Loud Rattle in 1st Gear

[marvin2]

Driving to work this morning, the truck developed a loud "rattle" in 1st gear. The rattle builds with the rpm's, but then stops when I shift to 2nd (no sound in 3rd either). I can take off in 2nd gear without any noise as well.

Transmission is a 3 speed, column shift. I crawled under the truck and could not find anything loose and driveshaft did not have any play in it.

Any thoughts / suggestions would be greatly appreciated. Thanks guys!

[sargentrs]

Throw out bearing? A lot of vibration in first that's not present in 2nd-3rd. Any way you can isolate whether it's coming from the bell housing or transmission?

[marvin2]

I couldn't quite tell where the sound was coming from. I was hearing it out the back window, and it almost sound like it was coming from under the bed.

[chad67]

Does it do it coasting in 1st, too?

[marvin2]

That's a good question...my assumption is yes, but I will need to try it. I seem to remember a "ticking" sound as I was coasting through my subdivision last night.

[sargentrs]

I just remembered something. My truck would make a lot of racket in 1st or slowing down coasting. Pulled over and crawled under. The carrier bearing was hanging by one loose bolt, the other missing completely. I guess as long as the drive shaft was spinning rapidly, it stayed in line enough but when I was going slow, it started swinging.

[marvin2]

Just figured I would give a quick update since the fix turned out to be so simple. After grounding my truck for 6 weeks and convincing myself that the transmission was toast, I finally crawled under it today to change the trans fluid. I pulled the drain plug and maybe 6 oz. dribbled out....I couldn't believe it. I topped it off, drove it around some, and the rattle is gone. Judging by the mess under the truck, I obviously have a leaky seal(s) to tend to, but at least the truck is operable again.

Figured this was a good lessons learned to always start with the obvious when troubleshooting...