A bit of background: I recently bought a 1987 4runner off clist. It's running OK, though not too powerful, and it has a fairly rough idle.

I notice that when it is idling (and probably when not idling) , the engine makes a strange "compressed air" sound, like its releasing a puff of compressed air on every revolution. I made a video of it @ https://goo.gl/photos/tjcJbdnFiaTkCrC68 , you hear its like a periodic "tssss" Any ideas of what this could possibly be?

There is also a clattering sound as you can hear. Could this be due to incorrect valve clearances?

Thanks for any and all advice

 

Yeah, sounds like your valves need adjusted.

As for your "tsss" sound, that could be a result of valve adjustment, an exhaust gasket or may be an issue with the PAIR system.
PAIR = pulse air injection reaction.

 

Thanks greatly!

Is the PAIR system what's indicated as "AS reed valve" in this diagram?
http://i5.photobucket.com/albums/y16...Toyota22RE.jpg

 

It's a little difficult to tell from the video but that clattering noise sounds like your timing chain has wore its way through your chain guide and is now slapping the inside of the timing cover. I would take the valve cover off and check the condition of your timing chain guides.

 

Well, I figured out the compressed air noise --- one of my spark plugs was loose!

Unfortunately, 100 miles after fixing this, the timing chain snapped. Should have listened to @85TRD4runner probably.

Also, the plastic timing chains are destroyed. I suspect this 22re possibly went 320k on the original chain/guides.

Arrrr.

I assume the valves are bent up. Do the pistons usually come out of this ok?

 

If the valves didn't break/drop, the pistons are probably fine. Might show a little dent from kissing the valves but probably no real damage. If you have any raised metal slivers from the impact it might be worth smoothing them out but other than that, run it.

 

Thanks @arlindsay1992 .

Once I get the head off I will take a look at the damage done.

 

What you'll want to look for is a bent valve.