SM 465-Bad Noises

I would guess differential also. Here is a trick I've used in the past.

Take a small tape recorder,using duct tape,mount it to the driveline component,where you think the noise is coming from.

Go for a short drive,then mount it on another driveline component,go for a ride.

This should help you dial in the noise. Good luck!

 

Thanks for the replies. It's very definitely coming from the transmission or transfer case. The truck doesn't have any sound insulation so all noises come through clear as a bell and it's easy to tell where they're coming from. I'm used to the normal transmission sounds, the new noise is just a lot louder than I'm used to. I think it would actually be best described as a screeching or squealing.

Today I determined that it only happens when the transmission is cold. After driving for a couple minutes it won't happen. I also checked the oil level and it is a bit below the fill plug on both the tranny and transfercase. I bought some lucas oil stabilizer and I'll put it in tonight. Hopefully it'll help. I'll update if anything changes,
thanks again,
dh

 

Here's an update. I thought I had it figured out, but now I'm worried again.

It was only happening when the transmission was cold and in high gear, ok, no problem. I let it warm up before I went into high gear. That seemed to be ok and I didn't hear "the sound" for a few days. Then today it came back. I was on the freeway cruising at about 60 mph. The transmission was good and warm (I figure) because I was driving for about 30 minutes before getting on the freeway. After about 5 minutes on the freeway the noise starts. I've noticed there is a quiet clunk sound when the screeching starts. Then there is the same clunk when it stops. When it's making the sound I can sometimes get it to stop by letting off the gas. Then when I get back into it the sound comes back. I was in traffic today and couldn't do much accelerating/decelerating to try to get rid of the sound. After squeeling for about 30 seconds it started to make bad clunking sounds and make the truck stumble. It felt like an engine miss but it wasn't the engine. The transmission was catching up and making my truck kick and stumble. This happened for about 30 seconds and then it went away and was fine. I've since driven it about 50 miles today with no problems. I figure the screeching was a bearing heating up and the kicking was it grabbing. Does that sound plausible? Does anybody think this could be something else? What would screech so bad then go away? I was planning on putting synthetic oil in it but now I don't know. Maybe I'll try it anyway.
thanks for any help,
dh

 

Maybe the throwout bearing is squeeling? Adjust a tad too tight?

Would this happen in only high gear? It seems to be gear (or output shaft speed) dependant.