I am driving a '91 Toyota Pickup with a 22RE and a stock manual 5-speed. A day or so ago I heard a metal on metal rattle coming from what I thought was the exhaust (thought bolt was coming loose, forgot to thread-lock some). The other day I went under to fix it but nothing was loose anywhere I could see. So I turned the engine on to find the rattle, turned out to be coming from the transmission. I think and hope it is just a sheared off gear tooth from a bad grind (teaching girlfriend how to drive stick). The drive train has about 145K on it. Any advice?

 

Bearings. Check the drain plug for pieces/metal shavings.

 

What will happen if I leave it be?

 

when does it make the noise? All the time? When the clutch is in? out? Under load?

 

It makes noise all the time, less with the clutch engaged. I'm not sure about when under load because the sound of the exhaust over powers the sound of the rattle.

 

sounds expensive...

 

Did full inspection, no noise when clutch is not engaged (after cool down period of a few seconds, even if moving). Noise is constant no matter the load and is only there when clutch is engaged

 

Got a labor quote for $500 dollars not including cost of parts...