Squealing bearing

[investig8]

Hello Everyone,
Well, took Fiona for about a 15-20 minute drive this morning and find that I have a bearing squealing at higher RPMs, about the time to shift. It sounds almost like a throwout bearing, but it is doing is in neutral and when driving, and with the clutch in or out so I don't believe its the throwout... any suggestions that I could check?
thanks,
Dennis

[Elwood]

Hello Everyone,
Well, took Fiona for about a 15-20 minute drive this morning and find that I have a bearing squealing at higher RPMs, about the time to shift. It sounds almost like a throwout bearing, but it is doing is in neutral and when driving, and with the clutch in or out so I don't believe its the throwout... any suggestions that I could check?
thanks,
Dennis

By "..it is doing is in neutral..." do you mean that the noise is evident when the transmission is in neutral, the clutch is engaged, and the truck is not moving, or only when the transmission is in neutral and the truck is coasting?

You might also check for the noise when the truck is coasting and the engine is off, with the clutch engaged and the transmission in neutral, and with the clutch disengaged and the transmission in a forward gear (do not do engine-off tests for extended periods of time, as the transmission counter shaft needs to be rotating for proper lubrication)?

It's not impossible that the throw-out bearing is toast, but it could be the transmission input bearing.

Have you checked the transmission and transfer case lubricants for level and condition?

[PoW]

The number 1 squealer bearing will be in your generator/alternator.

In an M37, they spin up to 8,000 rpm at road speed.

PoW

[investig8]

Generator is where I was guessing, this one has a rebuild tag from 1969... it's probably ready for some maintenance
Thanks