Squeaking noise after warm up.

68ChevelleSS · #1 06-27-2011, 04:02 PM

I have a loud squeaking, almost like nails on a chalkboard after my 68 is warmed up. It only does it over about 20 mph while driving. I cannot hear it at highway or cruise speed. just annoys the heck out of me. It also does not get louder or quieter with rpm. Seems like you hear it most while slowing down. Not brakes. Also will sometimes do it once warmed up and just sitting idling in park. As soon as I put it in gear it stops. So far I've disconnected the belts thinking it might be a belt driven accessory. Still squeaks. lol. I thought it might be something rubbing once everything warmed up with the headers and exhaust but I still have at least 2 inch clearance all the way around them. I also pulled the speedo cable out and tried it. Still squeaking! I'm starting to think either a cracked flywheel (cracked between bolt holes) or some sort of vacuum leak. It runs perfect even while squeaking. Its very weird and driving me insane. Whats your thoughts and opinions? Very embarassing and annoying to drive such a nice car that squeaks horribly. I've heard flywheels that sound like a knocking noise when cracked but never nothing like this. Any info would be extremely helpful. Just some info on the car: 383 450hp golens crate engine/brand new TCI Street Fighter TH400. Engine has about 3500 miles on it. Trans maybe 500 miles. Thanks.

Hank70SS · #2 06-27-2011, 05:48 PM

Hard to tell from this end of the wire, can't quite hear it.

I would lean towards a vacuum leak but again without being able to hear it's hard to say. Maybe a ruptured diaphragm in the vacuum advance canister? I had that happen but I could only hear at high rpm. Maybe a leak around the carb baseplate. You can use a propane torch to track a vacuum leak. Turn on gas, don't light it, and shoot the gas around the carb base and other areas you suspect. If the engine idle changes you found a leak.

I have a stick so don't know much about the flexplate and trans. You could pull the inspection cover and make sure all the torque converter bolts are tight.

Good luck and let us know what you find.

68ChevelleSS · #3 06-27-2011, 05:58 PM

Thanks for the quick reply. I'm leaning towards a leak too. Just really weird. DOn't understand why it would only do it after warming up and not do it at idle and just revving it up. Drives me crazy! I hope i can figure it out quick! thanks again!

Ms Grumpy · #4 06-27-2011, 10:16 PM

Good Luck. Let us know what it was.

68ChevelleSS · #5 06-27-2011, 10:35 PM

Thanks Ms. Grumpy! Hopefully i still have hair when i figure it out. lol.

68ChevelleSS · #6 06-28-2011, 01:32 PM

Tried the leak idea. No leaks and no change of idle. Still squeaking. Any other ideas before I separate the trans from the engine to check the flywheel for cracks?

Hank70SS · #7 06-28-2011, 05:56 PM

Umh? Alt or water pump bearings? Oh, you said you disconnected the belts. You can check the torque converter bolts without pulling the trans all the way loose. Have you had a rider help to try and isolate the noise while driving?

68ChevelleSS · #8 06-28-2011, 06:09 PM

yes, have had my Brother and wife in the car with me. I've checked the torque converter bolts a few times. Starting to think its a crack in between the 6 holes of the flywheel. I've seen these crack before but they usually make a knocking sound almost like a bottom end knock. this is driving me nuts. I would also think if it was a flywheel crack it would make different noises at different RPMs. Makes the exact same noise at the same volume whether running 5,000 rpm or idling coming to a stop. I drove it down the road today while it was squeaking and shut it off in neutral and the squeak went away. so definitely something drivetrain related.

68ChevelleSS · #9 06-29-2011, 05:20 PM

I'm trying to post a video of my car squeaking so everyone car hear it. How do i do that?

Thanks,
Boyd

Hank70SS · #10 06-29-2011, 05:48 PM

I have no idea, never done it. I'm sure Grumpy or Mrs. Grumpy can help you out.