The "clank" noise from the engine compartment and underneath the vehicle (1988 4Runner, v6 3.0, 5spd) is becoming persistent in the past few days. So I had a weekend off trying to pinpoint the source of the problem. The thing I noticed was when the engine idles with tranny in neutral, the clanking noise continues even though when the engine was warmed up. Once I pressed the clutch, the noise stops and the engine idles perfectly. So I had my wife sit in the 4runner and started the engine - clanking noise resumes with tranny in neutral. I had my wife just pressing the clutch in, the clanking noise disappears and I rev the engine to see if it knocks or whatnot. The engine idles perfectly.

What are the possibility that causes the clanking noise?

Toasted tranny?
Throwout bearing in dire need of replacement?

I will drain the tranny oil and see if theres any metal shavings or debris to determine if the tranny is toast.

Is there a possibility that the xcase is toasted as well?

What say you fellas??

 

if as you say it disappears when the clutch is pressed then yes the throw out bearing is toast. The clanking noise is more than likely it is loose in the arm that carries the bearing.

 

Grab the release fork, and see if it is properly set against it's pivot. Try and replicate the sound by wiggling it back and forth. If you get somebody to operate the clutch while you're underneath again, have them barely push the clutch pedal, and see when the clanking stops.

If it was the throwout bearing, why would it stop making noise when it's actually being used? That doesn't make sense. And usually a bearing will not make a clanking sound and still work. If a bearing is clanking, it is completely destroyed / grenaded, and will not function at all.