So everything is just about done on the Camaro and i was going to get it registered soon, but today it seems the engine started knocking. The noise seems to be coming from the oil pan, but i cannot really pin point it. The other strange thing i noticed is that 1/3 of the flex-plate teeth are worn away. Im pretty sure it wasn't like this before as i was looking at the plate when i changed the trans pan gasket last week. I don't know if the engine is knocking, or the noise was somehow related to the worn flexplate teeth. I have a video of the noise below, as well as pictures of the flexplate.

‪1986 camaro knock‬‏ - YouTube

 

That sounds almost like a chatter to me. And the rounded teeth on the flexplate is like the bendix gear is zinging them off. Check your starter to make sure the bendix gear is retracting out of the way of the flexplate. Does the starter make a nasty grinding noise when you start the engine? Also try to rock the flexplate and the torque converter to see if either one is loose.

 

I just checked and the starter is disengaging the flex plate. The plate and converter are also both tight. I made another video. It stops clanking and starts knocking as the rpms go up high enough. Also, it seems to make no noise when in drive or reverse, but i think that's because the rpms drop in gear. Here is the new video:

‪1986 Camaro knocking 2‬‏ - YouTube

 

When it's idling, that doesn't sound like a knock. And the flexplate teeth look so uniform, it's like they're getting "ground" down. Take a look around the whole perimeter of where the flexplate rides, and check for a bolt, or anything that may be sticking out and riding against the teeth. That's what it looks and sounds like to me.

 

What would cause the teeth to only be ground down on one spot? Wouldn't they be like that all the way around if the plate was rubbing against something? Ill take another look at the flexplate tomorrow and check if anything is touching it.

 

Well no, that's different then. I couldn't tell that the teeth weren't worn like that all the way around. Since the teeth are ground in one spot, that's from zinging the starter gear into the flexplate (oops starting the engine when it's already running). Or it could also be from having too loose of a starter to flexplate gear mesh, which is why I asked if your starter makes a bad noise when you start the engine. Either one of these isn't the source of your noise though.

 

Can any work be done to the bottom end with the engine in the car? I had plans of swapping in a 350 or 383 later down the line, but i wanted to be able to drive the car while i saved the money for the new engine.

 

Well, it spun a bearing. Look at the nice glittery oil.



Put magnet in the oil and plenty of fine metallic particles stick to it.

 

It still doesn't sound like a rod knocking, but a recording might not capture the sound as if in real life. That flex plate looked pretty chewed up. Almost as if it were warped.

 

Yea the camera picks up mostly treble so you cant hear it as if your were there. Plus now i can hear it loud from under the hood, it sounds like its coming from the bottom of the engine. Im gonna lift the engine and pull the pan and oil pump. If its not a crank bearing im gonna plastigage the journals and slide in the appropriate sized bearing. I just want to get at least year out of this engine, as im gonna start saving up for a 350 in November. If it turns out to be a crank bearing, or if the journals are really messed up, im gonna pull the engine, do the rings, bearings, crank, and swap on a new flexplate. I can get the parts for relatively cheap so doing the work is the only real cost. Plus when i get the 350 i can sell the 305 as a rebuild. But if i can slide in a bearing without doing the work, id rather try that first.