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Help...Strange rattling noise!

leeboy66

Well-known member
Joined
Dec 27, 2005
Messages
61
Location
Long Island, New York
Corvette
1977 Bright Yellow Coupe
Here's my problem: I have begun to hear a strange rattling noise coming from the vacinity of my engine. It seems to be emitting from the bottom rear of the engine. I'm not exactly sure, but that's what i think. The weird thing is that the noise is not continuous. I usually hear it after the car has warmed up, but it comes and goes as I drive. I don't usually hear it while driving, just at idle when stopped in traffic. Today it just went away as the car idled after about an hour cruise. Yesterday I could hear it loud and clear at the end of a ride. What could it be? My mechanic told me that the timing chain cover had been worn away and that I would need it replaced soon. Could this be the source of the strange rattling sound?
 

bradfordsvettes

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Joined
Mar 28, 2001
Messages
549
Location
Boston, MA area
Corvette
jewel blue 61.cranberry 69 t-top.black rose 92
it could be the chain eating away at the cover you could check it and get some idea how worn it is by watching the dist rotor while turning the crank back and forth the rotor should move with little hesitation back and forth. I have also seen the baffle come loose in the pan and rub on the crank that was a real odd one but it obviosly can happen Steve
 

Artsvette73

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Joined
Jan 24, 2004
Messages
174
Location
New Jersey
Corvette
1973 Silver coupe, 1977 L48
If you still have the stock exhaust manifolds, it maybe the heat riser on the passenger side.
 
V

vette-dude

Guest
Since you said it is coming from the rear of the engine--If it is a manual Trans it could be the throw out bearing. If it is an Automatic it could be the flexplate. If the timing chain is the culprit, it is way too loose and the car should be down on power and possibly running a little rough at an idle. Trying to diagnosis a noise in your engine over the internet is kinda like trying to guess how much you weigh by how long your post is. Try to be more definitive of the noise, tell us more about the car, and maybe we can help you pin point areas to investigate.

Randy:w
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,521
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
Since you said it is coming from the rear of the engine--If it is a manual Trans it could be the throw out bearing. If it is an Automatic it could be the flexplate. If the timing chain is the culprit, it is way too loose and the car should be down on power and possibly running a little rough at an idle. Trying to diagnosis a noise in your engine over the internet is kinda like trying to guess how much you weigh by how long your post is. Try to be more definitive of the noise, tell us more about the car, and maybe we can help you pin point areas to investigate.

Randy:w
My guess is a Crack in the Flex Plate or Torque Converter Bolts and or Bolts to the Crankshaft Loose!! I've seen it allot!! Replaced Lots of GM Flex Plates!! I've also had the starter drive go bad and not fully retract from the Starter ring!!
 
V

vette-dude

Guest
My guess is a Crack in the Flex Plate or Torque Converter Bolts and or Bolts to the Crankshaft Loose!! I've seen it allot!! Replaced Lots of GM Flex Plates!! I've also had the starter drive go bad and not fully retract from the Starter ring!!

Yep, that was my first thought too but only if it is an automatic. Unfortunately, my crystal ball is in the shop being repaired at this time so I had to rely on reading tea leaves to guess at what leeboy66's vette is equipped with. Keep in mind that my crystal ball was formerly owned by the wicked witch of the North and it is getting alot of ghost images of Flying Monkeys, Yellow Brick Roads, and Lions, Tigers, and Bears "Oh My!" for some reason. :W

Randy
 

74bigblock

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Joined
Sep 30, 2003
Messages
1,153
Location
Ingleside, IL
Corvette
2008 Z06 / 2006 BMW 330i Spt Pkg
Yep, that was my first thought too but only if it is an automatic. Unfortunately, my crystal ball is in the shop being repaired at this time so I had to rely on reading tea leaves to guess at what leeboy66's vette is equipped with. Keep in mind that my crystal ball was formerly owned by the wicked witch of the North and it is getting alot of ghost images of Flying Monkeys, Yellow Brick Roads, and Lions, Tigers, and Bears "Oh My!" for some reason. :W

Randy

Randy,

I'm shocked and appauled that you left DUCT TAPE out of your laundry list.

Dave
 

leeboy66

Well-known member
Joined
Dec 27, 2005
Messages
61
Location
Long Island, New York
Corvette
1977 Bright Yellow Coupe
My car is a 1977 L48 4-speed. At first I thought the noise sounded like a miss or a ping, but it comes and goes as I said before. It sounded like something loose in the exhaust system...it is the original 1977 system and is rusted. I only really hear it at idle, after warm-up. It gets pretty loud at times....sounding like, "dink, d...dink dink". Then goes away while cruising. I sometimes hear it a bit while driving in first gear only. I hope these details help a bit. I understand the limitations of trying to diagnose a problem online, but appreciate any of your thoughts.
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,521
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
My car is a 1977 L48 4-speed. At first I thought the noise sounded like a miss or a ping, but it comes and goes as I said before. It sounded like something loose in the exhaust system...it is the original 1977 system and is rusted. I only really hear it at idle, after warm-up. It gets pretty loud at times....sounding like, "dink, d...dink dink". Then goes away while cruising. I sometimes hear it a bit while driving in first gear only. I hope these details help a bit. I understand the limitations of trying to diagnose a problem online, but appreciate any of your thoughts.
May be a Broken spring in the Pressure Plate or Clutch Disk!!:upthumbs
 
V

vette-dude

Guest
Okay, let see. Could be a loose sparkplug. Could be a catalytic convertor coming apart inside. Could be a muffler coming apart inside. Could be an exhaust leak either at the manifold to head or manifold to exhaust pipe. As mentioned before the heat riser. As mentioned before, clutch problems. Might be a pilot brg in flywheel (doubtful unless you are getting clutch chatter). OR maybe you just need to crank up the volume on the stereo! LOL

I would start at the plugs as they do sometimes back out. Might even check the plug wires to see if they are arcing (do this in the dark at night with engine running). Then look over complete exhaust system from heads all the way back. Look for black soot on gskts or pipes. If you find that, start the engine and see if you can feel exhaust porting where you found the soot. One other thing I guess would be a loose rocker arm. This would be a ticking noise especially at idle. Good luck.

Randy
 

leeboy66

Well-known member
Joined
Dec 27, 2005
Messages
61
Location
Long Island, New York
Corvette
1977 Bright Yellow Coupe
Randy, I think your suggestion about the stereo is best...I'll just crank up the volume and drive!!!
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,521
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
I would start at the plugs as they do sometimes back out. Might even check the plug wires to see if they are arcing (do this in the dark at night with engine running).
You can check this in the daylight too!! Just reach down there and grab them,You'll find out if there arcing real Quick!!!:upthumbs The severity can be checked by how much u-rine ran down your leg!!:D
 

Evolution1980

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Administrator
Joined
Feb 25, 2002
Messages
4,292
Location
Cleveland, Ohio
Corvette
ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
You can check this in the daylight too!! Just reach down there and grab them,You'll find out if there arcing real Quick!!! The severity can be checked by how much urine ran down your leg!:D
Good call, Bubba! :L
 

bradfordsvettes

Well-known member
Joined
Mar 28, 2001
Messages
549
Location
Boston, MA area
Corvette
jewel blue 61.cranberry 69 t-top.black rose 92
there are a lot of things it could be . my crystal ball is cloudy also.like said before hard to diagnose over the net . ditto on the flex plates Steve
 
A

aapple

Guest
Could also be the harmonic balancer rubbing on the timing chain cover. If the outer ring "spins" on the inner hub, usually the outer ring will move to the rear, and rub on the cover. It could make a tink-tink sound, a grinding noise, or a rattle. Just another thought...;troll
 

Evolution1980

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Administrator
Joined
Feb 25, 2002
Messages
4,292
Location
Cleveland, Ohio
Corvette
ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
any chance of it having to do with the clutch fan? Maybe worn or something and when it's supposed to engage it makes some funky noises? Just throwing that out there. (Probably not the issue...)
 

leeboy66

Well-known member
Joined
Dec 27, 2005
Messages
61
Location
Long Island, New York
Corvette
1977 Bright Yellow Coupe
No, it's definitely not the clutch fan. Mine is always engaged and spins continuously . I guess it's not supposed to be, but that's another issue.
 

zachh

Well-known member
Joined
Aug 1, 2005
Messages
221
Location
virginia beach, va
Corvette
1979 black 'n' silver L82 1978 Trans Am Y88
You can check this in the daylight too!! Just reach down there and grab them,You'll find out if there arcing real Quick!!!:upthumbs The severity can be checked by how much u-rine ran down your leg!!:D
BEEN THERE, DONE THAT!!!
55,000 volt distributor..... Woke me up pretty quick. You can also check the severity by how burned your fingertips are and how loud ya yelp!;)
 

2VettesMike

Well-known member
Joined
Sep 27, 2006
Messages
131
Location
Blk Mtn, NC
Corvette
1972 Bryar Blue Coupe 1993 40th Coupe
You may want to notice if it's happens more when the clutch pedal is pushed in. When I put the motor back in my 72 it had a strange come and go ticking sound. Turns out the dust shield on the bellhousing didn't have the little clips hooked on the edge of the oil pan. Move the clips noise went away.

Thanks
Mike
 

leeboy66

Well-known member
Joined
Dec 27, 2005
Messages
61
Location
Long Island, New York
Corvette
1977 Bright Yellow Coupe
Thanks for the suggestion, Mike. But the noise does not seem related to the clutch. There is no change when I push the clutch pedal. I hear it with or without the clutch engaged. The noise comes and goes as I drive. I hear it mostly at idle when stopped at lights.
 

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