New engine noise (not valve tap or chain rattle)
 

We just got a couple inches of new snow yesterday and I got stuck goin' around a corner. Had to hold WOT for about 30 or so seconds, rev limiter kicked in and all to get unstuck. Now I have a dull rapping sound under my valve cover. It's not the usual valve ticking or timing chain rattle, I already had those and they have a more "metallic" noise, it's a little sharper of a noise than I hear now. The noise dissappears under load but returns when cruising @ 2500 rpm in any gear, or when letting off the throttle to shift gears but dissappears as soon as I put the engine back under load, or until I hit 2500 rpm again. It's still there @ idle just not very pronounced, until I rev the motor. I also noticed a sizeable amount of oil leaking out between the valve cover and the head on the exhaust manifold side of my #4 cylinder. Does anyone have an idea? Bent valve, cam bearing, valve seal? Help!! :help:

This sounds strikingly familar to what happen to my buddies truck. The truck got a little warm, and I think warped the head or blew the headgasket. Started profusely leaking oil like yours (near the back of the motor). Winded up with a bent valve, a hole in the number 4 cylinder, coolant in all kinds of places coolant shouldnt be (oil, cylinders, intake), and some other random things that never made sense. But no real proof as to what caused the whole thing..... ended up rebuilding it and it still is a little off (but it think the wiring harness is shot for noticable reasons) I only hope your truck isnt doin what my buddies did, and my buddies truck still ticks me off, cause i have no idea what went wrong first (when a head gasket blows does it shoot oil out the back????), and why it started shooting oil out of the back of the motor (which was the first sign something was wrong, followed by a bang (hole in piston) which signaled the end of the motor)

but, it kinda sounds to me on your truck, like a broke chain guide causing the chain to rattle..... can you pinpoint its location using a screwdriver to the ear method?

The noise is definitely coming from under the valve cover. It's not a rattling sound, or ticking, but more of a solid rapping sound. It sounds like its coming from above the number three cylinder. Also I forgot to mention that the truck (after warming up to operating temp) idles lower now and kind of rough, and almost feels as if she's gonna stall sometimes when coming to a stop. I guess I'll have a peek under the valve cover to see what's going on. Thanks for your input colsoncj!

Could be a camshaft.... just throwing ideas out, but its possible that the cam could be givin you problems, maybe ate part of a lobe and the rapping sound is the cam slapping against the bucket.... worth a look. Id say go with the plan of yankin the v/c off and take a look, post what you find out.

sounds just like my rod bearing did when it started gong out, no noise under load, but when i backed out of the throttle to when there was no load on it thats when i heard it

Thanks guys, I'm gonna try to make some time this weekend to have a look and hope it's nothing too bad. From what I can tell, these engines are pretty agreeable to work on anyway! I'll post more info when I get it.

New engine noise
 

Toyotaman: I just bought a 1989 4runner for my son and it just started making the same type of noise. 3.0 V-6 with 130K miles, I will pull the valve covers this week end and I would appreciate hearing what you found as well as any suggestions from other members. I am new to Toyota and may have to hook up with a good Toyota mechanic up here in the northeast if someone has a recommendation I would appreciate it..Thanks, Greg.

New engine noise
 

I just found the right side camshaft out of time by one cog. The belt was loose. I will post whether or not this cures the noise after I reassemble later today.. Greg.