1989 4Runner V6 making "clacking" sound

I'm not real familar older Toyotas but I'm trying to solve a interesting problem with a 1989 4Runner. The accelerator got stuck and the motor redlined for a brief moment or two. Ever since then, there's been a "clacking" sound when there is a change in RPM, accelerating from idle or returning to idle. There's no sound when it's just idling and it seems to have normal power.

I'd like to know what is the cause of the noise. My guess would be some part of the valvetrain but I'm more of a pushrod guy so I'm not exactly sure what goes wrong in these motors. Any ideas?

Beans Baxter

Reply to
Beans Baxter
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Visually inspect the timing belt: if aging, it may have skipped a tooth, or may now be slipping under hard acceleration.

Could be a external component or bracket knocked loose and physically striking something else. Visual inspection.

Could be stressed bearing or burned valve. Try an oil change, and if fresh (consider even heavier for this change: straight 30 or 10w40) oil quiets it down, you know it is an internal issue. At that point, if you're worried about it, have the head or the lower end redone; if not worried about it, drive it until it becomes a real problem.

good luck! GTr

Reply to
gregory trimper

I'd speculate piston slap, but can't see how a short time at high rpm would initiate that. The noise only occurs coming off or going onto idle speed?

-paul

Reply to
Paul Cassel

Take a tube of solid material, metal is best, but hardwood will work. place the far end on the head, then on the block, thumping is good, ringing is bad.

Reply to
?reality

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