it is, if it's the transmission or the differentials. I pull off each tire and drum to see if anything of interest was there and check the wheel hub for play. It felt solid up, down, left, right but just a tiny bit *about less then millimeter* of play being pushed and pulled, I feel like this is normal for an axel.

I tried shifting to neutral to see if the sound persist but it doesn't last long enough to determine if the tranny is the problem or not. Tried driving around on low gear, still does it then tried 2nd gear, results the same. But I can't seem to make it happen on cue. But if I put my brake on and accelerator at the same time while in drive and get the engine high enough I can make it happen without going anywhere.

The only thing that has alot of play is the output shaft of the tranny and input shaft of the differential even tho the u-joints feel solid and don't make any noise.

If anyone got any ideas of what's going on? let me know, otherwise I think I will drop it for now, drive til it breaks or drive til it dies.

 

My tires were quiet when new and now that they are older they make noise like the previous set.

 

Never disputed good practice, just said it wasn't a major emergency. Chill out.