Whining sound, very specific conditions

[romaniuk]

I started hearing a whinine noise while driving down the highway, mainly under acceleration or going up hill. It's only in 5th gear, and only at 110km/h (~70mph). It's silent up to 110, then I hit 114+ and it goes away. Fourth gear and lower don't do it all, either at the same RPMs (so it's not engine) or the same truck speed (so it's not the drive shaft). Any ideas? I'm guessing my 5th gear is starting to crap out and I'm just gonna need a new tranny when it finally goes.

 

[MAKG]

I doubt it; transmission whines aren't usually that particular about speed. A more typical transmission whine would gradually fade in at a given RPM in one or more specific gears, and isn't likely to go away. But change the fluid for a "tell." Pretty and red = good.

 

[romaniuk]

I just had the fluid changed in the fall, actually (not sure what it looked like, but apparently it "looked fine").

 

[MAKG]

It doesn't matter. When in doubt about your transmission, change and inspect the fluid. Period.

When your transmission "craps out," you may lose much more than 5th. Can you tolerate being stranded at a random time? Most people can't. Places like remote highways or the middle of urban freeways are not good places to get stuck.

 

[romaniuk]

That's a good point. I'll have to check it.