It might even be a valve train component just rattling — faulty rocker arm, collapsed hydraulic lifter, etc. I'm assuming that the rattle sound continues even if the engine is running minus the fan belt for a few seconds? perhaps the source of the rattle — if it is a valve train component — would be obvious if you observed the rocker arms in operation with the valve covers removed. A faulty rocker in operation would be obvious in comparison with the operation of all of the others.
The rattling sound sounds somewhat random in nature, like a loose component, rather thann the repeated, cyclic sound you might expect from a faulty connecting rod bearing, so something like that. A mechanics stethoscope might help you to pinpoint the source of the sound or where it is emanating from.
The video below may be an example of the continuous, repeated, cyclic banging sound you might hear fro a bad connecting rod bearing. It also seems directly related to the increase or decrease in engine speed...
It is hard to focus on the location from watching the video, but even in the video it seems like the rattling sound is more distinct on the left side of your engine.
If it were a loose timing gear, The sound would emanate from the center front of the engine, at the front of the oil pan. The large aluminum gear is a press-fit on the end of the camshaft,held in place by a Woodruff key. I remember seeing a video of a loose gear where the center hole was so damaged that, when observing the loose gear with the oil pan off, the gear could be rocked back and forth by hand. But your engine sounds like it is running smoothly — which I doubt it would do if the timing gear attachment was that bad.
Even a new lifter could be defective. The center of the lifter mechanism is a hydraulic piston that is supposed to maintain zero clearance in the valve train. If you adjust the lifter for zero clearance and the valve train clatter goes away, but returns again after a few seconds, doesn't that apper to be a faulty lifter?Going4joe wrote:...Jeff - hot valve adjust - do you mean while engine is running? If that is what you mean, than yes. Interestingly when the valves are adjusted this way, when you torque down on the valves in the #5 cylinder, the tap goes away for 5 seconds, then comes back. Torque it some more, and noise goes away then 5 seconds later, returns! All other cylinders respond to valve adjustment properly...
...Looking at the volume of posts from other Corvair owners on this site, and based on the experiences I have had owning them, these cars are a constant work in progress and are always needing attention somewhere. I think its great that you guys offer this invaluable service to those in need - people like me! Thank you for all your posts. I do eagerly read all that you contribute...
Properly maintained, I have found the Corvair to be a highly reliable car that does not require constant repair. I've been riding in Corvairs since I was 8 years old (1961), and my wife and I have driven them all over the USA and in Europe. They were my family's primary mode of transportation for much of my 24 years in the Air Force, and we had very few breakdowns on the road. But the cars are aging — well beyond their anticipated lifespan that GM engineers would have expected. And most Corvairs have passed through numerous owners — some who have let them decay badly. A new owner inherits the sins of all of the previous owners, and often discovers them only gradually as the owner learns to maintain and repair the Corvair. Knowledgeable Corvair mechanics are hard to find. Many owners attempt to "wing it", without referring to the shop manual or other quality guides and references. I taught myself how to overhaul my first Corvair engine, and then the Powerglide transmission, at age 16, using only the shop manual to guide me. These valuable references can be downloaded at no cost. They are your "bible" and are essential to the DIY shade tree mechanic. Professional Corvair-knowledgeable mechanics are expensive and rare. CORSA club chapter, if one is near you, can be a big help, as can Internet forums like this one. If you are willing to teach yourself, follow the manuals, and seek guidance and assistance from other Corvair owners you can be successful as you work to decipher the mysteries you inherited when you bought your Corvair.