Transmission whine, Help please

[Chard10]

I have a 1968 c10 long bed. It has a 350 that was swapped into it sometime since then and possibly the original Saginaw 3 on the tree transmission. Lately the transmission has been making a high pitch whine that can be heard clearely in the cab and seems to come from the dash or underneath. It is not easily heard from the engine bay or underneath the truck but I assume it is coming from the transmission. It starts to make the sound around 2k RPM and up in all gears and it increases and decreases in pitch with RPM. It makes the same sound in neutral and in gear with the clutch disengaged (petal to the floor). Aside from the sound the transmission and clutch work great. No grinding noises, not harsh shifts, no slipping, strong clutch petal feel and engagement. If it were not for the noise there would be no issue. The transmission fluid was a little low, I put about half a quart in it to top it off and the sound remains the same. I have not noticed any burning smells or otherwise. I'm thinking it could be a bearing going bad (pilot bearing was my guess since it makes the noise with the clutch disengaged) and I would like to replace it before it damages the transmission if that is the case. Does anyone have any ideas? I will link a video below.

Thanks

[HO455]

Welcome aboard! Unfortunately I don't think I have good news. It sounds like you have a imput shaft bearing going bad. If you had to add a quart the transmission was at least half empty. It may just make noise for the next 10,000 miles slowly getting louder or it could seize at some point. Fortunately if you are going to change the throw out bearing you can do the imput shaft bearing at the same time.
If your not comfortable with opening up a gear box here is a link to gearbox videos. I don't know if he has a specific 3 speed Saginaw video but there are as at least 50 videos on his channel so you could find one. None the less watching the Muncie videos will give you familiarity with how they work and are assembled.
Good luck!

https://youtu.be/zqeatqmnW0c

[Chard10]

Originally Posted by HO455

Welcome aboard! Unfortunately I don't think I have good news. It sounds like you have a imput shaft bearing going bad. If you had to add a quart the transmission was at least half empty. It may just make noise for the next 10,000 miles slowly getting louder or it could seize at some point. Fortunately if you are going to change the throw out bearing you can do the imput shaft bearing at the same time.
If your not comfortable with opening up a gear box here is a link to gearbox videos. I don't know if he has a specific 3 speed Saginaw video but there are as at least 50 videos on his channel so you could find one. None the less watching the Muncie videos will give you familiarity with how they work and are assembled.
Good luck!

https://youtu.be/zqeatqmnW0c

Thanks, those videos look like great information! The reason I thought it might be the pilot bearing is because it still makes noise and is louder when the clutch is disengaged and the flywheel and input shaft would be spinning at different speeds. When it is in neutral with the clutch engaged or in gear it still makes a whine but is not as loud when the input shaft and the flywheel are spinning at the same speed and the bearing is doing less work. Does that make sense? An as for the gear oil being low, when I recently bought the truck I needed to change the oil, and the differential fluid as well, I don't think it had any sort of routine maintenance in many, many years lol. hope that helps.

[RustyPile]

Originally Posted by Chard10

.<snip>............ It makes the same sound in neutral and in gear with the clutch disengaged (petal to the floor)...........<snip>

Thanks

If the truck is sitting still during the above condition, it's not the transmission.. With engine running, transmission in gear, and clutch disengaged, Nothing inside the transmission is rotating.. If the noise doesn't stop when the clutch is engaged, it's NOT the pilot bearing as the input shaft will be spinning the same speed as the crankshaft.. My money is on a bad throw-out bearing....

[Chard10]

Originally Posted by RustyPile

If the truck is sitting still during the above condition, it's not the transmission.. With engine running, transmission in gear, and clutch disengaged, Nothing inside the transmission is rotating.. If the noise doesn't stop when the clutch is engaged, it's NOT the pilot bearing as the input shaft will be spinning the same speed as the crankshaft.. My money is on a bad throw-out bearing....

Thanks! That looks like the easiest to fix too so hopefully that's the one.

[Chard10]

Originally Posted by RustyPile

If the truck is sitting still during the above condition, it's not the transmission.. With engine running, transmission in gear, and clutch disengaged, Nothing inside the transmission is rotating.. If the noise doesn't stop when the clutch is engaged, it's NOT the pilot bearing as the input shaft will be spinning the same speed as the crankshaft.. My money is on a bad throw-out bearing....

It was the throw out bearing! I replaced it last night and the sound is gone, it also shifts much easier. It wasn't a difficult job at all, and only took 3 beers lol. Thanks for the advice!

[HO455]

Good to hear you got it solved and thanks for posting your success.

[Chard10]

Originally Posted by HO455

Good to hear you got it solved and thanks for posting your success.

Thanks!

[RustyPile]

YES!!! And thanks for posting that you got the problem solved.. Most of the time the "problem solvers" are left hanging, not knowing the outcome....

[Chard10]

Originally Posted by RustyPile

YES!!! And thanks for posting that you got the problem solved.. Most of the time the "problem solvers" are left hanging, not knowing the outcome....

Lol, i wouldn't leave you hangin'