Annoying intermittent chirping noise from back of SBC. Help!

@Bad Banana Holy crap this post saved me a ton of work. Mine has been doing the same on occasion and it was driving me nuts. Got it to act up today, closed off my pvc and the noise stopped. Before this I would have said BS but it got me. Thanks for posting and your help

 

Hey guys, sorry I took so long. I just got busy with some other stuff and couldn't make any time to get back on the car. Then the app was turned off so I couldn't access the HAMB from my phone. I've been using my phone to get on the HAMB for so long, I forgot my password. When I tried to reset my password, I realized that I had not updated my email address, so I couldn't reset my password!

Now that the app is working again, I'm signed on so here I am. My new task is to get my email address corrected and my password reset.

The good news is that I found the source of the damn noise. I feel like a douche because it was something so obvious. After checking all the suggested items & using a stethoscope, I couldn't find anything wrong. I tried listening with a hose up to my ear and still couldn't pinpoint it.
While lying on my back staring up at the bottom of the motor, I noticed a metal shield barely touching the driver's side exhaust pipe, just as to pipe bends towards the firewall. I pushed up on the shield and the noise went away.

Thanks for all the suggestions. Enjoy the rest of your day after you finish laughing at me!


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Here's a couple of pics. The first is from underneath, after I pushed the shield up. The second is from up above. Pretty obvious huh? I must've had my head up my ass. I was looking for a mechanical problem, not something as simple as something touching the pipe.


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I have had my head up my ass most of my life. We have all been there my freind

 

Just for the record, from my own personal experience, a cracked flexplate creates a knocking sound. It can make the bottom of your stomach fall out from the idea that gets in your head that a rod is knocking. When I had it happen to me, I was on the verge of crying because it was a newly minted car with a freshly rebuilt engine. Only through good fortune and luck did I discover the source of the sound. I wanted to put this on HAMB in case anyone else is confronted with a similar situation, even if as well all know there are exceptions to every damn thing that happens to a machine as complicated as a motor vehicle. I am very glad 55 1st Series was able to suss out the problem and fix it without having to pull an engine or transmission, which we all know is a bitch, and could have been gone through without finding the problem, put back in for him to have it start all over again. 55 1st Series, you are not thick between the ears. I'd say you were methodical and observant. Three cheers for you!!! And, for all who posted, thanks, I learned a few things I didn't know. I'm sure we all did.

 

I just had the same problem on a 56 Caddy v8 recently. My original motor was at the machine shop and is going to take awhile and cost more than expected. So I bought a newer Caddy 390 off Craigslist for $800 so I could drive this thing this summer. Got it in, stuck the new front pipes and mufflers on a cranked it up. Sounded great and ran smooth. Found a couple issues I needed to fix and while I was underneath I stuck the rest of the new exhaust on. Couple days later I come back to it and take it for a trip around the block....everything is good. Park it in the driveway and leave it running while I run in the house to get a cold drink. When I come back it's running rough and it has the guy wrenching metallic scrape/squeak coming from the bottom end. You know that noise a dry spun rod bearing makes? Yeah....that's the one.Now it's running like one cylinder has dropped out and it's down on power. I was so sickened I didn't even touch it for 3 days. Finally I went out and decided to drive it up on some ramps to see how tough it would be to pull the pan. When I tried driving up the ramps it was really struggling....then suddenly the noise stopped. One of my pipes was rubbing the frame where it passes through and the rough running was causing the squeak. The rough running turned out to be a bad set of points. Replaced the pints and it ran smooth with no noise. Talk about a relief.