I seamfoamed my 1991 Toyo PU, 2wd 5spd 22RE few days ago. Ever since revving really high to get all the gunk and exhaust out, i've been hearing a scratching/chattering kind of sound. I heard it for the first time when i was idle at a red light..it was LOUD and very distinct. I revved it once and it died down. Since then I've been hearing it here and there. Never really at a specific time. Just spurratic times.

It sounds like its coming from around the intake...Could it be the MAS? I'm not sure though because I can never hear it when I'm under the hood. Only when I'm driving. What could i have broken by revving it too high?
I dont recall ever revving it that high before.

I heard that the timing chain could have busted one of the plastic guides..How can I test to see if this is the case? How much is the replacement for these including labor?

It hasnt affected the performance, but I hate the noise and want to get rid of it because it's not normal. Does anyone have any idea what this could be?

Drop your oil pan; if there's plastic pieces in it, you know what happened! i think you can also remove the valve cover & look down inside the chain housing.

I'm not due for an oil change for another 1,400 miles or so. If i drop the pan and get rid of the oil, can I just slap it back on and pour some new oil in?

I wouldn't since your at about the 3/4 mark as far as milage goes.

Just pull the valve cover off and shine a light down into the timing chain housing. It is easy to see. but you definitly want to check it out before it wears a hole in the water pump part of the cover.

sounds exactly like what my chain was doing when it was worn out. You wanna check that ASAP.

x2, valve cover removal is only 4 bolts and a couple hoses

Rob

A warn chain goes OVER time..There hasnt been any sign of it until i revved it really high ONCE.

Also, its not a constant or intermintant sound.